Genetics of Spinosad Resistance in Frankliniella occidentalis (Thysanoptera: Thripidae)

Abstract

The genetic basis of spinosad resistance was investigated in the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). The resistant strain, selected in the laboratory for spinosad resistance from a pool of thrips populations collected in Almeria (southeastern Spain), showed a very high resistance to spinosad (356,547-fold based on LC50 values) compared with the laboratory susceptible strain. Mortality data from reciprocal crosses of resistant and susceptible thrips indicated that resistance was autosomal and not influenced by maternal effects. Analysis of probit lines from the parental strains and reciprocal crosses showed that resistance was expressed as an almost completely recessive trait. To determine the number of genes involved, a direct test of monogenic inheritance based on the backcrosses suggested that resistance to spinosad was probably controlled by one locus. Another approach, which was based on phenotypic variances, showed that nE, or the minimum number of freely segregating genetic factors for the resistant strain, equaled 0.59.

Transcripts of the nicotinic acetylcholine receptor subunit gene Pxylα6 with premature stop codons are associated with spinosad resistance in diamondback moth, Plutella xylostella

“…Therefore, we should be cautious of extrapolating truncated transcripts of a6 as a resistance mechanism to other species. It will be interesting to elucidate the expression of a6 orthologs in spinosad-resistant tobacco budworm (Wyss et al 2003) and western flower thrips (Bielza et al 2007) in order to determine whether misspliced a6 is the spinosad resistance mechanism in these species. Fig.…”

The biology of insecticidal activity and resistance

“…The only mitigating factor is that these resistances are largely recessive which, in a field setting, would slow their increase in frequency. Recessive resistances to spinosyn and neonicotinoids due to target insensitivity have been observed in several pest insect species (Bielza et al, 2007;Shono and Scott, 2003;Wang et al, 2009;Wyss et al, 2003). To date the only characterised cases are the truncated Pxa6 conferring resistance to spinosyn in P. xylostella (Baxter et al, 2010) and the neonicotinoid resistant, ligand binding region substitutions in N. lugens (Liu et al, 2005).…”

Comparison of two methods of monitoring thrips populations in a greenhouse rose crop

“…Thrips cause considerable damage to commercial flower crops, through direct feeding on marketable produce (i.e., flowers or flower buds) or as occasional vectors of plant pathogens (Brodsgaard 2004;Jones 2005). There are major problems associated with usage of insecticides: resistant strains are appearing (Esponisa et al 2002;Humeres and Morse 2006;Bielza et al 2007), and it is now well known that they have considerable impacts on human health and non-target organisms (Weisenburger 1993;Desneux et al 2007). Theses concerns are leading to legal restrictions on the insecticides allowed.…”