Detection and monitoring of resistance to the insecticide spinosad in the thrips Frankliniella occidentalis

Author(s)

Débora Soller Rais ^[1] ; Mário Eidi Sato ^[2] ; Marcos Zatti da Silva ^[3]

Affiliation

^[1] Instituto Biológico - Brasil

^[2] Instituto Biológico - Brasil

^[3] Instituto Biológico - Brasil

• Document type: Journal article
• Source: Bragantia; v. 72, n. 1, p. 35-40, 2013-05-10.

Abstract

The thrips Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is one of the major pests in greenhouses, especially on ornamental plants and vegetables. Among the problems faced by farmers are the difficulties in the control of this pest with the use of insecticides because of its preference for the inner parts of the flowers and the evolution of resistance to agrochemicals. The objective of this research was to characterize the spinosad resistance in F. occidentalis and to assess the frequency of resistant insects in commercial chrysanthemum fields from several counties in the state of São Paulo (SP). Selections for resistance to spinosad were performed under laboratory conditions, using a population of F. occidentalis collected in 2007 in a commercial chrysanthemum field in Campinas (SP). In the course of seven selections for resistance, the LC50 of spinosad increased from 8.41 mg a.i. L-1 to 1,111 mg a.i. L-1. Comparing the resistant (R) and the susceptible (S) strains, the resistance ratio (LC50 R / LC50 S) reached values up to 280-folds. A discriminating concentration of 98 mg a.i. L-1 was established for monitoring the spinosad resistance in F. occidentalis. The survey was conducted by collecting 19 populations of thrips in commercial chrysanthemum fields in the state of São Paulo. The bioassays were conducted with second ínstar nymphs of F. occidentalis, placed in bean leaf disc arenas. The spinosad was sprayed at the discriminating concentration on the nymphs of thrips, using a Potter spray tower. The results indicated high variability in the susceptibility to spinosad among F. occidentalis populations. Populations with up to 40.7% of resistant insects were found. This is the first report on spinosad resistance in F. occidentalis in Brazil. (AU)

• FAPESP's process: 12/17972-2 - Pesticide resistance in pests (Tetranychus urticae and Frankliniella occidentalis) and predators (Acari: Phytoseiidae) and management strategies for these pests
• Grantee: Mário Eidi Sato
• Support Opportunities: Regular Research Grants
• FAPESP's process: 07/08612-4 - Studies on pesticide resistance on thrips (Frankliniella occidentalis) and mites (Tetranychus urticae), in several crops, and host preference of these pests on ornamental plants in the State of São Paulo
• Grantee: Mário Eidi Sato
• Support Opportunities: Regular Research Grants