Project Number: 8010-22000-033-052-I
Project Type: Interagency Reimbursable Agreement
Start Date: May 1, 2021
End Date: Nov 15, 2022
The ultimate outcome of the proposed research is to limit or reduce population growth of BMSB populations through wider regional establishment and distribution of a safe and effective, adapted natural enemy of BMSB (Trissolcus japonicus). Objective: 1) Determine the numbers of parasitoids to be field released and the corresponding BMSB host density for optimal parasitoid establishment at a location. Objective 2) Evaluate the influence and impact of kairomone traces deposited on host plant foliage by BMSB and select non-target species on parasitism by T. japonicus under field conditions. Objective 3) Conduct surveys for the presence of endosymbiotic Wolbachia in adventive T. japonicus populations, and if found, determine their impact on parasitoid efficacy. Objective 4) Study the relative impact of long- vs. short-distance semiochemical cues on parasitoid foraging behavior.
Obj. 1) Parasitoid numbers and BMSB density for optimal parasitoid establishment. Conduct redistribution of T. japonicus and associated field experiments, egg mass surveys and sentinel egg mass placements when BMSB occurs in the field. Redistribute Delaware populations of T. japonicus with lab-reared material to evaluate local establishment. Monitoring of low and high-release numbers per site will be compared at different release locations across Delaware, along with control sites with no release and following pre-release surveys to show that T. japonicus is still absent from the proposed release sites. Conduct season-long sampling for potential parasitism of non-target stink bugs at release and control sites. Investigate local-scale retention, host finding and dispersal by using arrays of potted maple trees. Parasitoids will be released onto a tree at the center of the array and their movement outwards to adjacent trees will be monitored. Obj. 2) Surveys for the presence of endosymbiotic Wolbachia in adventive T. japonicus populations, and if found, determine their impact on parasitoid efficacy. Three T. japonicus subpopulations are known: 1) New York, 2) mid-Atlantic, and 3) West Coast haplotypes. Evaluate samples of T. japonicus from multiple locations of all three haplotypes to detect and characterize Wolbachia. Screen for Wolbachia using the primers Universal (WspF & WspR) and Supergroup A (Wsp81F & Wsp691R). Assay initial presence/absence of Wolbachia using PCR-based assays and gel electrophoresis. If detected, sequences will be generated at the Univ. Delaware DNA Center and compared to known sequence reads. If detected, characterize the effects of the bacterial infections on wasp longevity, searching behavior and fecundity. Obj. 3) Influence and impact of kairomone deposited on foliage by BMSB and non-target species on parasitism by T. japonicus. Conduct behavioral assays with field experiments during the summer months when field populations of T. japonicus are naturally foraging for BMSB egg masses. Test varying concentrations and ratios of the known kairomone components and the effect of secondary components present at low amounts in the kairomone blend. Identify the optimal blend of known chemical constituents of contact kairomones to enhance T. japonicus foraging behavior. Evaluate impact of kairomones on BMSB and non-target stink bug parasitism under field conditions. Conduct a mass release of T. japonicus to increase parasitism, and assess the effects of contact kairomone. Investigate local-scale retention, host finding and dispersal as influenced by the presence of kairomone or its individual components by using arrays of potted maple trees with sentinel egg masses of BMSB and spined soldier bug. Obj. 4) Impact of long- vs. short-distance semiochemical cues on parasitoid foraging behavior. Evaluate impacts of BMSB-induced plant volatiles and contact kairomones on T. japonicus foraging. Compare effects of volatile and contact semiochemicals in the field. Look at impact of herbivore-induced plant volatiles & stink bug contact kairomones. Egg masses will be placed on a grid with semiochemical cues applied during the field season.