Insecticide resistance and fitness cost in Bemisia tabaci (Hemiptera: Aleyrodidae) invasive and resident species in La Réunion Island

Abstract

BACKGROUND Global and intensive use of insecticides has led to the emergence and rapid evolution of resistance in the major pest Bemisia tabaci (Gennadius). In La Réunion, an island of the South West Indian Ocean, three whitefly species coexist, two of which are predominant, the indigenous Indian Ocean (IO) and the invasive Middle East Asia Minor 1 (MEAM1) species. To assess the resistance level of both of these species to acetamiprid and pymetrozine, whitefly populations were sampled at 15 collection sites located all over the island in agroecosystems and natural areas, and tested using leaf‐dip bioassays. We also investigated the potential cost of resistance to acetamiprid by measuring six fitness‐related traits for MEAM1 populations that displayed different resistance levels. RESULTS IO was mainly found in natural areas and was susceptible to both acetamiprid and pymetrozine. MEAM1 populations displayed evidence of high resistance to pymetrozine, whereas resistance to acetamiprid was more variable. No fitness‐related costs were associated with this resistance in MEAM1 populations. CONCLUSION This is the first assessment of the susceptibility to insecticides for B. tabaci IO species. For the time being, no resistance to the tested insecticides has evolved in this species despite (i) its presence in agroecosystems and their surroundings, and (ii) its close proximity to, and possible hybridization with, the MEAM1 species. In contrast, with continuous selection pressure of insecticide treatments and in the absence of fitness cost to resistance, the invasive exotic species MEAM1 will continue to threaten agriculture in La Réunion. © 2019 Society of Chemical Industry

Distribution of invasive versus native whitefly species and their pyrethroid knock-down resistance allele in a context of interspecific hybridization

“…Genotyping and sequencing of the kdr mutation indicates that the MED species in La Réunion is as well armed against pyrethroids as MEAM1, but this species may lack other resistance mechanisms in those particular populations. Unfortunately, because of the low occurrence of the MED species in La Réunion, insecticide resistance could not be assessed using bioassays so far 51 .…”

Perspective: common errors in dose–response analysis and how to avoid them

“…The relative potency of three insecticides (lufenuron, teflubenzuron and novaluron) on Chrysoperla externa (green lacewing) was estimated to be between 0.5 and 15, but no SEs were reported for these values 30 . A high RI to pymetrozine insecticide was reported for several populations of Bemisia tabaci (whitefly) without SEs and post hoc analysis 31 . Sometimes a population is classified as a highly resistant accession simply because of a high RI.…”

“…30 A high RI to pymetrozine insecticide was reported for several populations of Bemisia tabaci (whitefly) without SEs and post hoc analysis. 31 Sometimes a population is classified as a highly resistant accession simply because of a high RI. To illustrate this point, dose-response curves were fitted simultaneously to a hypothetical dataset.…”

Characterization of Field-Evolved Resistance to Afidopyropen, a Novel Insecticidal Toxin Developed from Microbial Secondary Metabolites, in Bemisia tabaci

“…Further studies on the cross-resistance patterns, synergistic effects, and fitness costs of field-developed resistance to chemical agents in insect pests could contribute to the development of strategies for delaying the evolution of resistance [ 18 ]. Although a series of publications have been reported on cross-resistance patterns, synergistic effects, and fitness costs of popular chemical agents in whiteflies, there is a lack of published data about whitefly resistance to afidopyropen [ 19 , 20 , 21 , 22 , 23 ]. In this study, after performing reversions and selections with a field-collected afidopyropen-resistant HD population, one strain with a high level of afidopyropen resistance, HD-Afi, and one resistance-reversed strain, HD, were obtained.…”