Mechanisms contributing to the competitive success of the invasive fruit fly Bactrocera invadens over the indigenous mango fruit fly, Ceratitis cosyra: the role of temperature and resource pre‐emption

Abstract

We investigated the influence of temperature and infestation sequence on interspecific competition between two fruit flies: an invasive (Bactrocera invadens Drew, Tsuruta & White, (B) and a native (Ceratitis cosyra Walker, C) (both Diptera: Tephritidae) species. Mango fruits [Mangifera indica L. (Anacardiaceae)] were co‐infested with larvae at different constant temperatures (15, 20, 25, and 30 °C) and relative humidity of 50 ± 8%, using different infestation sequences at each temperature (BC together; BC/CB 1, 2, and 3 days apart). There were significant effects of competition in most experimental treatments, resulting in reduced larval survival, pupal mass, and adult emergence for both species. At most of the infestation/temperature combinations, C. cosyra was clearly the inferior competitor. The only exception was at 20 °C when the outcome depended on the sequence of infestation: no C. cosyra survived when the sequence was BC, but more C. cosyra than B. invadens survived when it was CB. At 15 °C, all C. cosyra larvae died, while the development of B. invadens was prolonged and adult emergence reduced. We conclude that resource pre‐emption and fluctuations in temperature in mango agroecosystems help to explain observed shifts in dominance between B. invadens and C. cosyra on mango in many parts of Africa. The small window of competitive superiority for C. cosyra at 20 °C and CB infestation sequence, together with other factors such as fecundity and alternative hosts, may allow for co‐existence in some environments.

Anastrepha ludens and Anastrepha serpentina (Diptera: Tephritidae) Do Not Infest Psidium guajava (Myrtaceae), but Anastrepha obliqua Occasionally Shares This Resource With Anastrepha striata in Nature

“…Coinfestation and scramble competition are often exhibited by polyphagous tephritids because of diet overlap (Duyck et al 2004). Species dominance in tephritids depends on temperature, latitude and longitude, humidity, host fruit quality, and other factors that inßu-ence larval developmental time (Duyck et al 2004, 2006; Rwomushana et al 2009;Ekesi et al 2009). It would be interesting to study which of these factors inßuences the outcome of species dominance in guava between A. fraterculus and A. striata.…”

Translating olfactomes into attractants: shared volatiles provide attractive bridges for polyphagy in fruit flies

“…Our research concentrated on Tephritidae, a family of fruit flies of which several members are highly invasive, and threaten horticultural production and livelihoods in large parts of the tropics and subtropics. Whereas many species appear polyphagous, they generally display a stronger preference for a limited few hosts (Bush 1969;Rwomushana et al 2009). How this is regulated by the sense of smell, and whether flies cue in on specific host-signifying volatiles in a complex blend, or rely on general compounds in particular combinations and ratios, is not known (Visser 1986;Bruce et al 2005).…”

Demographic parameters of the two main fruit fly (Diptera: Tephritidae) species attacking mango inCentralTanzania

“…() where it was shown that B. invadens is displacing C. cosyra in certain parts of Kenya, with temperature being one of the mechanisms contributing to the competitive success of B. invadens (Rwomushana et al. ). Duyck et al.…”

“…(), while Rwomushana et al. () showed significant effects of temperature on competitive success of B . invadens compared with C .…”