Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Eggplant Insect Pests• Mulching has potential in reducing thrips damage. White-plastic or silvery plastic mulch can reducethrips infestation considerably. See box below. However, these mulching materials are expensive.Straw mulch can also be used. Colored paper or colored plastic sheets attract thrips.Reflecting mulches to prevent aphid and thrips infestation?!?In countries like U.S.A. (California), some farmers place aluminium film on the soil around and amongplants. The reflection of (sun)light deters aphids and thrips and they will not land in the crop but flyelsewhere. For the best prevention, 50% of the soil should be covered with the reflecting mulch.The repellency could be associated with disturbance of orientation before landing on the crop. In caseof thrips, another possibility is the reduced access to suitable pupation sites in the soil under the crop(Vos, 1994).• Flooding the field seems to have potential in reducing thrips populations, presumably drowning thripspupae in the soil. This may be feasible in areas where vegetables are rotated with rice. Anotheroption is to flood the field during the dry season for irrigation. When the field is flooded for longerperiod of time, pupae in the soil may be killed. More research is needed.• Intercropping: there are no consistent effects reported on thrips populations. Not advisable.• To reduce thrips infestations at seedling stage, which reduces plant vigor later on, seedlings could beraised inside a fine-mesh net cover, fine enough to exclude thrips. However, this type of screen isextremely expensive. It is only justified when problems with thrips (or thrips transmitted diseases) aresevere.• Excessive use of fertilizer which increases vegetative growth beyond the normal needs of the plantshould be discouraged. Excessive growth does not increase yield but it does provide shelter forthrips.• Avoid unnecessary applications of pesticides to prevent secondary outbreaks of thrips.Once thrips are present in the field:• When numbers are low, and symptoms of plant injury are not severe, no control measures need to betaken. Continue monitoring population growth and check for parasitoid presence.Points to remember about thrips:1. Thrips have probably become an important pest as a result of increased use of pesticides whichkilled the natural enemies of thrips.2. Thrips have several natural enemies, e.g. predatory mite species, predatory bugs, andlacewings.3. Cultural practices that help prevent/delay crop infestation include flooding the field, and use ofsilvery plastic mulch.4. Avoid unnecessary pesticide applications to prevent secondary thrips outbreaks.Related exercises from CABI Bioscience/FAO Vegetable IPM Exercise Manual4-D.4. Thrips feeding symptom development89Eggplant Ecological Guide