Influence of Intercropping Vegetable Crops on the Population of Some Arthropods Associated with Eggplant (Solanum melongena L.) and Damage Potential of Eggplant Fruit and Shoot Borer (Leucinodes orbonalis Guenee) in the Presence of Radish (Raphanus sativu
The effects of plant community diversity on the population dynamics of some major insect pests of eggplant were studied in mixed and monocultures of eggplant (Solanum melongena L.) intercropped with bush sitao (Vigna unguiculata ,x Vigna unguiculata var. sesquipedalis), mungbean [Vigna radiata (L.) R. Wilcz.] and radish (Raphanus sativus L.). Significant differences were observed in the 10-wk total count for the eggplant fruit and shoot borer (EFSB), Leucinodes orbonalis Guenee. The lowest count of EFSB population in the three intercrops was registered in eggplant-radish intercrop at 9–11 wk after transplanting.
Damage potentials and host-finding behavior of EFSB in the presence of eggplant and radish were investigated in the laboratory using choice and no-choice cage bioassays. At a ratio of 1:4 eggplant-radish, a significant decrease was observed in the number of moths alighting on eggplant (0.50) when compared with those alighting on eggplant alone (1.96) at 24 h after introduction. The average percent shoot damage per plant for the 1:4 eggplant-radish mixture ratio was significantly lower (8.4%) than for eggplant alone (16.2%). Our experiments indicate reduced presence of EFSB on eggplant and reduced eggplant shoot damage in the presence of radish.
Key Words: beneficial arthropods, habitat manipulation, oviposition, polyculture, natural enemies, vegetational diversity