Abundance of adventive thrips palmi (Thysanoptera: Thripidae) populations in Florida during the first sixteen years

Abstract

Thrips palmi Karny (Thysanoptera: Thripidae), invaded Miami Dade-county in 1990 and caused significant economic damage by defoliating various vegetable crops. It commonly occurs on the abaxial surface of host leaves where eggs are deposited individually inside the leaf tissues. Highest abundance of T. palmi was recorded on bean and eggplant in 1991-1994 in Tropical Research and Education Center research plots and commercial fields in MiamiDade County. Density of T. palmi decreased significantly in subsequent years after the use of spinosad and other effective chemical insecticides. Thrips palmi populations increased in 2008 in spite of use of spinosad and showed increasing pattern causing crops loss at economic level. Orius insidiosus Say population was low in both TREC research fields and commercial fields due to harsh chemical management program, where insecticides belonging to various chemical classes were used alone (TREC fields) or in combination (commercial fields) to control T. palmi and other insect pests. None of the commonly used available insecticides alone or in combination provided satisfactory control of T. palmi in the early stage of invasion. Amongst various insecticides tested spinosad provided significant control of T. palmi on the crops until 2008 after which there was reduced effect of the chemical due to frequent use for managing multiple pests.