Acute effect of low-dose thiacloprid exposure synergised by tebuconazole in a parasitoid wasp

Abstract

Agricultural practices often involve tank-mixing and co-application of insecticides with fungicides to control crop pests. However, natural methods relying on biological control agents such as hymenopteran parasitoids have been shown to be highly effective in suppressing crop pest populations. The current body of insecticide risk assessment data accounting for fungicide co-application is very small, the present study being the first to examine this in a parasitoid wasp. Through low-dose exposure to dry residues of the neonicotinoid insecticide thiacloprid, we examined its mortal and knockdown effect on Aphelinus abdominalis when co-applied with increasing doses of the fungicide tebuconazole. Both of these acute effects of thiacloprid were synergised (toxicity increased to a greater-than-additive effect) by tebuconazole, resulting in significant mortality from low-dose co-applications of tebuconazole, and significant knockdown even without co-applied tebuconazole, the effect increasing as tebuconazole concentration increased. We show the highly toxic effect that a low dose of thiacloprid imposes on A . abdominalis populations, and a synergistic toxicity when co-applied with low doses of tebuconazole. Our work suggests a need for updating pesticide risk assessment methods, accounting for pesticide mixtures, in order to make these risk assessments more field relevant.

Compatibility of early natural enemy introductions in commercial pepper and tomato greenhouses with repeated pesticide applications

“…(Biobest, 2019) and other NE in semifield and field (Sterk et al, 1999). Besides, the fungicide seemed not to have synergized effects with any of our pesticides despite they are reported with neonicotinoid thiacloprid (Willow et al, 2019).…”

Targeting a coatomer protein complex-I gene via RNA interference results in effective lethality in the pollen beetle Brassicogethes aeneus

“…Consequently, B. aeneus has developed high levels of resistance to pyrethroid insecticides in several areas across Europe (Slater et al 2011;Heimbach and Müller 2013;Zamojska 2017;Stará and Kocourek 2018;Kaiser et al 2018). While neonicotinoid insecticides are also being applied in B. aeneus management (Seidenglanz et al 2017;Kaiser et al 2018), exposure to neonicotinoids has shown negative effects on a wide range of nontarget organisms (Gibbons et al 2015;Pisa et al 2017;Willow et al 2019;Berheim et al 2019;Calvo-Agudo et al 2019;Wu et al 2019). For example, in oilseed rape agroecosystems, nontarget organisms negatively affected by thiacloprid applications could include economically important parasitoids of B. aeneus, given that laboratory studies have demonstrated the detrimental effect of thiacloprid on other parasitoid wasps (Sugiyama et al 2011;Jans 2012;Willow et al 2019).…”

“…While neonicotinoid insecticides are also being applied in B. aeneus management (Seidenglanz et al 2017;Kaiser et al 2018), exposure to neonicotinoids has shown negative effects on a wide range of nontarget organisms (Gibbons et al 2015;Pisa et al 2017;Willow et al 2019;Berheim et al 2019;Calvo-Agudo et al 2019;Wu et al 2019). For example, in oilseed rape agroecosystems, nontarget organisms negatively affected by thiacloprid applications could include economically important parasitoids of B. aeneus, given that laboratory studies have demonstrated the detrimental effect of thiacloprid on other parasitoid wasps (Sugiyama et al 2011;Jans 2012;Willow et al 2019). Notably, among a European Union (EU)-wide ban on the outdoor use of three other neonicotinoids, thiacloprid is currently banned from both outdoor and greenhouse use in France, with an EU-wide ban on the outdoor use of thiacloprid tentative for implementation by 3 August 2020, with maximum grace period up to 3 February 2021 (European Commission 2018), based on the European Food Safety Authority's (EFSA) peer review of the risk assessment of thiacloprid (Abdourahime et al 2019).…”

Social, Psychological and Health Impact of Coronavirus Disease (COVID-19) on the Elderly: South African and Italian Perspectives

“…-Paleolog et al (2020) showed the effects of imidacloprid may affect proteolysis, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and global DNA methylation in honeybees. -Willow et al (2019) provide further evidence of the significance of synergistic effects between neonicotinoids and fungicide when co-applied. The general reinforcing effect from multiple stressors also features in Wade et al (2019).…”