Invasion byBactrocera dorsalisand niche partitioning among tephritid species in Comoros

Abstract

Ten economically important species belonging to the Tephritidae have been recorded in Union of the Comoros (an island nation off the coast of East Africa). Little is known about the distribution of these species and how they are affected by climatic factors in the Comoros archipelago. The main objectives of this study were to characterize: (i) the population dynamics of tephritid fruit flies in relation to season and host fruit availability and (ii) the geographic distribution of tephritids in relation to temperature and rainfall. The study was conducted during 2 years at 11 sites on three islands (Grande Comore, Anjouan, and Mohéli) in the archipelago. The site elevations ranged from 55 to 885 m a.s.l. At each site, flies were collected weekly in eight traps (four different lures, each replicated twice). Fruit phenology was also recorded weekly. The dominant tephritid species detected was the invasive Bactrocera dorsalis Hendel followed by Ceratitis capitata Wiedemann. Tephritid species were generally more abundant during the hot and rainy seasons than during the cold and dry seasons. Bactrocera dorsalis numbers were higher on Grande Comore than on the two other islands. On Anjouan and Mohéli, B. dorsalis numbers were very low in 2014 but sharply increased in 2015, suggesting a recent invasion of these islands. Abundances were significantly related to the fruiting of mango, strawberry guava, and guava for B. dorsalis and to the fruiting of mango, guava, and mandarin for C. capitata. Bactrocera dorsalis was more abundant in hot and humid low-altitude areas, while C. capitata was more abundant in dry medium-altitude areas, suggesting the occurrence of climatic niche partitioning between the two species.

Changes in phytophagous insect host ranges following the invasion of their community: Long‐term data for fruit flies

“…This community is the result of a succession of Tephritidae invasions, and it may be affected by additional invasions. For example, another Tephritidae species, B. dorsalis , is present in various areas in the Indian Ocean (Hassani et al., 2016), and there is a high risk of this species invading La Réunion. This species is known to be highly polyphagous and competitive (Clarke et al., 2005) and would therefore be expected to compete with the Tephritidae species already present on La Réunion.…”

“…This community is the result of a succession of Tephritidae invasions, and it may be affected by additional invasions. For example, another Tephritidae species, B. dorsalis, is present in various areas in the Indian Ocean (Hassani et al, 2016), and there is a high risk of this species…”

Niche shift of tephritid species after the Oriental fruit fly (Bactrocera dorsalis) invasion in La Réunion

“…Despite the disastrous economic impact due to loss of fruit production and the associated export markets, the invasion of B. dorsalis provides a unique opportunity for observing and evaluating the role of niche differentiation in community assembly in real‐time. The impact of B. dorsalis on Ceratitis species has been observed in other regions, where the dominance of B. dorsalis caused a niche displacement but never to the point of extinction because established insect populations were generally maintained in ‘refuge niches’ (Duyck, Sterlin, et al., 2004; Ekesi, Billah, Nderitu, Lux, & Rwomushana, 2009; Hassani et al., 2016; Mwatawala et al., 2009a, 2009b) . So far, no studies have described the effect of the introduction of B. dorsalis on the population dynamics and host range of a resident B. zonata population.…”

Variation in physiological host range in three strains of two species of the entomopathogenic fungus Beauveria

“…catoiri (Guérin-Méneville) endemic in Réunion, the Indian Ocean cucumber fly, Dacus demmerezi (Bezzi) and the melon fly, Zeugodacus cucurbitae (Coquillett). Tests were also carried out on the oriental fruit fly, Bactrocera dorsalis (Hendel), an invasive species not recorded in Réunion at the time of the study, but present in most islands in the western region of the Indian Ocean, including Comoros [ 35 ]. Fruit fly strains of B .…”