Co-existence of Bactrocera dorsalis and B. kandiensis (Diptera: Tephritidae) in Karutha kolumban mango (Mangifera indica) variety.

Abstract

Fruit flies are a menace to global agriculture. In Sri Lanka, Bactrocera dorsalis Hendel is an invasive species, and B. kandiensis Drew and Hancock is an endemic fruit fly species. There is very little information available about how fruit flies co-utilize resources for oviposition. This work was thus carried out to study the co-utilizing potential of Karutha kolumban (Kc) mangoes by B. dorsalis and B. kandiensis for oviposition. A total of 340 Kc mangoes were identified as infected, which were collected in eight randomly selected mango cultivations every two months (on the availability of fruits) in 2022. Each fruit was incubated individually in plastic containers (18 × 14 × 13 cm) with pre-sterilized sand and muslin cloth cover (25oC, RH: 75–85%). After fifteen days, the number of adults (both species) that emerged per fruit was counted. Species were identified using taxonomic keys (B. correcta (Bezzi), B. latifrons (Hendel) were recorded as additional species). Among the number of fruit flies that emerged from incubated fruits, B. dorsalis (76%, n = 392) was higher than that of B. kandiensis (24%, n = 123). The utilization of Kc fruits by both species was 58% (Kc:n = 200), while only B. dorsalis used 22% (Kc:n = 78) and only B. kandiensis used 18% (Kc:n = 62) of mangoes for their oviposition and offspring performance. Among the emerged flies from co-utilized Kc, the highest number of individuals represented B. dorsalis (64%), followed by B. kandiensis (36%). Emerged adults of both species were high in the late fruiting season and in the sites of the intermediate zone. The enduring co-utilization of resources by B. dorsalis and B. kandiensis is highlighted in this work, and it is vital to know this relationship in order to develop integrated control strategies for both fruit fly species.