methods-for-rearing-parasitoid-ganaspis-brasiliensis-promising

Methods for Rearing the Parasitoid <em>Ganaspis brasiliensis</em>, a Promising Biological Control Agent for the Invasive <em>Drosophila suzukii</em>

Native to East Asia, the spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), has established widely in the Americas, Europe, ...

University of California Berkeley

Biological control is widely successful at controlling pests, but effective biocontrol agents are now more difficult to import from countries of origin due to more restrictive international trade laws (the Nagoya Protocol). Coupled with increasing demand, the efficacy of existing and new biocontrol agents needs to be improved with genetic and genomic approaches. Although they have been underutilised in the past, application of genetic and genomic techniques is becoming more feasible from both technological and economic perspectives. We review current methods and provide a framework for using them. First, it is necessary to identify which biocontrol trait to select and in what direction. Next, the genes or markers linked to these traits need be determined, including how to implement this information into a selective breeding program. Choosing a trait can be assisted by modelling to account for the proper agro-ecological context, and by knowing which traits have sufficiently high heritability values. We provide guidelines for designing genomic strategies in biocontrol programs, which depend on the organism, budget, and desired objective. Genomic approaches start with genome sequencing and assembly. We provide a guide for deciding the most successful sequencing strategy for biocontrol agents. Gene discovery involves quantitative trait loci analyses, transcriptomic and proteomic studies, and gene editing. Improving biocontrol practices includes marker-assisted selection, genomic selection and microbiome manipulation of biocontrol agents, and monitoring for genetic variation during rearing and post-release. We conclude by identifying the most promising applications of genetic and genomic methods to improve biological control efficacy.

Next-generation biological control: the need for integrating genetics and genomics.

California currently produces about a quarter of the world's pistachios. Pistachio nuts are susceptible to feeding by stink bugs and leaffooted bugs; therefore, the invasive presence of the highly polyphagous brown marmorated stink bug,  (Stål) (Hemiptera: Pentatomidae), is a concern to California pistachio growers. We aimed to assess the potential of  to cause yield loss and nut damage to pistachios, which had not yet been assessed in the field. Over two years, terminal branch ends with pistachio clusters were enclosed in organdy cages from spring to fall and exposed to either , the native stink bug  Say (Hemiptera: Pentatomidae), or leaffooted bug  (Dallas) (Hemiptera: Coreidae), for 4-7-day feeding periods at different times of the season. We found that  adults cause more epicarp lesions (external damage) when recorded at harvest time than the native species. They did not, however, cause more kernel necrosis (internal damage) than the two native species tested, which is a more relevant damage criterion for commercial production. There were no differences among insect species for any other recorded damage criteria. We conclude that  could cause similar damage as the native species but note that  population densities in California are still low and future damage levels will be dependent on this pest's population density.

Comparing the Feeding Damage of the Invasive Brown Marmorated Stink Bug to a Native Stink Bug and Leaffooted Bug on California Pistachios.

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is a polyphagous insect pest that has invaded much of the United States, including California. Despite model predictions that regions in California like the agriculturally important Central Valley are suitable, H. halys populations and the occurring crop damage are distinctly lower than in regions of the East Coast. To evaluate if this is due to low nymphal survival in the high temperature and intensive monoculture environment, H. halys nymphs were caged on four common Central Valley tree crops: almond, pistachio, peach, and grape, and compared to the well-established almond and pistachio pest Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae). Nymphal development showed that peach, almond, and pistachio can sustain H. halys as single host plants until adult eclosion, whereas grapes cannot. The addition of fruiting structures of almond, pistachio, and grape to H. halys caged on peach trees (= mixed diet) did not increase nymphal survival but did increase adult female size. Leptoglossus zonatus survival was higher than H. halys on pistachio, but not on the other crops. Overall, H. halys nymphal mortality in the field was high, with 92% in the mixed diet compared to 73% in the mixed diet control in the laboratory, indicating abiotic population pressures. Our results confirm peach as a good H. halys host plant and suggest that almond has a similar suitability, and while pistachios can support H. halys nymphal development, they seem less likely to facilitate population growth.

Article	Year
Next-generation biological control: the need for integrating genetics and genomics. Biological reviews of the Cambridge Philosophical Society\| PubMed ID: 32794644	2020
Comparing the Feeding Damage of the Invasive Brown Marmorated Stink Bug to a Native Stink Bug and Leaffooted Bug on California Pistachios. Insects\| PubMed ID: 33053666	2020
Field Survival of the Brown Marmorated Stink Bug Halyomorpha halys (Hemiptera: Pentatomidae) on California Tree Crops. Environmental entomology\| PubMed ID: 34175919	2021

Judith M. Stahl

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