Brief Summary of Minutes of Annual Meeting

ACCOMPLISHMENTS   These are only a selection of 2021-2022 results.  This large, collaborative group works on OVER 140 different species of arthropod and weed pests.

Objective 1: Import and Establish Effective Natural Enemies

Objective 1a.  Survey indigenous natural enemies.

A significant discovery this year was the accidental introduction of Orasema minutissima to the island of Hawai'i. As a potential biological control agent against Wasmannia, this is an important find. It was found in the early stages of spread, which allows for the documentation of its spread and impact on the ant. A survey in spring 2022 showed that the wasp has spread around the entire island of Hawai'i, but does not yet occur on the island of Oahu or Maui (and likely not on any of the other Hawaiian islands).  A large revison of the eulophid genus Zagrammosoma, was published - which are parasitoids of lepidopterous leafminers, including a significant number of pest species.

A year-long survey of arthropods with pitfall traps was completed along a gradient of natural to vineyard land in Napa, CA.

Arthropods have been identified, and data analyses are underway. Studies continued on the current distribution, abundance and parasitism of the light brown apple moth (Epiphyas postvittana, LBAM) in California. Larval populations were found in landscape plantings from Santa Rosa in the north to Rancho Santa Fe in the south, but frequency of occurrence and abundance varied considerably between regions and locations. No larvae were found in landscape plantings that had been recently pruned. Larval and pupal parasitism levels were slightly lower than in previous years, but continued to be dominated by Meteorus ictericus, Nemorilla pyste and Pediobius ni.

Attack rates by resident parasitoids and predators on sentinel eggs of bagrada bug, Bagrada hilaris, were assessed by the USDA-ARS in Albany, CA at a total of 51 sites in north-central California. Predation rates were relatively high, exceeding 20% per day on some sample dates, but parasitism rates were very low. Of the 25,387 eggs deployed that were not predated or missing (out of the 35,673 total eggs that were deployed), only 47 (0.19%) were parasitized. Gryon aetherium, a biological control agent for bagrada bug that is currently undergoing testing, was found at one site. Sampling in 2020 and 2021 showed that G. aetherium is widespread in north-central California.

Surveys were conducted for native and the self-introduced parasitoid, Trissolcus japonicus, attacking the eggs of the brown marmorated stink bugs (BMSB), Halyomorpha halys (Hemiptera: Pentatomidae). This project is in its second year. Surveys are concentrating efforts in the Los Angeles Basin, southern California. Survey methods included the deployment of frozen sentinel BMSB egg masses and subsequent collection of these eggs after a 3-4 day exposure period. Field exposed eggs are sent to CDFA for rearing of parasitoids. The goal is to collect the self-introduced BMSB egg parasitoid, Trissolcus japonicus, which has been previously collected in the LA Basin by the Hoddle lab. CDFA will use these parasitoids to start T. japonicus colonies for mass production and release.

Proactive screening of an egg parasitoid, Anastatus orientalis, a natural enemy of the invasive spotted lantern fly, Lycorma delicatula, (Hemiptera: Fulgoridae), is underway in quarantine at UC Riverside. The goal of this project is to have host range and host specificity tests completed for A. orientalis in advance of the anticipated invasion by L. delicatula into California.

Significant progress has been made in host range testing and molecular and morphological identification of native non-target fulgorid species. This is a collaborative project with colleagues on the east coast of the USA where SLF has already established and is spreading. This pest presents a significant threat to California’s grape and nut industries.

Isolates of Oryctes rhinoceros nudivirus (OrNV) are being evaluated as candidates for effective biocontrol of coconut rhinoceros beetle biotype G (CRB-G).

Parasitism by resident parasitoids on spotted wing drosophila (Drosophila suzukii) was monitored in cane berry fields and adjacent semi-natural habitats in the central coast of California.

A novel strain of the egg parasitoid Anagrus daanei (Mymaridae), a natural enemy of the Virginia creeper leafhopper (Cicadellidae: Erythroneura ziczac) has been identified in California.

Investigations continued on the current distribution, abundance and parasitism of the light brown apple moth (Epiphyas postvittana, LBAM) in California. Larval populations were found in landscape plantings from Santa Rosa in the north to Rancho Santa Fe in the south, but frequency of occurrence and abundance varied considerably between regions and locations. No larvae were found in landscape plantings that had been recently pruned. Larval and pupal parasitism levels were slightly lower than in previous years, but continued to be dominated by Meteorus ictericus, Nemorilla pysteand Pediobius ni.

Also in progress is a large revison of the eulophid genus Zagrammosoma, which are parasitoids of lepidopterous leafminers, including a significant number of pest species. The first phylogenomic analysis of relationships in the family Eulophidae was published, which allows us to better predict evolutionary events and host relationships.

Objective 1b.  Conduct foreign exploration and ecological studies in native range of pest.

Several institutions in the western US normally conduct foreign exploration and importation of natural enemies for both new and established arthropod and weed pests this past year.  Many of these exploratory trips are only partially successful.  Species sent to quarantine facilities must survive the trip and reproduce.  Subsequent cultures will then be used for non-target host testing and evaluation for potential release.  Select studies that reported under this objective are summarized below. International travel restrictions due to the Covid-19 pandemic are cited explaining lack of work progress.  Many of these travel restrictions are lifting in 2022.  This objective is dependent on international travel. 

The USDA-ARS in Albany, CA conducted explorations in Argentina and Paraguay for natural enemies of water-primrose, Ludwigia, and conducted host-range testing in quarantine in California, focused on the closest native relatives in the same genus and related genera, which led to rejection of several candidates.

An improved invasive species distribution model was developed for the light brown apple moth (Epiphyas postvittana, LBAM) and we found a positive linear relationship between model predictions of environmental suitability and observed relative abundance of LBAM larvae for localities in coastal California.

Research continues on the parasites of the imported fire ant (Solenopsis) in South America and of the Little Red Fire Ant (Wasmannia) in the Caribbean and Central America. We are working with an Argentinian researcher on the molecular and morphological recognition of ants attacking the Solenopsis saevissima complex, which includes the fire ant. Other papers on parasitoids of ants included a phylogenetic analysis of the genus Kapala, which attack some of the larger ants in the subfamilies Ectatomminae and Ponerinae. We are continuing on new research program on the genus Encarsia, which are aphelinid parasitoids of armored scales and whiteflies. The initial objectives are a revision of the Encarsia strenua species group and a molecular phyogeny of the entire genus.

Research is underway on developing a molecular phylogeny for the egg-parasitic Research is utilizing three different molecular approaches to look at congruence of results, and ultimately the proposal of a new classification for the group. Dominguez did the molecular work for a paper on the genus Macrocamptoptera (Triapitsyn et al. 2020).

We are continuing our work on a National Science Foundation grant to revise the classification of the entire superfamily Chalcidoidea. This is a massive undertaking that involves molecular, morphological and bioinformatic approaches to resolve the relationships of the superfamily, and to disseminate information on the group through electronic resources and a new book that outlines the classification and biology of the group. Members of this superfamily are among the most important natural and introduced control agents of other pest insects, and this will form a foundation for all future studies on the group. Our first publication from this is an analysis of the transcriptomes across Chalcidoidea (Zhang et al. 2020). We have also obtained nexgen sequencing data for over 600 taxa that cover the breadth of the entire superfamily. The final results are in progress and we are working on an edited book to cover the entire superfamily. On this grant we trained two postdocs and four graduate students. We are also taking a bioinformatic approach by developing a new database to house all of the taxonomic and biological information on the superfamily in TaxonWorks, which is based on a migration of data from the Universal Chalcidoidea database. This will manage data for more than 30,000 taxonomic names and over 50,000 literature references, including information on their hosts and distributions.

As well, more than 1000 specimens of Aphelinidae and other Chalcidoidea were curated and added to the Entomology Research Museum collection of parasitic Hymenoptera.

Two parasitoids of Asian citrus psyllid, Diaphorina citri, imported from Punjab Pakistan. One species, Tamarixia radiata, established readily, spread rapidly, and since the inception of this classical biological control program, ACP densities have declined by > 70%. The second species, Diaphorencyrtus aligarhensis, did not establish.

In collaboration with colleagues in Colombia and Brazil, a tentative investigation assessing the feasibility of classical biocontrol of South American palm weevil, R. palmarum, with a parasitic tachinid fly, Billaea rhynchophorae, has been initiated. The goal of this work is to determine whether or not it is possible to mass rear this fly and to ascertain if live flies can be exported out of Brazil to California for safety evaluations in quarantine. Foreign exploration was supposed to have started in summer 2020. It was postponed by 1 year due to high COVID-19 spread in Brazil.

Field surveys for egg, larval, and pupal parasitoids of the avocado pest, H. lauri, in and around Ixtapan de la Sal and Coatepec-Harinas, Mexico in summer 2020 were not initiated due to COVID-19 work restrictions.

Surveys in Africa for candidate biological control agents of Guineagrass are in progress.  Two Eriophyoid mite species, Diptacus sp. and Abacarus sp. have been collected and shipped to stateside quarantine facilities for evaluation. 

Intensive field surveys for classical biological control agents of the southern cattle fever tick, Rhipicephalus microplusare underway in Vietnam.  An unknown microhymenopteran was reared from cattle fever ticks collected in Vietnam.

Surveys were conducted at 30 sites (15 in Montana; 15 in Colorado) of Lepdium draba (hoary cress) for insect herbivores (both native and previously established introduced species) in preparation for evaluating the effects of releasing the recently approved mite biocontrol agent Aceria drabae. 

Objective 1c.  Determine systematics and biogeography of pests and natural enemies.

Molecular and morphological studies of native Fulgoridae have been undertaken as part of the proactive biological control project targeting spotted lantern fly. The 28S, ITS2 and CO1 regions have been sequenced. The 28S sequences need a second round of amplification with different primers to properly identify the three putative native lanternflies species currently designated as A, B, and C.  Preliminary analyses have confirmed three important results: the three morphospecies, A, B and C that have been characterized based on morphology, are genetically different and represent three different species.  Poblicia fuliginosa from the eastern USA is genetically different from specimens collected from the western USA which are also currently recognized as P. fuliginosa.  And finally, the three native lanternfly nymphs collected from fogging surveys of juniper at the South Western Research Station of the Natural History Museum in summer 2019 do not belong to one of the three morphospecies (A, B or C) that have been characterized molecularly.

Eriophyoid species collected from Guineagrass in Africa are being described.

The following projects between our US and International W-4185 cooperating members all feature species that have been the subject of molecular and genetic work this year;  a population comparison of a stem-feeding shoot fly (Cryptonevra nigritarsis) infesting Arundo donax in the south of France;  genetic fingerprinting  of a common garden experiment conducted in Greece to test the host plant specificity of the prospective biological control agent Larinus filiformis for Centaurea solstitialis; preliminary genetic comparisons between populations of the allium leaf miner (Phytomyza gymnostoma) in France and in the USA; genetic monitoring in choice and no-choice testing to ascertain the specificity of Psyttalia ponerophaga, a potential biocontrol agent of the olive fruit fly; phylogenetic analysis, species delineation and taxonomic revision of  egg parasitoids of Bagrada hilaris; a study that resolved the taxonomic status of Aprostocetus celtidis and A. suevius, two Pyrrhalta viburni parasitoids; a genetic fingerprinting of Trissolcus japonicuson Halyomorpha halys from USA and Europe; and a genetic and morphological comparison of parasitoid assemblages of Pyrrhalta viburni and the closely related beetle Xanthogaleruca luteola

All five species of the plumeless thistle genus Carduus are exotic invasives and listed as state noxious weeds in the USA. Multiple populations of an unknown plumeless thistle species were found in remote areas of the deepest river gorge in North America, Hells Canyon National Recreation Area in Oregon and Idaho. The plants were unrecognizable, so ARS Researchers in Sidney, Montana analyzed the plant’s DNA and matched it to specimens from the eastern Mediterranean. Then ARS, working with botanists from Oregon, California and Spain, definitively identified the plants as Carduus cinereus, a species never before found in the Americas. Northwestern states are now taking EDRR (Early Detection, Rapid Response) action on this new invasive threat.

A graduate student is studying the taxonomy and relationships of the tribe Cirrospilini (Eulophidae), which include important parasitoids of the Citrus leafminer and the Citrus Peelminer. This resulted in an upcoming monograph of the genus Zagrammosoma, a group of 24 species that all attack leafmining Lepidoptera. His studies were focused on addressing the evolution of host breadth in the genus. In a final paper relationships are being addressed for species across the entire tribe and a revision to the genera to provide a better taxonomic framework for understanding the underlying pattern of host association and distribution is being developed.

A new research program continues on the genus Encarsia, which are aphelinid parasitoids of armored scales and whiteflies. The initial objectives are a revision of the Encarsia strenua species group and a molecular phylogeny of the entire genus.

Research is underway on developing a molecular phylogeny for the egg-parasitic Mymaridae. This project is utilizing three different molecular approaches to look at congruence of results, and ultimately the proposal of a new classification for the group.

Work continues on a National Science Foundation grant to revise the classification of the entire superfamily Chalcidoidea. This is a massive undertaking that involves molecular, morphological and bioinformatic approaches to resolve the relationships of the superfamily, and to disseminate information on the group through electronic resources and a new book that outlines the classification and biology of the group. Members of this superfamily are among the most important natural and introduced control agents of other pest insects, and this will form a foundation for all future studies on the group. The first publication from this is an analysis of the transcriptomes across Chalcidoidea. Investigators have also obtained nexgen sequencing data for over 600 taxa that cover the breadth of the entire superfamily. The final results are in progress and work continues on an edited book to cover the entire superfamily. This research is taking a bioinformatic approach by developing a new database to house all of the taxonomic and biological information on the superfamily in TaxonWorks, which is based on a migration of data from the Universal Chalcidoidea database. This will manage data for more than 30,000 taxonomic names and over 50,000 literature references, including information on their hosts and distributions.

Besides the large molecular and genetically based revision work, members of this group regularly provide identifications of parasitoids that are directly related to biological projects worldwide.  The benefit of this work to biological control overall is enormous.

Objective 1d.  Determine environmental safety of exotic candidates prior to release.

Oporopsamma wertheimsteini was received from the BBCA and the Russian Academy of Sciences in October 2021, Seventy three adults emerged from feeding tubes (rush skeletonweed project).  Adults were placed in oviposition tubes and a thousand plus eggs were harvested.  Larvae are currently being used for impact studies on non-target plants.

Investigations of the host-specificity of the leaf- and stem-ming moth Digitivalva delaireae (Lepidoptera: Glyphipterigidae) a candidate biological control agent against Cape-ivy (Delairea odorata) by the USDA-ARS, Invasive Species and Pollinator Health Research Unit in Albany, CA revealed that neonate larvae can damage three California native members of the genus Senecio, the closest native relatives in North America in no-choice tests. However, under dual-choice and larval transfer tests, there is either little or no damage (Senecio hydrophillus) or damage with little or no pupation or adult emergence (S. aronicoides and S. triangularis). The risk to non-target plants is thus low. 

The USDA-ARS in Albany, CA evaluated host plant specificity of the eriophyid mite, Aceria salsolae, a prospective biological control agent of Russian thistle (Salsola tragus), in a field garden experiment in Italy.  An addendum to a prior petition was submitted to USDA-APHIS requesting permission to release the mite.

Host specificity tests of the egg parasitoids Gryon aetherium and Trissolcus hyalinipennis, candidate biological control agents for bagrada bug, Bagrada hilaris conducted by the USDA-ARS showed that G. aetherium was capable of developing on eggs of 10 out of the 14 tested non-target species, although emergence rates were <1% for three of these species and exceeded 20% for only three species. In contrast, T. hyalinipennis emerged from 7 out of 11 non-target species and emergence rates exceeded 40% in all cases.

Two host range and safety testing projects were completed for two natural enemy species, Tamarixia radiata and Diaphorencyrtus aligarhensis, imported into quarantine for classical biocontrol of Asian citrus psyllid.

A thrips from South America, Liothrips ludwigi, was tested as a candidate agent for control of three water primrose species (Ludwigia spp.) that are non-native and invasive in the western US. This thrips was able to feed, survive and reproduce on three native congeners in lab tests, precluding further consideration for biocontrol.

Two exotic parasitoids have been tested for host specificity of the bagrada bug; thus far, the parasitoids have been tested on 10 non-target stinkbug species.

A study was conducted on the microbiome of the psyllid, Arytinnis hakani, a biocontrol agent under evaluation against the French broom Genista monspessulana, and Arytainilla spartiophila attacking the Scotch broom Cytisus scoparius. Additional host specificity trials were conducted for Aprostocetus celtidis for biological control of Pyrrhalta viburni; host specificity and investigation of foraging behavior of Psyttalia ponerophaga for biological control of Bactrocera oleae; and host specificity tests in open door experiments for Chrysochus asclepiadeus on Vincetoxicum species and milkweed.

Phymastichus coffea LaSalle (Hymenoptera: Eulophidae) is an adult endoparasitoid of the coffee berry borer (CBB),Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae), which has been introduced in many coffee producing countries as a biological control agent. To determine the effectiveness of P. coffea against H. hampei and environmental safety for release in Hawaii, we investigated the host selection and parasitism response of adult females to 43 different species of Coleoptera, including 23 Scolytinae (six Hypothenemus species and 17 others), and four additional Curculionidae. Nontarget testing included Hawaiian endemic, exotic, and beneficial coleopteran species. Using a no-choice laboratory bioassay, we demonstrated that P. coffea was only able to parasitize the target host H. hampei and four other adventive species of Hypothenemus: H. obscurus, H. seriatus, H. birmanus and H. crudiae. H. hampei had the highest parasitism rate and shortest development time of the five parasitized Hypothenemus spp. Parasitism and parasitoid emergence decreased with decreasing phylogenetic relatedness of the Hypothenemus spp. to H. hampei, and the most distantly related species, H. eruditus, was not parasitized. These results suggest that the likelihood of non-target impacts is low because there are no endemic species of Hypothenemus in Hawaii, and P. coffea could be safely introduced for classical biological control of H. hampei in Hawaii.

Objective 1e.  Release, establish and redistribute natural enemies.

Many releases and redistributions of natural enemies (millions) were carried out against pests in 2021.

Russian knapweed:  Approximately 3,750 adult Aulacidea acroptilonica were reared from galls collected from Broadwater County, MT April 2021. However, poor emergence of wasps occurred from galls.  Gall wasps were consigned to cooperators located in Carbon, Petroleum, and Teton counties, as well as the Rocky Boy’s Reservation.

Invasive hawkweeds:  Female Cheliosia urbana were collected in collaboration with CABI Switzerland between 27 April and 9 May, 2021. Approximately 200 eggs and 9 females were sent to Montana on 18 May. Due to a delay during the transport females died without laying new eggs. The few larvae that hatched during shipment died before arrival and no larvae hatched from the remaining eggs.

Hoarycress: Researchers at Montana State University are currently rearing two populations of the gall mite, Aceriadrabae. The original rearing colony has been maintained since 2016.  These mites were collected in Bulgaria by the BBCA at a higher elevation site and was supplemented in 2018. In 2021 a collection as made by the (BBCA) from north-central Greece.  Galls were received at the MSU containment facility in late May, 2021. Approximately 3,176 mites were individually transferred to plants to initiate a new colony. Four releases of the mite have been made in Montana. Two initial releases were made in 2019 in Gallatin (Bozeman) and Broadwater (Toston) counties. Due to the size of the infestation at Toston, we made additional releases at this site in 2020.  In 2021, two more release sites were added: Lake (Charlo) and Lewis & Clark (Helena) counties

Biological Control of swallow-worts: In 2021 over 1100 adult Hypena opulenta moths were released at 28 field sites in lower Michigan. The 18 field sites from the 2020 releases were monitored. The releases aim to test the importance of genetic diversity and release size for establishment success.

Brown marmorated stink bug biological control. Adventive populations of the parasitoid Trissolcus japonicus were reared in the laboratory at Michigan State University. 20,000 adult parasitoids were released at 10 field sites in 2021. The releases aim to test how habitat type (monoculture vs. polyculture) influences establishment success.

Knotweed biological control: The Kyushu host race of Aphala itadori was released at 10, and the Hokkaido host race at 2 field sites in Michigan. A total of 2360 psyllids were released in summer 2021. The releases test how release frequency may impact establishment success

The shoot tip-galling fly Parafreutreta regalis (Diptera: Tephritidae), the world’s first biological control agent against Cape-ivy (Delairea odorata), was released by the USDA-ARS and cooperators in southern California at 18 sites in California. By the end of 2021, establishment was confirmed at six sites.

The leaf-feeding planthopper Megamelus scutellaris, a biological control agent of floating water hyacinth (Eichhornia crassipes or Pontederia crassipes) was released by the USDA-ARS with cooperation from the Division of Boating and Waterways, California Department of Parks and Recreation, at 18 sites in the Sacramento-San Joaquin Delta of northern California between 2018 and 2020. By the end of 2021, evidence of limited, low-density establishment was obtained at three sites.

The root- and rosette-feeding weevil, Ceratapion basicorne, characterized by the USDA-ARS in Albany, CA, was approved for release in 2019. It is the first agent targeting this weed that feeds on the taproot and leaves of immature plants.  It has been released by the USDA-ARS at three sites in California, but establishment is not yet certain.

The alligatorweed flea beetle Agasicles hygrophila, collected from established and impactful populations in the southeastern U.S. was released by the USDA-ARS, Albany, CA at several sites in the southern Central Valley of California. Establishment is uncertain.

The Coconut Rhinoceros  (CRB) invading Guam (2007), Hawaii (2013), Papua New Guinea (2015), and Solomon Islands (2015) are genetically different from other populations off this pest, are resistant to Oryctes nudivirus, the biocontrol agent of choice for this species, and behave differently. For these reasons, they are being referred to as the "the Guam Biotype" CRB-G.   Earlier this year positive PCR tests resulted for OrNV in field-collected CRB-G. However, a tightly controlled follow-up survey did not detect OrNV in the Guam CRB-G population. It was concluded that the positive tests were a result of lab contamination.

A Guam scientist was to hand carry the parasitoid Tamarixia radiata from the CDFA insectary at UC-Riverside for release against Asian citrus psyllid, Diaphorini citri, on Guam.  This has been put on indefinite hold due to travel and quarantine restrictions resulting from the Covid-19  pandemic. 

Introductions of A. daanei were made into the California North Coast region from 2015-2017 for control of the Virginia creeper leafhopper, which led to some increase in biological control, but populations have not established.

The first release of the root and rosette-feeding weevil Ceratapion basicorne for biological control of yellow starthistle (Centaurea solstitialis) in California was made on 9 April, 2020.

The arundo shoot-tip galling wasp Tetramesa romana, released for biological control of arundo (Arundo donax), has established populations at two sites in the Central Valley of northern California.

Plans were made to continue monitoring all release sites of Aphthona spp. and Oberea erythrocephala against leafy spurge in New Mexico in 2021.  Investigators were unable to visit any sites in 2020 due to travel restrictions. 

Mecinus janthiniformis for biocontrol of Dalmatian and yellow toadfax are established at the southern release site in Grant County.   Releases were made of beetles at two new sites in Grant County near Silver City, NM.  Visits to the northern insectary of M. janthiniformis or any of the Mecinus janthinus release sites did not occur in 2020 due to travel restrictions.

Visits were curtailed to the northern insectary sites of J. ivannikovi in San Juan in 2020 due to travel restrictions.  The small insectary in Chavez County (near Roswell) is still producing small numbers of early summer galls. 

Aulacidea acroptilonica continues to increase exponentially at two release sites. At the original site in Rio Arriba County near El Rito, populations exceed 50/square meter over a 5 ha area.  It seems a new site is established in Otero County near La Luz, NM.  Hundreds of galls can be found near the original release locations.  Plans are to collect from both of these sites in the spring of 2021 for redistribution throughout New Mexico.

Objective 1f.  Evaluate natural enemy efficacy and study ecological/physiological basis for interactions.

The Russian knapweed gall midge is a relatively new biological control agent for the invasive plant, Rhaponticum repens (Russian knapweed). In Wyoming, the midge has not established well at most release sites, and where it has established, the midge creates galls on a small percentage of knapweed shoots (<10%). A hypothesis for the poor performance of the midge in Wyoming is that a lack of late summer rainfall causes a bottleneck for midge populations. Results of population surveys at an established site in central Wyoming were analyzed to evaluate this and other hypotheses. Contrary to expectations, gall midge abundance was not related to precipitation during any of the summer months. Instead, the number of galls during the summer was positively correlated with precipitation during the preceding October-May. Results suggest that gall-midge releases should be made in summers preceded by wet winters, and that successful establishment may be greater at sites that receive relatively high precipitation during October-May.

Rush skeletonweed: The root boring moth Bradyrrhoa gilveolella has been found to be established at one location in southern Idaho. Monitoring of moth populations and possible impact on plant density and plant size continued. Plant density has declined from 29.1 plants/ 0.25 m² to 0.5 plants in 2021.

The shoot tip-galling weevil Lepidapion argentatum (Coleoptera: Cuculionidae) was evaluated in quarantine laboratory studies by the USDA-ARS to determine its impact on young (6-week old) seedlings of French broom (Genista monspessulana). Galling by females confined on shoots reduced shoot growth by 55%.

The stem weevil, Mecinus janthiniformis, released in 2008 and again in 2014 in southern California at Hungry Valley State Vehicle Recreational Area, reduced abundance of Dalmatian toadflax (Linaria dalmatica) by 99% within 5 years in annual surveys conducted by the USDA-ARS from Albany, CA.

Tests were conducted by the USDA-ARS in Albany, CA to determine whether the parasitoids Gryon aetherium and Trissolcus hyalinipennis, candidate biological control agents for bagrada bug, Bagrada hilaris, are able to locate and attack bagrada bug eggs in the soil, where the bug lays most of its eggs. Overall, more eggs were attacked by G. aetherium compared to T. hyalinipennis, indicating that G. aetherium is a more efficient parasitoid of bagrada bug eggs. Furthermore, G. aetherium was able to parasitize about 24% of naturally buried eggs, while T. hyalinipennis parasitized 0%. Subsequent tests showed that G. aetherium can more efficiently search in soil with higher clay content and larger particle size.

The effectiveness of a commercially available predatory mite, Stratiolaelaps scimitus, was tested as a biological control tool. This first involved identification of the species of bulb mites that are associated with saffron corms, and learning how to rear them in the laboratory. Lab trials were also conducted to determine what release rate was best to suppress pest problems. Through this research, it was determined that the predatory mite species tested consumed the bulb mites quickly, and the 1:5 predator/prey ration was the most effective. Results showed that combining predatory mites and an insect-killing fungus increased the effectiveness of bulb mite suppression.

From vineyard pitfall trap samples, spider gut contents were sequenced to determine their diets, and the extent to which they contribute to biological control of vine pests.

Comprehensive field evaluations of the impacts of Tamarixia radiata and native natural enemies on the invasive citrus pest, Asian citrus psyllid, were completed. Studies conducted across numerous sites and 2-3 years conclusively demonstrated that target pest densities declined by >70% since the inception of the classical biocontrol program targeting this pest.

Aulacidea acroptilonica and Jaapiella ivannikovi release sites continued to be monitored in Montana for changes inRussian knapweed density and cover. At some sites the density of Russian knapweed has declined, and plantsappeared stunted, but it is uncertain if that is due to the presence of biocontrol agents, environmental factors; or acombination of both.

Research was conducted to understand the importance of non-consumptive effects of biological control agents on their hosts/prey.  The Investigators completed a synthetic review of this topic, and are working on laboratory experimentation to examine how pea aphids, Acyrthosiphon pisum, respond to cues of predation and parasitism risk.

Field studies of the entomopathogenic nematode, Steinernema riobrave, have been conducted and this indigenous natural enemy has proven to be effective against cattle fever ticks.  Recently studies have shown that the nematode can remain viable in water droplets on vegetation for up to 3 hours.  This allows for the nematode to be passively transferred to tick infested wildlife.

Parasitism rates of Pyrrhalta viburni by Aprostocetus celtidis in the field were evaluated.

Chrysochus asclepiadeus exposed in open field tests to non-target plants and milkweeds, showed no herbivory impact.

Gryon gonikopalense was tested on Bagrada hilaris and several closely related pentatomids.

Studies have now determined that the southward spread of Tamarix leaf beetle (Diorhabda carinulata) is unlikely to be due to the evolution of increased flight tendencies at the range edge. Common environment experiments show that individual female beetles from edge populations are larger, and have a tendencies towards higher fecundity than individuals from the core of the range, suggesting those populations are evolving in response to high host abundance and weak competition. There is substantial heritable variation for the evolution of cues leading to winter diapause. Populations in the south have evolved to initiate diapause at a shorter day length than northern (core) populations.  Host choice evaluation of beetles from populations where hybrids are common between the Diorhabda species indicate they prefer tamarisk.

Host-seeking behavioral assays of the gastropod-parasitic nematode Phasmarhabditis hermaphrodita were performedagainst several different species of slugs.  Other studies included; evaluation of the virulence of different species of Phasmarhabditis against the invasive white garden snail, Theba pisana; host-seeking behavioral assays of entomopathogenic nematodes, evaluating the effects of storage time on host-seeking behavior; as well as evaluating the potential of a new nematode, Tarantobelus jeffdanielsi, in the biological control of insects. This nematode was found in association with tarantulas.

Objective 2: Conserve Natural Enemies to Increase Biological Control of Target Pests.

Objective 2a.  Characterize and identify pest and natural enemy communities and their interactions.

Research on the citrus peelminer (Marmara gulosa) and citrus leafminer (Phyllocnistis citrella) has involved collaborations for the identification of parasitoids from field studies in California and central Mexico.

Studies will be addressing relationships in the Gonatocerus species group, which include important egg parasitoids of sharpshooters in California. This will be the first molecular analysis of the group and will try to address some recent controversial taxonomic changes that have been made at the genus level.

The efficacy of floral resources for enhancing native natural enemies, predatory syrphid flies, was evaluated. Results indicated that access to floral resources that provide adult hover flies nectar and pollen in citrus orchards, were associated with increased natural enemy activity and subsequent predation of the target pest, Asian citrus psyllid nymphs, increased and pest densities declined significantly when compared to control plots lacking floral resources.

Assessments were made on the occurrence and abundance of indigenous early egg parasitoids, Trissolcus japonicus on Halyomorpha halys in the U.S.

The presence of Aculops moisonensis as a foliage herbivore was noted on Ailanthus altissima in France and Greece

Comparisons of parasitoid assemblages of Pyrrhalta viburni and Xanthogaleruca luteola were performed.

Investigations were made of the assemblage of parasitoids associated with Scolytinae in Hawaii as potential conservation biocontrol agents.  Numerous species were identified attacking various Scolytinae (but not coffee berry borer), including Euwallacea sp., and one of the putative vectors of the Ohia Rapid Death causative pathogen.

Research on the citrus peelminer (Marmara gulosa) and citrus leafminer (Phyllocnistis citrella) has involved assistance with the identification of parasitoids from field studies in California and central Mexico. Work continues researching the eulophid parasitoids associated with Citrus Leafminers

Work will be addressing relationships in the Gonatocerus species group, which include important egg parasitoids of sharpshooters in California. This will be the first molecular analysis of the group and will try to address some recent controversial taxonomic changes that have been made at the genus level.

Objective 2b.  Identify and assess factors potentially disruptive to biological control.

Field studies show that a new Bt cotton targeting plant bugs and thrips has minimal non-target impacts on natural enemy communities and their biological control function. A high quality meta-analysis showed that genetically modified Bt maize has little impact on non-target arthropod including natural enemy species and their biological control function. 

Field studies demonstrated that a plot size of 12 x 12 m is sufficient to optimally measure non-target effects of insecticides and GM crops.

Invasive Argentine ants protect Asian citrus psyllid nymphs from natural enemies. This protective mutualism is detrimental to natural enemies and when ants are present natural enemy impacts decline significantly. Current efforts are focused on automated in-field monitoring of foraging Argentine ants. Ants use smooth PVC irrigation pipes as superhighways to move over the orchard floor from subterranean nests to tree trunks where they tend colonies of sap sucking pests, including ACP. Ants harvest honeydew and return it to the nest. In return for food ants protect pests from natural enemies. The goal of this work is to use infrared sensors attached to irrigation pipes and the internet of things to monitor ant activity in near real time to identify hot spots within orchards that require ant control. Additionally, investigations will probe the efficacy of cover crops for increasing natural enemy activity against sap sucking citrus pests, and whether or not conservation biocontrol is synergized when ants are controlled. To control ants a novel control method is being developed, biodegradable hydrogel beads to deliver ultra-low concentrations of insecticide in 25 percent sucrose solution. Ants drink this poisoned sugar water, return it to the nest where they share it with other workers and queens. This transferal process intoxicates nests and kills them. This work, planned for summer 2020, was significantly curtailed due to COVID-19 work restrictions.

Scientists in Guam continued to survey invasive ants on the islands of Saipan, Tinian, and Rota in the Mariana Islands through March 2020 at which time travel to the CNMI and elsewhere was prohibited due to Covid-19 quarantine restrictions.  However, ant surveys continued on Guam throughout the year.  This activity is part of an ongoing USDA-APHIS-CAPS funded project on the surveillance of Wasmannia auropunctata and Solenopsis invicta on Guam and the CNMI.  A related study seeks to describe attendance behavior of Guam’s invasive ants towards aphids, scales and mealybugs commonly encountered in the Marianas, and the effects this might have on biological control agents against hemipteran plant pests. 

Research into the effects of Wolbachia on parasites continues.  Populations of Bagrada hilaris and the two parasitoidsGryon gonikopalense and Trissolcus hyalinipennis were tested for the presence of the reproductive manipulator Wolbachia.

Drought continues to be an important limiting factor for the successful expansion of the gall midge, Jaapiella ivannikovi, on Russian knapweed.  Studies followed populations of gall midges through an extended drought from 2018 through 2021.

Work continued to understand the impact of RNA viruses on the efficacy of the predatory biocontrol agent Geocoris pallens.  This includes work on virus discovery, assessment of which viruses are virulent (causing decreased body condition or fecundity), and assessment of which viruses might be candidates for causing elevated expression of cannibalism by G. pallens.  This project is also conducting modeling studies to determine the impact of a cannibalism-amplifying pathogen on the population dynamics of G. pallens.

A team at the University of Wyoming focused efforts on understanding factors that limit biological control of alfalfa weevil Hypera postica. The most common parasitoid of alfalfa weevil in Wyoming is the wasp Bathyplectes curculionis, at levels as high as 50 percent of alfalfa weevils assays. However, alfalfa weevil remains quite problematic, so in 2019 the focus was shifted to evaluate which hyperparasitoids are infecting this wasp, to learn if this is disruptive to biological control in this system. Thus far, 4 different species of hyperparasitoids were found, and investigators are still working on identifying these species. Fieldwork continued in 2020, with a new methods study focused on establishing best practices for rearing parasitoids and hyperparasitoids out of B. curculionis cocoons. This methods study remains in progress and results will be summarized in next year’s report. 

Objective 2c.  Implement and evaluate habitat modification, horticultural practices, and pest suppression tactics to conserve natural enemy activity.

From 2017-2020 spotted wing drosophila, Drosophila suzukii, and its natural enemies were sampled in cane berry fields and neighboring semi-natural habitat containing uncultivated blackberry (Rubus spp.), a widespread host of D. suzukii. Although D. suzukii was more abundant in and near semi-natural habitat than in berry fields, the parasitoids attacking it, Trichopria drosophilae and Pachycrepoideus vindemiae, were not affected by landscape context.

Planting of cover crops such as alyssum, increases natural enemy activity, especially hover flies, and densities of target pests, such as Asian citrus psyllid decline as a result.

Since 2018, studies have been evaluating the use of summer trap crops in California pistachio orchards to attract plant bugs, Leptoglossus zonatus, away from the crop canopy while young nuts are more vulnerable to bug damage.  In parallel, studies have been assessing the impact of these trap crops on supporting and improving biological control activity of the key L. zonatus egg parasitoid Gryon pennsylvanicum (Scelionidae).

Conservation biocontrol field evaluations assessing the efficacy of flowering plants (e.g., alyssum) for natural enemies (both parasitoids and generalist predators [especially hover flies]) attacking sap sucking pests, including Asian citrus psyllid, infesting citrus was supposed to have started in summer 2020. These field studies didn’t start because of COVID-19 work restrictions. Experiments were conducted using marigolds and alyssum in association with saffron plantings to determine their attractiveness to natural enemies. The plants survived well in the plants despite severe drought conditions. Many types of predators were observed on the habitat plants. Because saffron blooms late in Vermont, no thrips were attracted, but honey bees were abundant demonstrating the value of this crop for supporting pollinators. The percentage of fractional green canopy cover (percent FGCC) in the saffron beds will be measured annually every July. Results will provide insights into the effect of habitat plants on insect pests on saffron and demonstrate the attractiveness of different flowering plants to beneficials.

Three sites infested with Russian knapweed were established to test the efficacy of mowing to increase the availability of suitable host material associated with late summer southern monsoon rains. Three plots in NW, NC, and SC New Mexico were established in May 2018 and monitored through 2021.  Limited regrowth occurred in July and August 2018 and 2019 with monsoon rains occurring at only one site.  The others had almost no regrowth after mowing.   

Objective 3:  Augment Natural Enemies to Increase Biological Control Efficacy.

Objective 3a.  Assess biological characteristics of natural enemies.

The European earwig is an important omnivorous predator in many agroecosystems, and can contribute to biological control in some crops.  Studies are being conducted of earwigs in California citrus to determine if this potential biological control agent might be generating direct damage to fruit, as it is an omnivore.  We found that this species, Forficula auricularia, is unfortunately an economically important direct pest of fruit on navel oranges and clementines (Citrus sinensis and Citrus clementina), whereas it is not a pest on true mandarins (Citrus reticulata).

Two resident parasitoid species that attack spotted wing drosophila were released in cane berry fields in the central coast of California; approximately 200,000 parasitoids were released over three months.

In 2018, an adventive population of the exotic parasitoid wasp, Trissolcus japonicus was discovered in Michigan. It is considered the most promising biological control agent against the brown marmorated stink bug (Halyomorpha halys). In 2020, augmentative releases of this wasp took place at 8 field sites in eastern Michigan. A total of 3,200 adult wasps were released. Trissolcus japonicus was recaptured at 3 sites, indicating reproduction in the field. There was also one recapture in 2020 from a field site where T. japonicus was released in 2019 indicating overwintering success.

Research determined the survival rate, longevity, and fecundity under various development temperatures for Gryon gonikopalense in host eggs of Bagrada hilaris in controlled conditions

Studies are attempting to characterize the volatile organic compounds from Russian knapweed found at different sites in New Mexico and determining which bioactive compounds influence the behavior of adult gall midges and wasps.

Investigations are underway for the chemical searching cues for Trichogramma papilionis. Related work looked at the effects of colony founder size on T. papilionis fitness.  Results showed that T. papilionis is attracted to volatile compounds released from sunn hemp leaves when eggs of Helicoverpa zea are laid on them. Other work demonstrated short-distance attraction to a specific blend of compounds identified, in olfactometer and greenhouse studies.

In 2021, studies continued in Hawaii on coffee berry borer.  Coffee has a multitude of scolytine (Coleoptera: Curculionidae: Scolitinae) pests including Hypothenemus hampei, coffee berry borer, which is a coffee pest of coffee,Hypothenemus obscurus, tropical nut borer, a significant pest of macadamia nut, and Xylosandrus compactus, black twig borer, a pest of many tropical and ornamental crops. The flat bark beetles, Carthartus quadricollis (Coleoptera: Silvanidae) and Leptophloeus sp. (Coleoptera; Laemophloeidae), are known to predate on coffee berry borer and tropical nut borer but their natural history (feeding habits, reproduction and movement) are poorly understood. Studies were conducted using molecular, field and laboratory assays to examine 1) flat bark beetle reproduction and movement in coffee and the broader agricultural landscape, 2) establishment of augmentative releases for biological control, and 3) predation rates on H. hampei, and, H. obscurus and X. compactus. Various life stages of Cathartus quadricollis and Leptophloeus sp. were found in seven different plant species common to the agricultural landscape around coffee farms, suggesting these predators are feeding and reproducing on theses hosts. Molecular analysis indicated that C. quadricollis and Leptophloeus sp. predated on H. hampei, H. obscurus and X. compactus in coffee, macadamia nut, and mixed coffee-macadamia nut farms. Laboratory reared predators were discovered near release sites on coffee farms at 1, 2, and 7 weeks after augmentative releases. Predation of Cathartus quadricollis on H. hampei eggs placed inside artificial coffee berries in coffee farms was about 40 percent. Flat bark beetle predators are significant natural enemies of scolytine pests in Hawaii and have excellent potential for augmentative releases.

Objective 3b.  Develop procedures for rearing, storing, quality control and release of natural enemies, and conduct experimental releases to assess feasibility.

Research has been conducted to develop a new and efficient rearing system for Nezara viridula (L.) and Trichopoda pennipes (Fab.) to enable the parasitoid to be used for augmentative biological control. The greatest challenge to using T. pennipes as an augmentative biological control agent is rearing a sufficient number of high-quality parasitoids for large-scale releases. Objectives of this study were to: 1) collect and efficiently rear N. viridula, 2) collect N. viridulaparasitized by T. pennipes, 3) optimize T. pennipes mating and oviposition, and 4) consistently rear high quality T. pennipes. For N. viridula, environmental conditions were determined, the diet was greatly simplified, and the best cage size and type was determined for each life stage. Mating was induced in T pennipes, N. viridula were parasitized, and parasitoid progeny were produced for multiple generations. Parasitism of T pennipes by N. viridula was compared between field and laboratory populations. This research will be described in a thesis and refereed publication.

Methods to rear the rosette weevil, Ceratapion basicorne, a biological control agent of yellow starthistle, Centaurea solstitialis, were developed by the USDA-ARS in Albany, CA.  The environmental requirements to terminate winter diapause were determined, and methods to use methoprene and 20-ecdysone to artificially initiate oviposition were discovered, which now permits rearing of multiple generations of this univoltine insect. Weevils were supplied to four non-USDA rearing laboratories, including two in Idaho and one in Colorado, as well as to the California Department of Food and Agriculture. 

Evaluation of rearing methods for the Guineagrass stem-borer, Buakea kaueae has been conducted.  The project was, so far, unsuccessful in rearing this specialist herbivore insect. 

A project evaluated membranes for artificial rearing of cattle fever ticks.  It was able to rear unfed nymphs to the engorged nymphal stage.

Researchers conducted a study on the impact of rearing on an alternative host on the host specificity of Psyttalia ponerophaga for biological control of Bactrocera oleae.

Experiments were performed to optimize cold storage conditions on survival and parasitism rate of Gryon gonikopalense in host eggs of Bagrada hilaris in controlled conditions

Mass-rearing methods for a parasitoid, Anagrus daanei, to be used against the Virginia creeper leafhopper (Cicadellidae: Erythroneura ziczac), were developed.  More than 30,000 parasitoids were successfully produced and reared.

Evaluations of inundative “bioherbicide” releases against leafy spurge continued. 

Techniques to utilize plant volatile organic compounds (VOCs) as a tool in host plant finding (yellow starthistle) and acceptance continues.  VOCs are collected in situ from bolting leaf tissue and from flowering stems of both yellow starthistle (YST) and Malta starthistle (MST) using a portable volatile collection system.  Gas chromatography-mass spectrometry (GC-MS) is used to analyze VOC profiles of YST and MST.  A y-tube olfactometer is used to conduct behavioral bioassays on existing and potential agents.  Airflow is maintained at 400 ml/min using a flowmeters on each arm of the olfactometer.  At the end of each arm, a 1 μl aliquot of eluted VOCs is placed on filter paper as an odor source.  As techniques are improved we should be able to help determine issues associated with host plant acceptance and variability in site establishment.

Objective 3c.  Implement augmentation programs and evaluate efficacy of natural enemies.

Many results have been reported under other objectives.  A few examples follow:

From 2018-2020 approximately 304,000 of the cosmopolitan pupal parasitoids Trichopria drosophilae and Pachycrepoideus vindemiae were released by the USDA-ARS in Albany, CA for control of spotted wing drosophila, Drosophila suzukii, in organic cane berry fields in Watsonville, CA. Although releases did not consistently increase parasitism levels, parasitism rates on some dates were far higher than in previous years, suggesting that releases did increase parasitism levels. This project also showed that rearing and releasing these parasitoids in large numbers is feasible.

Augmentation of entomopathogenic nematodes for eradication of cattle fever ticks on infested wildlife is in implementation mode in Texas.

A commercially available predatory m