Effect of different intercropping systems on tomato infestation with major insect pests; Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae), Myzus persicae Sulzer (Homoptera: Aphididae) and Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae).
Field-plot studies were carried out in Giza, Egypt, during 1988-90 to determine the effect of intercropping tomato with either onion or garlic on the level of infestation with Bemisia tabaci, Myzus persicae and Phthorimaea operculella. The numbers of adults of B. tabaci on tomato grown alone were higher than on either of the intercropping systems: infestation on tomato was reduced by 62-66% when grown with onion and by 69-70% when grown with garlic. During 1988-89, nymphal populations of M. persicae were significantly higher on tomato grown alone than when grown with either onion or garlic. During 1989-90, the number of nymphs on tomato grown alone, and on tomato grown with garlic were not significantly different but were significantly higher than on tomato grown with onion. Growing tomato with onion or garlic decreased the aphid population by 86-87% during 1988-89. During 1989-90, a population decrease of 8% was recorded on tomato grown with onion and 31% on tomato grown with garlic. Larval populations of P. operculella were significantly reduced by 80 and 91% on tomato intercropped with onion and garlic, resp., in 1988-89, but not in 1989-90. In both seasons studied, tomato yield was 114-207% and 104-284% higher in plants intercropped with onion and garlic, resp., compared to plots grown with tomato alone.