Field application of entomopathogenic nematodes against Thaumatotibia leucotreta in South African avocado, litchi and macadamia orchards

摘要

False codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), is an important pest of fruit trees in South Africa. The subtropical fruit tree crop industries use a combination of techniques for T. leucotreta suppression. Semi-field trials were conducted in avocado, litchi and macadamia orchards, using four entomopathogenic nematode (EPN) species. The effect on T. leucotreta mortality, directly after application (twodays), as well as on persistence for 7, 14, 21, 28, 35, and 42days post-application, was determined. Results from the field trials, using 30 IJscm(2) of Steinernema yirgalemense, showed the highest mortality of 86% directly after application, with Steinernema litchii being the least effective of the four EPN species, with 63% mortality. High persistence was found until day 14, with a steep decline thereafter until day 28. Local South African EPN species showed great potential for the future control of the late instar T. leucotreta, with the added advantage of persistence.