Optimizing Western Flower Thrips Management on French Beans by Combined Use of Beneficials and Imidacloprid

Abstract

Western flower thrips (WFT), Frankliniella occidentalis (Pergande), is an important pest of vegetable crops worldwide and has developed resistance to many insecticides. The predatory mites Neoseiulus (=Amblyseius) cucumeris (Oudemans), the entomopathogenic fungus Metarhizium anisopliae (Metsch.), and an insecticide (imidacloprid) were tested for their efficacy to reduce WFT population density and damage to French bean (Phaseolus vulgaris L.) pods under field conditions in two planting periods. Metarhizium anisopliae was applied as a foliar spray weekly at a rate of one litre spray volume per plot while imidacloprid was applied as a soil drench every two weeks at a rate of two litres of a mixture of water and imidacloprid per m2. Neoseiulus cucumeris was released every two weeks on plant foliage at a rate of three mites per plant. Single and combined treatment applications reduced WFT population density by at least three times and WFT damage to French bean pods by at least 1.7 times compared with untreated plots. The benefit-cost ratios in management of WFT were profitable with highest returns realized on imidacloprid treated plots. The results indicate that M. anisopliae, N. cucumeris, and imidacloprid have the potential for use in developing an integrated pest management program against WFT on French beans.

Effectiveness and profitability of insecticide formulations used for managing snap bean pests

“…Thus in our study, the pest might have appeared when the Imidacloprid had become in effective. Nyasani et al (2015), however, applied Imidacloprid three times at 14d interval, starting at budding. This targeted the stage when the thrips were most abundant.…”

Establishment of polyethylene‐glycol‐mediated protoplast transformation for Lecanicillium lecanii and development of virulence‐enhanced strains against Aphis gossypii

“…From then on, intensive efforts began to enhance fungal efficacy against pest insects by transferring endogenous or exogenous pathogenic genes, 12 e.g. cuticle-degrading protease gene, 11 chitinase gene, 13,14 fusion genes of protease/chitinase, 15,16 hybrid genes of chitinase/chitinase, 17 DHN-melanin biosynthesis 3 and scorpion toxin genes, 18 -20 etc. Lecanicillium lecanii, an important entomopathogenic fungus, is capable of infecting pest insects, has a broad geographical distribution and shows promise in commercial development. 21 Knowledge of the mechanism used by L. lecanii to infect insect pests and understanding of specific host/pathogen interaction are necessary for virulence improvement of L. lecanii through genetic modification.…”

“…Entomopathogenic fungi play a crucial role in controlling insect pests in nature and are being utilised as supplements or alternatives to chemical insecticides . However, in spite of intensive efforts, entomopathogenic fungi have not fulfilled expectations as mycoinsecticides in their commercialisation and large‐scale application because of relatively slow kill compared with chemical pesticides and a requirement for high amounts of inocula .…”

“…From then on, intensive efforts began to enhance fungal efficacy against pest insects by transferring endogenous or exogenous pathogenic genes, e.g. cuticle‐degrading protease gene, chitinase gene, fusion genes of protease/chitinase, hybrid genes of chitinase/chitinase, DHN‐melanin biosynthesis and scorpion toxin genes, etc.…”

Genetic structure and diversity of western flower thrips, Frankliniella occidentalis in a French bean agroecosystem of Kenya

“…So far, farmers mostly use synthetic insecticides to control this pest, but due to issues such as stringent regulations on the export market and development of insecticide resistance (Brødsgaard, 1994;Nderitu et al, 2008), * E-mail: hondelmann@ipp.uni-hannover.de new control strategies need to be developed. Recent approaches to manage F. occidentalis in Kenya include improved monitoring techniques (Muvea et al, 2014), intercropping (Nyasani et al, 2012), integration of Metarhizium-based products with kairomones (Niassy et al, 2012a(Niassy et al, , 2012bMfuti et al, 2016) and predatory mites (Nyasani et al, 2015). However, little is known about field ecology and population genetics of F. occidentalis in Kenya, including host preferences, adaptation potential and genetic variation on local and regional scales, thus constraining development and implementation of new control approaches.…”