Laboratory Toxicity Profile of an Organic Formulation of Spinosad against the Eggplant Flea Beetle, Epitrix Fuscula Crotch

Paul Mcleod Tahir Rashid

doi:10.4172/2155-6202.1000103

Abstract

The eggplant flea beetle, Epitrix fuscula Crotch, is a major insect pest of eggplant, Solanum melongena L. var. esculentum (Solanaceae), produced in the south central United States and often requires management with insecticides immediately following setting of transplants into the field. Few insecticides approved for use in organic production have provided effective management of the beetles. The study reported herein demonstrates the effectiveness of Entrust, a new organic approved formulation of spinosad. Following exposure on eggplant foliage, Entrust was shown to be toxic to adult flea beetles with LC50 and LC95 values of 42.9 and 296.7 ppm, respectively. Although mortality following exposure was sometimes delayed until six days, the effects on flea beetle behavior were observed in as little as six hours following exposure. Feeding was significantly reduced one day after exposure to both the highest recommended field rate and to a 25% concentration of the high rate. Persistence in the field was short. No significant differences in mortality were detected for beetles transferred to treated and water-treated eggplant foliage taken three days after application. Of the insecticides approved for use in organic production, Entrust likely offers an excellent choice for management of eggplant flea beetles on eggplant.

Highlights

The eggplant flea beetle, Epitrix fuscula Crotch, is one of the major insect pests of eggplant, Solanum melongena L. var. esculentum (Solanaceae), produced in the south central United States
The spinosad formulation, Entrust, was toxic to eggplant flea beetle adults held on treated eggplant leaf disks
Many factors including spray coverage, persistence and insect behaviour may reduce the effectiveness of an insecticide applied under field conditions, the dosage-response data indicate that Entrust applied at the highest recommended field rate should be sufficiently toxic to effectively reduce eggplant flea beetle levels on eggplant

Summary

Introduction

The eggplant flea beetle, Epitrix fuscula Crotch, is one of the major insect pests of eggplant, Solanum melongena L. var. esculentum (Solanaceae), produced in the south central United States. The insect overwinters as an adult and attacks eggplant seedlings as soon as they are transplanted into the field in early spring. If beetle population level is high, injury can be severe and seedling death may occur This is especially common along field edges [2]. Ellis and Bradley [4] recommended several botanical insecticides for flea beetle management including neem, rotenone, pyrethrin and sabadilla Each of these materials may possess some toxicity to eggplant flea beetle, their benefits under field conditions are limited [5]. Adult numbers were reduced, damage levels were only reduced by about 50% despite four applications Another organic approved product, Nature’s Glory [citric acid], was tested by Sorensen and Cooke [7]. No other organically approved insecticide has been shown to provide acceptable management of the eggplant flea beetle

Methods

Results

Conclusion