Brief Summary of Minutes of Annual Meeting

The group met on November 18, 2016 on the Cornell campus in Ithaca, NY. We had 20 participants attending the meeting that was led and organized by Jennifer Thaler. Some of these participants had not joined the multistate group at that point and were interested in learning more about it. One important outcome is that all of the “external” participants are now part of our multistate group and are following up on the collaborations that they started during the meeting.

Since this was the first meeting of the group we dedicated half a day to talks designated to get to know the research interests of all participants. This was achieves by short 5 minute presentations of each participant that highlighted the areas of their research that were particularly relevant for this group.

The afternoon session was devoted to talking about potential future collaborations. We divided into thematic areas identified by the group as the most important areas that would be relevant for NYS agriculture and where chemical ecology could provide real solutions to current problems. Those thematic areas were:

• Domestication effects on plant resistance, plant-herbivore, plant-pollinators and plant-natural enemy interactions
• Multispecies interactions/interactions across tissues
• Context dependency of chemically mediated interactions from metabolic interactions to communities and landscape effects
• How to increase the adoption of chemical ecology tools by farmers and how to increase our communication with the public
• Non-target effects of pesticides
• Linking pollinator health to germplasm improvement.

The most important decisions that were made during this meeting, where:

• that the next organizational meeting was going to be located again in Ithaca, NY, since the location has a strong chemical ecology core group and is interesting for most participants to visit.
• that the chair of the Executive Committee for the next year was going to be Katja Poveda, the representative at large Andre Kessler and that Yolanda Chen would fulfill the role of secretary.
• that for our next organizational meeting the goal was to include the participation of farmers, as we wanted to look into the potential of submitting a USDA OREI (Organic Agriculture Research and Extension Initiative) to use push-pull techniques in the Northeast to reduce pest pressure, enhance biological control and ideally also enhance pollination. We did not take any decisions on the specific crop, but thought of potato, in a diversified system with vegetables and small berries as an ideal systems to pursue.

Outputs: The most significant outputs has been the writing of research proposal based on preliminary data gathered since the establishment of this multistate project. For example for the project focused on the control of herbivores of cucurbits, two new projects have been submitted (see below) and one has already been approved for funding. Also the first manuscripts have been submitted and even published during this time (for details see impact statement below). Most PI’s involved in this multistate have also disseminated their results at national conferences like the Ecological Society of America meeting and the Entomological Society of America meeting. PI’s have also interacted with farmers, and other stakeholders such a beekeepers and crop breeders, to start establishing means by which the performed research can be translated to tools and management strategies to protect pollinators, reduce pest pressure and increase yields. Our collaboration with the Northeast IPM center has also rendered us a piece in their newsletter (http://www.northeastipm.org/about-us/publications/ipm-insights/plants-have-natural-defense-systems/) that describes the objectives of this multistate and allows us to disseminate the importance of tools based on chemical ecology for more sustainable crop production.

Activities:

• Related with our first and second objective, the project focused on controlling herbivores of cucurbits (lead by Mike Mazourek, Cornell University) has developed assays for the highly sensitive quantification of cucurbitacins using SPE concentration and LC-MS. This technique is used for sampling squash seedlings that define different taxonomic groups including inter and intraspecific comparisons that differ in their degree of damage by striped cucumber beetles. No differences were found for true leaves although they are most conspicuously damaged plant tissue in the field and further they were below the detection thresholds of the herbivore. Cotelydon differences aligned with beetle preference and were within beetle detection thresholds. This group hypothesized that beetle preference in squash is not determined by cucurbitacin concentration. To test this hypothesis, they exposed young seedlings of highly preferred squash (golden zucchini) and compared damage to non-preferred squash seedlings (summer squash). Comparisons were performed with either cotyledon or true leaves removed. In each experiment the beetles preferred golden zucchini tissue over the corresponding tissue in summer squash. The group interpreted this to mean that beetle feeding preferences are determined by another factor, other than cucurbitacins. This group has also adapted high resolution carotenoid separation methods to our HPLC system and calibrated it with known standards. Experiments are underway to look at carotenoid accumulation in different plant tissues that also exhibit preference differences by striped cucumber beetles.
• Regarding our second objective (Define variability of chemically mediated interactions between pests, crops, and beneficial organisms in terms of plant chemistry, species interactions and landscape factors in the Northeast), one group lead by Jennifer Thaler and Katja Poveda started a project measuring the relationship between potato plants, Colorado potato beetles and their predators on organic farms in Central New York. These farms were chosen to reflect a gradient from low-levels of agriculture to high levels of agriculture in the surrounding landscape. Preliminary data indicate that herbivore responses to predators depend on the landscape complexity. Jennifer Thaler’s group also investigated the defensive responses of Colorado potato beetles to stink bug predators using a population of beetles from Ithaca, NY. They have found large decreases in feeding and growth of beetles when predators are present but not consuming beetles. Combining these results is an advance in understanding the causes of variation in the predator-prey interaction and will be helpful in designing biological control practices in the future.
• In the front of pollinator research Lynn Adler has been leading an effort to understand how pollinator populations can be supported based on the quality of the host plants. This past year, they discovered that the medicinal value of sunflower pollen extends to a wide range of sunflower cultivars, wild sunflower accessions, two other Helianthus congeners, and even two Solidago species, which are in the same family as sunflower but not very close relatives. This discovery suggests that a wide range of sunflower relatives may be beneficial to the common eastern bumble bee and useful for treating Crithidia infection.
• The group lead by Richard Karban in this past year has learned how to make more effective use of volatile communication to induce resistance against insect herbivores. Specifically, they have learned that variation in the nutritional quality of crops can reduce the efficiency and success of herbivores across many different species of plants and insects. They also identified important sources of variation in plant quality in their model system for plant communication, Artemisia tridentata. Individuals vary in the major chemicals that they emit when they are attacked or damaged. This chemotypic variation affects how effectively they respond to cues of damage. The effectiveness of communication also is affected by the geographic proximity of the source of volatile cue, suggesting that plant cues may exhibit geographic dialects.
• Anurag Agrawal’s groups has been investigating ways to aid to the conservation of non-target organisms such as the monarch butterfly to agricultural practices, specifically the use of herbicides. Specifically they are investigating the use of swallow-worts by monarch butterflies, which are used for oviposition but do not support caterpillars. In this project they are investigating the use of swallow-worts by monarchs, the chemical cues used by monarchs to recognize them, and the impacts of reduced milkweed availability due to herbicide usage on their preferences. Initial experiments showed reduced oviposition on swallow-wort in the presence of milkweed. Chemical analyses are currently underway. 
• Cesar Rodriguez-Saona’s group at Rutgers has been applying chemical ecology techniques to understand the defensive traits of plants to the false blossom disease. Last year they evaluated the molecular and biochemical changes associated with plant defensive traits in cranberries affected by the false blossom disease and the preference and performance of its insect vector (blunt-nosed leafhoppers) and leaf chewers (spotted fireworm, Sparganothis fruitworm, and gypsy moth) on plants infected by false blossom disease.
• This same groups has been very active at development management tools based in behavior-manipulation to control the invasive pest spotted wing drosophila (SWD) in blueberries. These studies involved the use of attracticidal red spheres that incorporate a toxin, a phagostimulant, and a visual stimulus. Experiments were conducted to evaluate: a) the effects of pattern of placement of spheres within fields (grid versus border) in reducing SWD infestation, and b) the effects of location of spheres within a bush (top versus bottom) in reducing SWD infestation. Studies were also conducted using a new sprayable attract-and-kill formulation, SPLAT SWD, to reduce SWD infestation. SPLAT SWD was applied alone or in combination with organic insecticides in blueberry fields. In addition studies were conducted to investigate the response of SWD to odors from various sources including fermentation, yeast, and leaves. These studies were conducted under laboratory and field conditions.
• The group of Andre Kessler studied how biotic and abiotic environmental factors influence chemical information transfer and plant secondary metabolism-mediated interactions with other organisms. This past year, they focused on three key projects, namely A) the effects of temperature and humidity on the information : noise ratio in volatile organic compound (VOC) signaling, B) the effects of certain soil elements, such as As and Si on constitutive and inducible plant secondary metabolism and herbivore resistance, and c) the role of VOC signaling on mediating complex community dynamics and plant fitness outcomes. One major finding from the Datura wrightii study system is that the emission of certain plant VOCs is primarily altered by abiotic stresses, while others are emitted specifically in response to biotic stresses, such as herbivory. This means that VOC-mediated chemical information is encoded in distinct channels allowing interacting organisms to very specifically extract information about the plant’s physiological and metabolic status. In another study with cucumber, the group found a major induced resistance-mediating effect of Si. Plants grown in soils with minimal Si-content were not able to induce resistance in response to herbivore attack. Current work focuses on the effects of Si on direct and indirect resistance traits as well as the mechanisms underlying the priming effect. Lastly, research associated with this Multistate project that focused on modeling chemical information transfer revealed VOC-mediated chemical information transfer has a stabilizing effect on community dynamics.

Milestones reached:

As a group we have reached several milestones pertaining to our different objectives. Most activities have been focusing on defining the variability of chemical mediated interactions between pests, crops and beneficial organisms in terms of plants chemistry, species interaction and landscape factors in the Northeast (Objective 2). Here we have an overall better understanding of which chemical cues are mediating interaction between cucumbers and their herbivores, how the landscape is shaping interaction between crops, herbivore pests, and predators, how plant quality can affect pollinator health and how the quality of the crop influence their interactions with herbivores. Regarding our second objective on developing chemical ecology tools and information to support sustainable agriculture by reducing damage by pests in crops such as potatoes, brassicas, cucurbits, apples, blueberries, and sweet corn, while maintaining pollinator health in agricultural systems we have definitively started to identify the main chemical cues that are involved in important interaction between plants and their pests or vectors of important diseases. Mostly for blueberry there are promising tools that can help control Spotted wing Drosophila, while other information could be used to hopefully be soon used as tools for more sustainable agriculture. Our 5^th objective of establishing a chemical ecology analytical facility in the Northeast definitively is on their way and expertise among members of this multistate have allowed for shared technical expertise and equipment.

Glaum P. and A. Kessler. 2017. Functional reduction in pollination services through Herbivore-Induced Pollinator Limitation and its potential in mutualist communities. Nature Communications. in press

Claflin, S, Jones, L, Thaler, J, Power, A. 2016. Crop-dominated landscapes have higher vector-borne plant virus prevalence. Journal of Applied Ecology. 10.1111/1365-2664.12831