Multi-Life Stage Management Project for Plum Curculio Underway
In 2009, Leskey et al. received funding from the NIFA Specialty Crops Initiative Program to develop a multi-lifestage approach for managing plum curculio. Essentially this project is designed to move away from management programs that were first developed based on a intensively managing a perennial monoculture because this design has had unforeseen consequences for pest management in that horticultural uniformity leads to temporally and spatially homogenous resource distribution requiring protection based on whole-orchard insecticide applications.
We believe that the biological and ecological foundation of insect behavior offers a clear opportunity to transform indiscriminate management practices for control of insect pests. In this case, behaviorally active stimuli for plum curculio, Conotrachelus nenuphar (Herbst), a key pest of deciduous tree fruit, will be identified and subsequently manipulated to attract and retain adults within particular locations within the orchard to allow for implementation of spatially precise control strategies, thereby reducing insecticide inputs and production costs, increasing sustainability of the cropping system, and promoting ecological benefits and marketing opportunities.
The basis for this novel approach is referred to the baited trap-tree management strategy, and is rooted in attract-and-kill management within a spatially precise area. By baiting select perimeter row apple trees with attractants, plum curculios will aggregate within these specific baited perimeter-row trees. Then by applying insecticides to only those baited trap trees located on the periphery of apple orchards rather than the entire perimeter row or the entire orchard (after petal fall), tremendous reductions in the amount of insecticide applied can be achieved without compromising plum curculio control. This strategy has resulted in a ~70% and 93% reduction in the total percentage of trees treated with insecticide compared with perimeter row sprays and standard whole-orchard sprays, respectively.
Currently, we are working toward isolating and identifying candidate olfactory stimuli associated with host- and mate-finding for plum curculio using gas chromatography coupled with electroantennogram detection (GC-EAD) that will lead to novel lures to improve attractiveness of trap trees. Secondly, we are developing effective deployment strategies for newly identified stimuli or lures to manipulate host- and mate-finding behavior and promote aggregation of plum curculio within trap trees in commercial apple orchards. We also are evaluating efficacy of entomopathogenic nematodes (EPNs) against plum curculio larvae. These EPNs will be used to target larvae generated from infested fruit falling from trap trees. Ultimately, we will evaluate the efficacy of this multi-life stage approach for management of plum curculio.
2011 RESEARCH UPDATE
Broad Laboratory Screening of Entomopathogenic Nematodes for Control of Plum Curculio, Conotrachelus nenuphar.
Shapiro-Ilan1, David I., T. C. Leskey2, and S.E. Wright2. 1USDA-ARS, SE Fruit and Tree Nut Research Laboratory, 21 Dunbar Rd., Byron, GA 31008, 2USDA-ARS, Appalachian Fruit Research Station, 2217 Wiltshire Road, Kearneysville WV, 25430.
The plum curculio, Conotrachelus nenuphar, is a major pest of stone and pome fruit in North America. Current control recommendations for C. nenuphar consist solely of above-ground applications of chemical insecticides to suppress adults. Due to environmental and regulatory concerns, research on developing alternative control strategies is warranted. Our overall goal is to develop a sustainable multi-stage strategy control C. nenuphar. Part of the strategy entails the use of entomopathogenic nematodes (Steinernema spp. and Heterorhabditis spp.) to control the pest’s soil-dwelling stages. In prior research, we established that soil applications of Steinernema riobrave can result in high levels of control (78-100%) when targeting C. nenuphar larvae in Southeastern peach orchards. Conceivably, when the technology is applied in other regions of the US, e.g., the Northeast, a different nematode may be more appropriate due to varying soil temperatures and other parameters. Therefore, the objective of this study was to conduct a broad laboratory screening experiment to select nematodes for use against C. nenuphar in the Northeastern US. Using soil cups containing C. nenuphar larvae, we compared the virulence of 13 steinernematid and heterorhabditid strains (comprising eight species) in two different soils (from NH and WV) and at three temperatures (12 °C, 18 °C, and 25 °C). Depending on the soil type and temperature, a number of strains exhibited high levels of virulence including H. bacteriophora (Oswego), H. indica (HOM1), S. feltiae (SN), S. kraussei, S. rarum (17C&E), and S. riobrave (355). Overall, S. feltiae (SN), S. rarum (17C&E), and S. riobrave (355) appear to be the most promising candidates for use against C. nenuphar in the Northeast (though S. riobrave did not perform as well at the lower temperatures). In future research, we will test the most promising nematodes under various field conditions, and determine their potential for use in an integrated C. nenuphar management approach.