Brief Summary of Minutes of Annual Meeting

WERA 1021 Accomplishments:

Objective 1: Improve our understanding of SWD populations and develop tools to accurately predict SWD risk.

Given the polyphagous nature of this pest, a central theme in recent SWD research has been on population monitoring in alternative hosts. Trapping efforts have been increasingly concentrated in wild areas, with honeysuckle proving to be an especially important host. On the other hand, some commercial hosts have been more carefully examined in light of grower concerns (e.g., tart cherries). Researchers have increasingly recognized, however, that trapping networks are not always sufficient to accurate predict risks of SWD infestation to fruit growers; therefore, increased efforts were made to implement in-fruit larval sampling in commercial crops. This additional information was communicated directly to growers.

Objective 2: Optimize use of pesticides to reduce reliance upon them and disruption of beneficials.

Several aspects of SWD biology and management suggest that the risk of insecticide resistance in this pest is of paramount concern: (1) therapeutic insecticide use remains the primary management approach, with a ‘zero-tolerance’ threshold for pest presence; (2) SWD has numerous generations per year, which could accelerate the rate of resistance spread; and (3) documentation of lower susceptibility to spinosad in California SWD populations. Participating researchers have responded to this threat through the development and implementation of the RAPID assessment method for insecticide susceptibility. In addition, researchers have been examining both new products for SWD control (e.g., Spear-T derived from spider venom; essential oils as repellents), as well as techniques that may increase the effectiveness of current products (e.g., adding feeding stimulants to increase effectiveness of marginally-effective insecticides; modifications of equipment to increase spray coverage). Taken together, these efforts illustrate the effectiveness of collaborative research in both the development of novel chemical treatments and the preservation of existing options.

Objective 3: Develop non-pesticide based tactics for SWD management and evaluate sustainable SWD management programs to provide best management practices for SWD.

The heavy reliance on chemical control for SWD has made the development of non-chemical control strategies a critical research goal. Several different strategies have been investigated by participating researchers, including (but not limited to):

• Exclusion via mesh netting. While this technique has consistently shown promise in the reduction of SWD infestation levels in various crops, researchers have also noted important considerations in the future refinement of this method. These include: (1) inability to prevent all infestations (likely due to volunteer fruit); and (2) the need to add pollinators to maintain yield.

• Mulches and soil amendments. Black plastic mulch has been shown to be an effective agent of microclimatic change that is detrimental to SWD. One particularly interesting mechanism is its potential as a barrier to soil pupation by SWD larvae. Furthermore, preliminary research is ongoing to assess the potential effects of biochar on SWD management. This soil additive has many benefits (e.g., C-sequestration; water and nutrient retention), however, its impact on SWD management is unknown.

• Changes in crop architecture. A major emphasis was placed this year on the impacts of pruning on SWD infestations. Results appear mixed so far; while some studies suggest no clear reduction in SWD infestations due to pruning, other studies in cherries and highbush blueberries report sufficient microclimatic changes to reduce larval populations (in cherries, for example, the removal of 10 limbs is needed to gain this benefit, coupled with regular mowing).

• Biological control. The effectiveness of native parasitoid wasps against SWD continue to be monitored to provide a baseline for potential future classical biological control releases. In addition, the nitidulid Glischrochilus quadrisignatus may contribute to natural levels of SWD mortality. Preliminary studies show that infested blueberries were nearly completely devoured in the presence of this beetle.

Objective 4: Coordinate grant-funded research and extension efforts to minimize redundancy and ensure knowledge transfer.

The SWD community has continued to embrace the philosophy of coordinated efforts, both in the research and extension arenas. Several multiregional grants have been pursued this year, and information has been shared within regions in a timely fashion (e.g., extension updates within North Central region; maintenance of Northeast IPM SWD Working Group). Ensuring of knowledge transfer to end-users has also been a major goal. For example, Michigan State University has employed a Systems Science approach to SWD management, with one key recent outcome being targeted training in viewing insecticide recommendations as dynamic versus prescriptive. The results of this training are particularly encouraging, with growers showing decreased pest levels and treatment costs.