Basic biology and artificial rearing of Bactrocera pyrifoliae (Diptera: Tephritidae), a pest of peaches and plums in northern Vietnam

In this study, the basic biology of and artificial rearing techniques for Bactrocera pyrifoliae (Drew and Hancock), a pest of peaches and plums in high-elevation areas of northern Vietnam and Thailand, were investigated for 5 years. Bactrocera pyrifoliae was found only between elevations of 1000 and 1500 m, heavily infesting peaches and plums from early June to harvest in mid-July The durations of the egg, larval and pupal stages were determined under controlled environmental conditions in the laboratory, indicating that B. pyrifoliae is a multivoltine species. Larvae were successfully reared on a carrot and corn powder-based diet. Determinations of the appropriate adult density in colony cages, and also optimal temperature conditions for holding adults, were made. Bactrocera pyrifoliae performed better when the temperature was lowered during the night, as would be expected for a species adapted to temperate-like environments. Interestingly, adults originating from field-collected pupae emerged with a 3:1 female-biased sex ratio. Laboratory colonies, by generation seven, appeared to exhibit signs of inbreeding depression and required periodic incorporation of wild insects to restore egg hatch. To develop sound management techniques for populations of B. pyrifoliae infesting peaches, alternate commercial and native hosts infested outside the peach and plum fruiting season must be identified or some form of overwintering mechanism such as reproductive diapause be discovered. Documentation of mating behaviour in the field (a key to developing efficient traps), improvement in fertility in laboratory colonies, and eventually sterile insect technique-based integrated pest management for pest population management in the expanding low-chill temperate fruit-growing areas of northern Vietnam are also needed.