Use of Attractants to Suppress Oriental Fruit Fly and Cryptophlebia spp. in Litchi

Abstract

Litchi (Litchi chinensis Sonn.) is subject to damage by a range of insect pests, the most important of which are the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), the koa seedworm, Cryptophlebia illepida (Butler), and the litchi fruitmoth, C. ombrodelta (Lower) (also known as the macadamia nut borer) (Lepidoptera: Tortricidae). The activity of tephritid fruit flies and Cryptophlebia spp. (hereafter referred to as Cryptophlebia) both can lead to several types of fruit defects, including holes, stains, and release of fruit juices, making it difficult to distinguish which pest caused the damage. Field studies were conducted to minimize the occurrence of these types of fruit defects through use of a spinosad-based protein bait (GF-120 Fruit Fly Bait) to suppress oriental fruit fly populations, and an attractant associated with a contact insecticide (attract-and-kill) technique (Last Call) to suppress Cryptophlebia populations in litchi orchards at the scale of individual farms. The Last Call product used was based on a pheromone blend developed for the macadamia nut borer because preliminary tests identified that this blend was more attractive to both C. ombrodelta and C. illepida than was a pheromone blend developed for the oriental fruit moth, Grapholita molesta (Busck). Overall, based on results from four split plot litchi orchards, there was no significant difference in oriental fruit fly trap catch between spray and control sections at any trap service date. However, population reduction in the sprayed section of one orchard with a higher B. dorsalis population may have been a result of the spray application. Cryptophlebia trap catch was significantly lower in the treated orchards after the first Last Call application. Cryptophlebia infestation was more than three-fold greater than infestation by oriental fruit fly in each of the orchards. For both pests, there was no significant difference in infestation rate or infestation-related fruit damage between control and treatment orchards. Improved bait sprays and improved attract-and-kill products and/or larger treatment areas may be needed to provide satisfactory levels of fruit fly and Cryptophlebia suppression.