SUSTAINABLE MANAGEMENT OF KEY LEPIDOPTERAN INSECT PESTS OF VEGETABLES

Abstract

Insect pests are the main limiting factor for vegetable production in India and tropical Asia, amongst which Lepidopteran pests cause a significant amount of damage. Vegetables are some of the most profitable crops and farmers everywhere feel the need to protect such high value crops from any type of damage caused by insect pests. They often use synthetic insecticides indiscriminately, and insect resistance to insecticides is very common. Lepidopteran pests such as diamond-back moth (DBM) on cabbage (Plutella xylostella), fruit borer on tomato (Helicoverpa armigera), pod borer on chilli (Spodoptera litura), shoot and fruit borers on brinjal (Leucinodes orbonalis) and okra (Earias fabia) are among the major pests of vegetables. To control Lepidopteran pests efficiently, some new pesticides, with novel modes of action, have been developed recently. To determine the effectiveness of the new pesticides compared with traditional chemicals (chlorpyrifos+cypermethrin), five field experiments were done on brinjal, okra tomato, cabbage and chilli, over two seasons. Altogether nine pesticides (flubendiamide, spinosad, emamectin benzoate, chlorfenapyr, Bacillus thuringiensis, novaluron, lufenuron, methoxyfenozide and mixed formulations of chlorpyrifos+cypermethrin) were used with untreated controls. All other agronomic practices were standard, and a blanket spray to control sucking pest insects and mites was applied when necessary. Results showed that flubendiamide, spinosad and chlorfenapyr were highly effective in reducing the damage caused by diamond-back moth on cabbage, fruit borer on tomato, pod borer on chilli, shoot and fruit borer on brinjal and shoot and fruit borer on okra, and led to increases in yield. Novaluron was most effective against pod borer on chilli, closely followed by spinosad, flubendiamide and chlorfenapyr. In the case of fruit borer on tomato, spinosad was the most effective. Shoot and fruit borers on brinjal and okra were also controlled effectively by flubendiamide, spinosad and chlorfenapyr. Emamectin benzoate methoxyfenozide, and Bacillus thuringiensis, also performed well in reducing damage and increasing yield. Bacillus thuringiensis and methoxyfenozide were, however, less effective against shoot and fruit borer on brinjal and okra. The new pesticides, with novel modes of action and high selectivity, were highly effective against Lepidopteran pests. They are safer to non-target organisms and quickly degrade to non-toxic products.