Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Eggplant Insect PestsNatural enemies• Predatory mite Phytoseiulus persimilis. An orange-red mite, about 1 mm long. This mite cannot fly butmoves around much quicker than the spider mites. In India, this predatory mite has proved to beeffective against spider mite in okra. Also in many European countries and in the USA, this predatorymite can be bought from specialized shops for release in greenhouses or in the field. Results ingreenhouses are very good and hardly any chemical pesticides need to be applied for spider mitecontrol. Phytoseiulus needs high humidity for effective mite control.• The predatory mite Amblyseius tetranychivorus, indigenous in India, was also found effective againstspider mite in okra. This predatory mite is commercially available in some western countries. It isreleased on fairly large scale for spider mite control in many vegetable crops including eggplant,strawberry, and gourds in China. Numerous research findings are available on how to mass-produceand conserve predatory mites.• The gall-midge Feltiella acarisuga. This is again a commercially available natural enemy of spidermite. It is very successful in European countries. The adult midge is about 2 mm long, pink-brown,with long legs. Feltiella acarisuga is often used in greenhouses together with the predatory mitePhytoseiulus persimilis, especially in periods with low humidity levels (which hinder the developmentof Phytoseiulus). The gall-midge Feltiella acarisuga can fly, which makes it more mobile thanPhytoseiulus persimilis. High humidity boosts the emergence of gall-midges.• The predatory bug Macrolophus caliginosus is a known predator of spider mites. Its main host iswhitefly and to a lesser extent aphids, moth eggs, leaf-miner larvae and thrips. Bug populationsdevelop most rapidly on whitefly. Adult bugs can also survive for some time on plant saps.Macrolophus is another commercially available natural enemy, again successful when released ingreenhouse environments. Whether this bug occurs naturally in the tropics and how effective it is inspider mite control needs to be further investigated.• Larvae of the green lacewing Chrysopa sp. are predators of spider mite.• Ladybeetle adults and larvae feed on spider mites.How effective one predator is, how many prey it eats per day, usually depends on many factors includinghost plant and temperature. The eating-capacity of a predator can easily be tested in the field with acaged plant or in an insect zoo (glass or plastic jar). See section 4.8.Circle of life: mites and predatory mite reproduction examplesIn a study from China, 50 red mites inoculated on eggplant cultivated in plastic bags multiplied to13,000-14,000 individuals after 40 days, and the predatory mite Amblyseius longispinosus placedinto the bag could subsequently propagate to 500-1,000 individuals after 20-25 days. Not bad…!(Zhang-YanXuan, 1996).Management and control practicesPrevention activities:• In general, vigorous growing plants are less susceptible to pest and disease attack. Creating properenvironment, e.g. applying lots of compost to improve the soil structure, applying modest rates ofnitrogen, help preventing mite infestation.• Predatory mites can often be found spontaneously in the field. Like many other predators, thesepredatory mites are very sensitive to pesticides, especially broad-spectrum pesticides. Avoid the useof such pesticides as much as possible.Once spider mites are present in the field:• Small populations can be tolerated because they allow build-up of natural predatory mite populations.• Mites do not like a wet environment. Plants infested by mites can be hand sprayed with water. Part ofthe mites will be washed off and population growth will be slowed down. Only applicable at smallerareas or when few plants are infested.80Eggplant Ecological Guide