Author : Franciscus Xaverius Wagiman Adisubroto

Summary : The chili aphid, Aphis gossypii Glover (Homoptera Aphididae) (here after abbreviated as AG), is vector of the chili veinal mottle virus (CVMV) and is main pest of chili in Malaysia. The aphidophagous Menochilus sexmaculatus Fabricus (Coleoptera: Coccinellidae) (here after abbreviated as MS) is a well known predator of the aphid and hereby its ecological characteristics and predatory performance were assessed. In nature, MS maintains its population on aphids of corn, beans, sambau weed and other plants. The predator searched its prey in random manner and tended to aggregate in high prey density. Both prey and predator were distributed in a clumped pattern. Larval and adult MS showed no preference for any prey stages and prey species. However, there was a weak preference for AG over Aphis craccivora Koch. MS was very voracious; the larva (1st, 2nd, 3rd and 4th instar) and adult consumed 8, 43, 46 125 and 275 TIES of AG per day, respectively. The mimimum prey requirement for oviposition was 50 TIES per day. The adult survived well when supplied with 10 TIES per day. The average fecundity was 378 to 745 eggs, depending on aphid prey species (A. craccivora and Hysteroneura setariae (Thos)). The predator numbers increased at the rate (r (subscript m) of 0.1663 to 0.2116, while a higher r (subscript m) for the prey, AG, was calculated to be 0.4097 to 0.4645. The predator exhibited a delayed density-dependent relationship with the prey as indicated by a strong functional response of Holling's Type II and a direct numerical response to AG. In the field cages, MS was able to eliminate it prey (AG) population within 9 days given the initial ratio (mated female MS: AG) of 1:6,4000. In the open field, AG population was suppressed completely within three weeks given to the ratio (predator:prey) of 1:50. Results of the study may contribute in developing biological control programme of aphid vector in Malaysia and other countries where the MS is found.