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Building on an exercise that identified potential harms from simulated investigational releases of a population suppression gene drive for malaria vector control, a series of online workshops identified nine recommendations to advance future environmental risk assessment of gene drive applications.

Genetically engineered gene drives (geGD) are potentially powerful tools for suppressing or even eradicating populations of pest insects. Before living geGD insects can be released into the environment, they must pass an environmental risk assessment to ensure that their release will not cause unacceptable harm to non‐targeted entities of the environment. A key research question concerns the likelihood that nontarget species will acquire the functional GD elements; such acquisition could lead to reduced abundance or loss of those species and to a disruption of the ecosystem services they provide. The main route for gene flow is through hybridization between the geGD insect strain and closely related species that co‐occur in the area of release and its expected dispersal. Using the invasive spotted‐wing drosophila, Drosophila suzukii, as a case study, we provide a generally applicable strategy on how a combination of interspecific hybridization experiments, behavioral observations, and molecular genetic analyses can be used to assess the potential for hybridization. [ABSTRACT FROM AUTHOR]

Genetically engineered (GE) cotton, MON 88702, is protected against certain sucking pests, such as plant bugs and thrips, by producing mCry51Aa2, a modified protein from Bacillus thuringiensis (Bt). Predatory pirate bugs (Orius spp.), natural enemies contributing to biological pest control, are also sensitive to the insecticidal protein when exposed continuously to high concentrations. We evaluated effects of MON 88702 on Orius majusculus when fed prey types with different mCry51Aa2 concentrations. When neonates were provided exclusively Tetranychus urticae spider mites reared on MON 88702 (high mCry51Aa2 content), adverse effects on predator survival and development were confirmed, compared with specimens fed prey from near‐isogenic non‐Bt cotton. When fed a mixture of T. urticae and Ephestia kuehniella eggs (mCry51Aa2‐free), predator life table parameters were similar to the treatment where eggs were fed exclusively. When mCry51Aa2‐containing spider mites were provided for a limited time at the beginning or the end of juvenile development, effects were less pronounced. While pirate bug nymphs showed similar consumption rates for prey from Bt and non‐Bt cotton, choice experiments revealed a preference for E. kuehniella eggs over spider mites. Lepidopteran larvae (Spodoptera littoralis, high mCry51Aa2 content) or cotton aphids (Aphis gossypii, mCry51Aa2‐free) reared on MON 88702 as alternative prey did not result in adverse effects on O. majusculus. Our study suggests limited risk of mCry51Aa2‐producing cotton for O. majusculus, because its sensitivity for the Bt protein is relatively low and its natural food consists of diverse prey species with varying concentrations of Bt protein. [ABSTRACT FROM AUTHOR]

BACKGROUND: Combining different biocontrol agents, particularly micro‐ and macroorganisms, can contribute to new and sustainable pest control approaches. Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the most destructive pests of solanaceous crops. An emerging management strategy consists of biological control using microbial insecticides such as baculoviruses, but with limited efficacy. Thanks to their high target specificity, baculoviruses can be used simultaneously with natural enemies such as parasitoids for improved control of T. absoluta. However, potential indirect nontarget effects of baculoviruses on parasitoids can result from overlapping resource requirements. We assessed whether ovipositing parasitoid females discriminated against virus‐treated hosts and examined the outcome of within‐host competition between the hymenopteran parasitoids Necremnus tutae (Reuter) (Eulophidae) and Dolichogenidea gelechiidivoris Marsch (Braconidae), and the Phthorimaea operculella granulovirus (PhopGV, Baculoviridae) that infects T. absoluta larvae. RESULTS: Female D. gelechiidivoris discriminated against virus‐treated hosts, whereas N. tutae did not. We found few indirect virus‐related effects depending on the species, the sex, and the time of virus treatment. Effects were ambivalent for D. gelechiidivoris offspring and ranged from increased male longevity when infection occurred before parasitization to reduced emergence and male longevity when infection occurred after parasitization. N. tutae offspring showed a longer development time and shorter male longevity when they developed in virus‐treated hosts. CONCLUSION: The virus had a low impact on parasitoid offspring. In rare cases, adverse effects were detected; however, the low magnitude of these effects is unlikely to reduce the fitness of parasitoid offspring, therefore both parasitoids seem compatible with the baculovirus for control of T. absoluta. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The complete netting of orchards is one strategy to protect fruit trees from pest and pathogen damage by reducing insect movement. When the cultivated trees were derived from genetic engineering (GE), reduced pollinator movement may also reduce outcrossing to cultivated or wild non-GE trees. We report on a field study over four years in a plot of apple tress supplied with insect side nets and covered with hail nets that were closed from shortly before flowering to harvest. A reduced number of arthropods in general, and large bees in particular, were recorded inside the netted plot compared with outside. However, wild bees colonized the plot before the net was closed and built up populations inside. An additional experiment demonstrated that small bees were able to cross the hail net. While the nets were effective in excluding large bees as active pollen vectors, the proportion of small bees acting as such remained unquantified. Furthermore, a companion study showed occasional cross-pollination events through the netting. For the field release of GE apple trees, acceptable levels of outcrossing thus need to be defined. [ABSTRACT FROM AUTHOR]

Host selection behavior is a key aspect of parasitoid foraging. Elucidating the host selection behaviors of a hymenopteran parasitoid on different hosts can clarify the interactions between the parasitoid and its hosts and further promote the development of biological control strategies utilizing this parasitoid. In the current study, we investigated the host-selection behavior of a predominant host-feeding parasitoid, Necremnus tutae Ribes & Bernardo (Hymenoptera: Eulophidae), on different instars of Tuta absoluta (Meyrick) larvae. We identified and described four host-selection behaviors of N. tutae: host feeding, oviposition, host killing and rejection. Ovipositor insertion was divided into three behavioral elements: ovipositor stabbing, ovipositor stirring and egg laying. This behavioral pattern facilitated the quick distinction of host-selection behaviors in a host-feeding parasitoid. Furthermore, we found that N. tutae directly fed on hosts of all instars but preferred 1st–2nd-instar hosts for feeding and 3rd-instar hosts for laying eggs. The duration of both host feeding and oviposition increased with larval host age. Further analysis revealed that the duration and frequency of two main behavioral elements of host-feeding behavior (ovipositor stirring and feeding on the host) also increased with larval host age. Understanding these basic behavioral traits is fundamental for developing parasite-rearing schedules and glasshouse introduction methods. [ABSTRACT FROM AUTHOR]

Optimizing assimilate partitioning to wheat grains is important to improve grain size and filling. Manipulation of gene expression of assimilate transporters is promising to improve uptake capacity and partitioning. The barley sucrose transporter HvSUT1 has been ectopically expressed in winter wheat controlled by the barley Hordein B1 promoter (HOSUT lines). In greenhouse experiments, HOSUT lines produced lager grains and higher grain yields than the untransformed control cultivar 'Certo'. This study aimed to evaluate and verify the potential of three HOSUT lines regarding grain yield and quality under field conditions. A three-year field trial in Switzerland using up to three N fertilization levels was performed. In addition to the three HOSUT lines and 'Certo', three Swiss reference lines were tested. Yield parameters, grain composition, phenology and disease scores were recorded. Grain weight was increased for HOSUT lines by 3–8 % compared to wildtype 'Certo', whereas grain number per spike was reduced by 4–12 %. Thus overall, grain yield per area remained largely unchanged. However, higher levels of iron and zinc found in HOSUT grains could be health-promoting. No negative unintended effects on chemical composition, disease susceptibility, and plant phenology were detected, with the exception of complete anther retention in one of the three HOSUT lines. While stimulation of sucrose uptake and/or partitioning in HOSUT lines resulted in higher grain size, an increase of total grain yield may only be achieved if trade-offs between grain size and grain number are overcome. The study contributes to the understanding of sucrose transporter modifications in wheat. It demonstrates the importance of field-testing crop plants that exhibit promising traits under controlled environments. More research is needed to identify the bottlenecks that appear under field conditions to unlock the potential of the HOSUT strategy for agronomic application. • Transgenic HOSUT wheat expresses a barley sucrose transporter to improve grain assimilate uptake. • 3 HOSUT lines were field tested in a 3-year yield trial in Switzerland with different N-levels. • HOSUT grains were heavier compared to wildtype (Certo), but spikes contained fewer grains. • To obtain higher yields, trade-offs between grain size and grain number need to be overcome. [ABSTRACT FROM AUTHOR]

Background: Phthorimaea absoluta, a highly destructive invasive pest, poses a significant threat to tomato production globally. Exploring alternative control methods, such as host plant resistance can contribute to diminish reliance on insecticides and promote sustainable integrated pest management (IPM) practices. Thus, the identification of new P. absoluta-resistant tomato cultivars and potential wild sources for breeding programmes remains imperative. We evaluated the effect of 19 tomato genotypes, comprising 16 domesticated varieties and three wild tomato species, on oviposition output of female P. absoluta, as well as on larval performance under no-choice conditions using detached leaves. We also characterized and quantified glandular and nonglandular trichomes, exploring their potential correlation with the response of P. absoluta to the tomato plants., Results: Generally, fewer eggs were oviposited on domesticated plants, whereas the wild tomatoes Solanum arcanum and S. neorickii and the domesticated tomato Corona F1 impaired larval development. The pest larvae consumed a limited area of leaflets from S. arcanum and S. neorickii compared to other genotypes, leading to the lowest weights in both male and female pupae. All tomato plants exhibited a prevalence of nonglandular over glandular trichomes, except for S. arcanum, which exhibited a higher abundance of glandular trichomes. Although higher trichome density correlated with longer larval settlement on the leaflets, it did not influence female oviposition., Conclusion: Our findings demonstrate that the wild tomatoes S. arcanum and S. neorickii could be considered as potential sources for breeding programmes, and the domesticated Corona F1 could offer IPM options against P. absoluta. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

Genetically engineered gene drives (geGD) are potentially powerful tools for suppressing or even eradicating populations of pest insects. Before living geGD insects can be released into the environment, they must pass an environmental risk assessment to ensure that their release will not cause unacceptable harm to non-targeted entities of the environment. A key research question concerns the likelihood that nontarget species will acquire the functional GD elements; such acquisition could lead to reduced abundance or loss of those species and to a disruption of the ecosystem services they provide. The main route for gene flow is through hybridization between the geGD insect strain and closely related species that co-occur in the area of release and its expected dispersal. Using the invasive spotted-wing drosophila, Drosophila suzukii, as a case study, we provide a generally applicable strategy on how a combination of interspecific hybridization experiments, behavioral observations, and molecular genetic analyses can be used to assess the potential for hybridization., (© 2023 The Authors. Risk Analysis published by Wiley Periodicals LLC on behalf of Society for Risk Analysis.)