Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________Major Natural Enemies of Eggplant Insect Pestsrelease of nematodessearch for new hostsreproductionnematodes enter the insectrelease of bacterial cellshost diesmatingLife cycle of insect-killing nematodes(modified from Hoffmann, 1993)EffectivenessInsect-attacking nematodes are best suited for use against pest insects that spend some or most of theirlife cycle in the soil or in moist, protected places (like inside shoots and fruits). However, nematodes areoften not effective against insects feeding on open foliage because they quickly lose effectiveness in dryconditions. They require moisture to travel. Nematodes can travel in the soil over considerable distancesand actively seek their prey if temperature and humidity are correct.Nematode movement through the soilAs with most biological control agents, to use insect-pathogenic nematodes effectively, it is alsonecessary to understand the life-cycle of the pest insect to ensure that the most susceptible life stage istargeted. Many vegetable insect pests are susceptible to attack by nematodes but for many, the potentialof nematodes for field control still needs to be evaluated.Nematodes can be cultured in living hosts and in artificial media with little chance for contamination.Several species of nematodes are now commercially available. See “The Biopesticide Manual” andinternet sites such as www14 and www15 (chapter 11, Reference list).Nematode solutions, when obtained from elsewhere, can be stored in the refrigerator for a short timeafter arrival because the nematodes are in a dormant state. Before applying the nematodes, thisdormancy must be broken by stirring them in room temperature (over 18 o C) water to provide oxygen.After dormancy is broken, the nematode-solution must be used immediately. They prefer a moist soil andare damaged by light and so should be applied in the evening. Beneficial nematodes move faster insandy soil than clay.ConservationGuidelines for conserving native entomopathogenic nematodes have not been well documented. Ingeneral, nematodes (both when indigenous and when applied as a spray) need protection from thedrying radiation of the sun and from extremes of temperature. Although they need a moist environment tostay alive and move around, they can form a “resting stage” to survive adverse conditions.115Eggplant Ecological Guide