Integrated pest management for eggplant fruit and shoot borer (Leucinodes orbonalis) in South and Southeast Asia: past, present and future

The integrated pest management (IPM) strategy for the control of eggplant fruit and shoot borer (EFSB) consists of resistant cultivars, sex pheromone, cultural, mechanical and biological control methods. Eggplant accessions EG058, BL009, ISD006 and a commercial hybrid, Turbo possess appreciable levels of resistance to EFSB. Use of EFSB sex pheromone traps based on (E)-11-hexadecenyl acetate and (E)-11-hexadecen-1-ol to continuously trap the adult males significantly reduced the pest damage on eggplant in South Asia. In addition, prompt destruction of pest damaged eggplant shoots and fruits at regular intervals, and withholding of pesticide use to allow proliferation of local natural enemies especially the parasitoid, Trathala flavo-orbitalis reduced the EFSB population. The IPM strategy was implemented in farmers’ fields via pilot project demonstrations in selected areas of Bangladesh and India and its use was promoted in both countries. The profit margins and production area significantly increased whereas pesticide use and labor requirement decreased for those farmers who adopted this IPM technology. The efforts to expand the EFSB IPM technology to other regions of South and Southeast Asia are underway. INTRODUCTION Eggplant (Solanum melongena) is one of the most important vegetables in South and South-East Asia. It is grown on over 678,000 ha, which is about 37% of the world eggplant area, with a production of 10.50 million t (FAO, 2007). Eggplant fruit and shoot borer (EFSB), Leucinodes orbonalis Guenée (Lepidoptera: Pyrallidae) is one of the most destructive pests on eggplant in South and Southeast Asia. Larvae of this insect bore inside plant shoots and fruits adversely affecting plant growth, yield and fruit quality, and thus making it unfit for human consumption. The yield reduction could be as high as 70% (Islam and Karim, 1991; Dhandapani et al., 2003). Hence, the farmers in the region rely exclusively on the application of chemical insecticides to combat EFSB which has resulted in a tremendous misuse of pesticides in an attempt to produce damage-free marketable fruits. Survey of pesticide use in Bangladesh indicated that farmers spray up to 180 times with chemical insecticides during a year to protect their eggplant crop against EFSB (SUSVEGAsia, 2007). The pesticide use is equally intensive in the Philippines. It was about 56 times during a cropping season and the total quantity of pesticide used per hectare was about 41 l of the different brands belonging to the four major pesticide groups (Gapud and Canapi, 1994; Orden et al., 1994). In addition to the adverse effects on environment and human health, such pesticide use IPM for Eggplant fruit and shoot borer increases the cost of production making eggplant expensive for poor consumers. For instance, the share of the cost of pesticide to total material input cost was 55% for eggplant and it ranked first when compared to tomato (31%) and cabbage (49%) in the Philippines (Orden et al., 1994), whereas it was 40-50% in Bangladesh (SUSVEGAsia, 2007). Hence, many farmers refrained from growing eggplant because of this pest (Gapud and Canapi, 1994). Any single method of pest management cannot achieve a level of EFSB control acceptable to producers in the region. The integrated pest management (IPM) techniques could provide satisfactory control, but it should be simple and economic. Some IPM models have been suggested in the past and the farmers were given training on IPM. However, the impact of the IPM training was ambivalent, as the farmers increased the level of pesticide use after receiving training (Potutan et al., 1997). Probably the absence of economical IPM solutions for this pest was a key constraint in the region (IPM CRSP, 2001). AVRDC – The World Vegetable Center has recently developed, validated and promoted an IPM strategy for the control of EFSB in South Asia during 2000-2005 (Alam et al., 2003; Alam et al., 2006). The IPM strategy is composed of healthy seedling production, use of resistant cultivars, and EFSB sex pheromone to continuously trap the adult males, prompt destruction of pest damaged eggplant shoots and fruits at regular intervals, and withhold 105 © JBiopest. 23 Journal of Biopesticides, 1(2):105 112 (2008)