Sustainable biological control strategies for growers of greenhouse cucumber in Lebanon.

Abstract

Greenhouse farmers in Lebanon rely heavily on pesticide use for pest management.At present, they do not have access to biological control methods to control pests that threaten agricultural crops. Moreover, few if any field studies were conducted to assess the control efficacy of Amblesius swirskii, Aphidius colemani , Eretmocerus eremicusand Phytoseilus persimilis for the management of greenhouse cucumber arthropod pests in Lebanon. To test the efficacy of natural enemies, four trials were conducted at two different locations, one in Byblos and the other in Zahrani.The first three trials were done without having a control greenhouse. The fourth trial included a control greenhouse (GH) where the farmer followed his normal plant protection practices while in the other GH, IPM practices were implemented including natural enemy releases. Weekly monitoring of whitefly (WF),aphid, thrips and mitepopulations on cucumber leaves and-or flowers were conducted and data were recorded. Trial 1 conducted in Byblos during the fall and winter season showed very promising results. Only one release ofAmblesius swirskiiand Phytoseilus persimiliswas enough to keep the population of major insect pests at relatively low populations during most of the growing season. No single insecticide spray was used.The results of trials 2 and 3 conducted in Zahrani were less promising due to two main reasons. First, the experimental variety planted was very susceptible to downy mildew and the location was close to the sea with a RH thatremained high, between 80-90percent during the growing season which forced the farmer to apply fungicide sprays at weekly intervals. Second, the close proximity of the greenhouses to a neglected eggplant open field, which acted as a source of insect and mite pests mainly whiteflies.As for trial 4 which was duringthe spring cropping season, the predatory miteA.swirskii successfully maintained the thrips and whitefly populations at a low level similar to that obtained by the farmer who used six pesticide sprays with a mix