Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Eggplant Insect PestsSpraying insecticides resulting in MORE whiteflies??!!There is a possibility that treating a resistant whitefly population with certain insecticides couldactually accelerate population growth. This could be because more eggs are laid when the insect isunder biochemical stress, or because natural enemies are eliminated.To minimize this potential problem, insecticide applications should be used as little as possible,judiciously and combined with non-chemical control tactics (ref. www25).Once whiteflies are present in the field:• Chemical control of whiteflies is both expensive and increasingly difficult.Many systemic and contact insecticides have been tested for control ofwhiteflies, but few give effective control. Besides the cost of treatment,other factors involved in chemical control decisions are:• the need for thorough coverage: whiteflies are located on theundersides of leaves where they are protected from overheadapplications, and the immature stages (except for the first one) areimmobile and do not increase their exposure to insecticides bymoving around the plant,• the risk of secondary pest outbreaks (due to elimination of natural enemies),• the risk of whiteflies developing insecticide resistance (a very serious threat!), and• the regulatory restrictions on the use of insecticides.Points to remember about whitefly:1. Whitefly is usually not a major pest in eggplant.2. Whitefly has many natural enemies which can keep populations low.3. Avoid unnecessary application of pesticides to prevent secondary outbreak of whiteflies due toelimination of natural enemies. Treating pesticide-resistant whitefly populations in addition, canaccelerate population growth.4. Fungal biocontrol products, where available, may offer good whitefly control under certainconditions.Related exercises from CABI Bioscience/FAO Vegetable IPM Exercise Manual4-D.1 Predation of sucking insects in insect zoo4-D.7 Parasitism of whitefly3-F.2 Raise seedlings in a screen cage3-F.3 Application of light reflective mulch in field to manage virus incidence3-F.5 Effect of sanitation on spread of virusFor more background reading and practical exercises on whiteflies, please refer to the report of CABIBioscience: “Whitefly ecology exercises – CABI Whitefly workshop, KL, Malaysia, Sept 2000”. Seereference list (chapter 11) on how to obtain copies.5.9 Red ant - Dorylus orientalisCommon name: Oriental army ant.There are many species of ants. Some species have found to be good predators of pest insects, forexample weavers ants (Oecophylla sp.).Many predatory ants also collect honeydew (the excretion of e.g. aphids). These species often interferewith biological control measures because they may protect the aphid colony from other intruders thatwant to attend the aphids. The ants thus often reduce the effectiveness of other aphid predators andparasitoids.94Eggplant Ecological Guide