High throughput sequencing reveals Drosophila suzukii responses to insecticides

Abstract

Global climate change and acquired resistance to insecticides are threats to world food security. Drosophila suzukii, a devastating invasive pest in many parts of the world, causes substantial economic losses to fruit production industries, forcing farmers to apply broad-spectrum insecticides frequently. This could lead to the development of insecticide resistance. We determined the Lethal Concentration 50 (median lethal concentration, LC ) values of zeta-cypermethrin, spinosad, and malathion insecticides against D. suzukii colonies established from Clarke and Pierce county Georgia, United States. The LC values were 3 fold higher in the Pierce county population for all insecticide treatments. We then used RNA sequencing to analyze the responses of Pierce and Clarke population flies surviving a LC treatment of the 3 insecticides. We identified a high number of differentially expressed genes that are likely involved in detoxification and reduced cuticular penetration, especially in the Pierce population, with extensive overlap in differentially expressed genes between the 3 insecticide treatments. Finally, we predicted fewer nonsynonymous single nucleotide variants having deleterious effects on protein function among detoxification, insecticide target, and cuticular protein encoding genes in Pierce flies. Thus a combination of increased gene expression and fewer deleterious single nucleotide variants highlights molecular mechanisms underlying the higher LC values for Pierce population flies.

Identification and risk assessment of spinosad resistance in a California population of Drosophila suzukii

“…However, elevated survival at these concentrations is not sufficient for confirming resistance; instead, full dose–response analyses are needed to generate and compare lethal concentration values of susceptible and putatively resistant field populations. Recently, D. suzukii from several locations in the USA were tested using this approach, but no resistant populations have been identified to date . In one study, decreased susceptibility to spinosad, malathion and zeta‐cypermethrin was detected for D. suzukii from commercial blueberry plots in Georgia when compared to a susceptible laboratory colony, but these changes were relatively small (i.e., ∼3‐fold for each insecticide) .…”

“…Recently, D. suzukii from several locations in the USA were tested using this approach, but no resistant populations have been identified to date . In one study, decreased susceptibility to spinosad, malathion and zeta‐cypermethrin was detected for D. suzukii from commercial blueberry plots in Georgia when compared to a susceptible laboratory colony, but these changes were relatively small (i.e., ∼3‐fold for each insecticide) . An additional attempt to select for insecticide resistance in the laboratory using flies from British Columbia, Canada was also unsuccessful …”

Development of a rapid assessment method for detecting insecticide resistance in spotted wing Drosophila (Drosophila suzukii Matsumura)

“…Repeated applications of insecticide sprays in commercial fruit fields each year have raised concerns about the potential for the development of resistance in D. suzukii populations, and research on this topic should be a priority . However, surveys of D. suzukii populations to assess their susceptibility to insecticides have so far been limited . Hamby et al investigated the toxicity of malathion and fenpropathrin to D. suzukii at different times of day and under different day length and temperature regimes.…”

Phenotypic and transcriptomic responses to stress differ according to population geography in an invasive species

“…This set of common DE genes likely corresponded to those directly implicated in stress response. In agreement with this idea, we founded genes such as Hsp or genes of the cytochrome gene family[49][50][51][52][53][54].At the transcriptomic level, the Japanese genotype appeared dissimilar from the other two. First, as discussed above, the transcriptional response to paraquat involved a much smaller portion of the genome and there were fewer DE genes unique to this genotype.…”