Comparative Biology of Coconut Leaf Beetle (Clb) Brontispa longissimi (Gestro) (Coleoptera: Chrysomelidae) on Selected Coconut Varieties

Abstract

Comparative biology and development study of B. longissima Gestro was conducted using different coconut varieties namely: Baybay tall (BAYT) green, Baybay tall (BAYT) brown, Malayan Red dwarf (MRD), Malayan Yellow dwarf (MYD), Albuera dwarf (ALD), and Tacunan dwarf (TACD) varieties was investigated in the laboratory. The duration of the developmental period of B. longissimi was influenced by the different coconut varieties used as host plant. Duration from egg laying to hatching of eggs of B. longissima on tall varieties ranged from 3 to 5 days, while on dwarf varieties it took 4 to 5 days. In all varieties, Brontispa beetles underwent 5–6 instars. In addition, it was observed that the fifth and sixth instars took a longer time period compared to other instars. The total mean developmental period of Brontispa on BAYT (green and brown) was shorter in days compared to all dwarf varieties except to ALD. The results generally showed that BAYT (green and brown) seemed to be a preferred variety. There was considerably higher larvae mortality in dwarf variety like MRD (40%) than those reared in the BAYT green and brown (22.21%, 19.12%), respectively. Beetles reared on BAYT (brown) also had the highest fecundity which was statistically different from the rest of the varieties. In addition, results showed that adults reared in both BAYT (green and brown) had the highest longevity observed compared to other varieties