Seasonal Occurrence of the Durian Fruit Borer, Mudaria Magniplaga Walker (Lepidoptera: Noctuidae)

Abstract

The durian fruit borer, Mudaria magniplaga Walker, is the most important insect pest of durian (Durio zibethinus Murray) in Malaysia. Since the larva of M. magniplaga is known to feed only on durian fruit which are in season once or twice a year, it is necessary to understand how the phenology of the pest is related to that of the host's. Studies were carried out to: (l) determine the species of Mudaria infesting durian, (2) examine the phenological relationship between M magniplaga and durian, (3) investigate diapause in M magniplaga. For the taxonomic study, moths were obtained from light traps and by rearing from infested durian fruit and flower buds. Based on the forewing size and pattern, and dissection of the male genitalia two species of Mudaria were identified of which one was M. magniplaga and the other an unknown (probably new) species of Mudaria. Of the specimens from the light traps, 230 were M magniplaga and 5 were Mudaria sp.; all 823 specimens from fruit were M magniplaga; and from the flower buds 5 were M magniplaga and 91 were Mudaria sp. From the results it was concluded that: (1) besides fruit M magniplaga also infests the flower bud of durian, (2) the Mudaria sp. found infesting flower buds does not infest durian fruit, (3) the high proportion of Mudaria sp. may indicate either an adaptation by this species to durian flower buds or that the phenology of M magniplaga was not in synchrony with that of the buds during the study period.