Trisna Dewi Tungadi

Drosophila suzukii is a globally invasive pest that lays eggs in ripening fruit, causing degradation through larval feeding and significant economic losses. Control of D. suzukii relies on integrated pest management, combining cultural, biological and chemical methods, with insecticide applications serving as a final line of defence. This study investigated whether regular insecticide use in United Kingdom (UK) soft-fruit crops resulted in reduced between- and within-year susceptibility of D. suzukii to three commonly used insecticides. Field-collected D. suzukii were used to establish laboratory strains from summer collections in 2019, 2020 and 2021, and autumn collections in 2020. Strains were reared for 8–10 generations before exposure to a range of concentrations of cyantraniliprole, lambda-cyhalothrin and spinosad in mortality bioassays. No consistent directional increase in LC₅₀ was observed across the three sampling years. However, more than half of the strains established from autumn 2020 collections showed reduced susceptibility to some insecticides compared with strains from the same locations collected four months earlier, with a 1.4–2.1-fold increase in LC₅₀. These results indicate generally stable susceptibility in UK populations while highlighting the value of continued resistance monitoring.

Common bean (Phaseolus vulgaris L.), the world’s most widely grown legume crop, is not only of great commercial importance but is also a vital smallholder crop in low-to-medium-income countries. In sub-Saharan Africa common bean provides consumers with a major proportion of their dietary protein and micronutrients. However, productivity is constrained by viruses, particularly those vectored by aphids and whiteflies, and problems are further compounded by seed-borne transmission. We describe common bean’s major viral threats including the aphid-transmitted RNA viruses bean common mosaic virus and bean common mosaic necrosis virus, and the whitefly-transmitted begomoviruses bean golden mosaic virus and bean golden yellow mosaic virus and discuss how high-throughput sequencing is revealing emerging threats. We discuss how recent work on indirect and direct viral ‘manipulation’ of vector behaviour is influencing modelling of viral epidemics. Viral extended phenotypes also modify legume interactions with beneficial organisms including root-associated microbes, pollinators and the natural enemies of vectors. While problems with common bean tissue culture have constrained transgenic and gene editing approaches to crop protection, topical application of double-stranded RNA molecules could provide a practical protection system compatible with the wide diversity of common bean lines grown in sub-Saharan Africa.

Drosophila suzukii (Matsumura) or spotted wing Drosophila is a worldwide invasive pest of soft‐ and stone‐fruit production. Female D. suzukii lay their eggs in ripening fruit and the hatched larvae damage fruit from the inside, rendering it unmarketable and causing significant economic loss. Current methods to reduce D. suzukii population in the field primarily rely on chemical insecticides which are not a sustainable long‐term solution and increase the risk of resistance developing. Several studies demonstrate that when D. suzukii encounter or coexist with other Drosophila on a food source, this is usually a disadvantage to D. suzukii, leading to reduced oviposition and increased larval mortality. These effects have potential to be exploited from a pest management perspective. In this review we summarise recent research articles focusing on the interspecific interactions between D. suzukii and other Drosophila species aimed at understanding how this drives D. suzukii behaviour. Potential semiochemical and microbiome impacts are postulated as determinants of D. suzukii behaviour. Development of control practices focusing on reducing D. suzukii populations and deterring them from laying eggs by utilising factors that drive their behaviour are discussed. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Cucumber mosaic virus (CMV), a major tomato pathogen, is aphid-vectored in the non-persistent manner. We investigated if CMV-induced volatile organic compounds (VOCs) or other virus-induced cues alter aphid–tomato interactions. Y-tube olfactometry showed that VOCs emitted by plants infected with CMV (strain Fny) attracted generalist (Myzus persicae) and Solanaceae specialist (Macrosiphum euphorbiae) aphids. Myzus persicae preferred settling on infected plants (3 days post-inoculation: dpi) at 1h post-release, but at 9 and 21 dpi, aphids preferentially settled on mock-inoculated plants. Macrosiphum euphorbiae showed no strong preference for mock-inoculated versus infected plants at 3 dpi but settled preferentially on mock-inoculated plants at 9 and 21 dpi. In darkness aphids showed no settling or migration bias towards either mock-inoculated or infected plants. However, tomato VOC blends differed in light and darkness, suggesting aphids respond to a complex mix of olfactory, visual, and other cues influenced by infection. The LS-CMV strain induced no changes in aphid–plant interactions. Experiments using inter-strain recombinant and pseudorecombinant viruses showed that the Fny-CMV 2a and 2b proteins modified tomato interactions with Macrosiphum euphorbiae and Myzus persicae, respectively. The defence signal salicylic acid prevents excessive CMV-induced damage to tomato plants but is not involved in CMV-induced changes in aphid–plant interactions.

The worldwide invasive insect pest, Drosophila suzukii Matsumura (spotted-wing Drosophila), lays eggs in soft and stone fruit before harvest. Hatched larvae cause fruit collapse and significant economic losses. Current control methods rely primarily on foliar insecticide applications, which are not sustainable long-term solutions due to regulatory restrictions and the risk of insecticide resistance developing. We showed before that D. suzukii were deterred from laying eggs on artificial media previously visited by its sister species—Drosophila melanogaster. In the current study, laboratory choice test experiments were conducted to identify which D. melanogaster life stage (eggs, larvae, or adult) deterred D. suzukii oviposition. We demonstrated that the presence of live D. melanogaster larvae on the egg-laying media consistently deterred D. suzukii oviposition. Drosophila melanogaster cuticular hydrocarbons (CHCs) were examined as candidate for the oviposition deterrent. CHCs of larval and adult D. melanogaster and D. suzukii were analyzed. In both species, the composition of the CHCs of larvae was similar to that of adults, although quantities present were much lower. Furthermore, the CHC profiles of the two species were markedly different. However, when assayed as deterrents in the laboratory choice test experiment, CHC extracts from D. melanogaster did not deter oviposition by D. suzukii.