Habitat selection by fruit flies (Diptera: Tephritidae) in a tropical agroecosystem in Papua New Guinea

Abstract

Habitat selection by fruit flies (Diptera: Tephritidae) along disturbance gradients of tropical agroecosystems has ecological significance. There have been extensive studies of fruit flies in agricultural systems and in natural forests. Here we examined the species preference regarding three vegetation types: cocoa plantation, secondary forest and primary forest, using methyl eugenol (ME) and cue-lure (Cue). We also quantified the efficiency of the two para-pheromones for fruit fly sampling within different habitats. The total number of individuals collected were 685 respectively in cocoa plantation, 1338 in primary reserved forest and 1589 in secondary forest. Species diversity reached its highest value in cocoa plantation (H=3.59) followed by secondary forest (H=3.17) and least diverse in primary forest (H=2.94). Total species richness (pooled data per site) was identical in primary forest and secondary forest (10 species each) but slightly higher in cocoa plantation (12 species). No individuals of Bactrocera kirki and Bactrocera obliqua were trapped with ME but only in cue-lure. Vice versa, nil individuals of Bactrocera curvifera and Bactrocera laticaudus were attracted to cue-lure but only to ME. Dacus longicornis (1.09±0.162), Zeugodacus cucurbitae (3.00±0.61) and Zeugodacus sp.n (1.88±0.35) were more responsive to cue-lure than to ME (0.181±0.121, 1.750±0.463, 0.592±0.186). Temperature (F-value = 11.34, p0.05). All three abiotic factors did not have any significant interaction with vegetation on ME abundance (p>0.05). This study finds that there is low species composition within a typical tropical agroecosystem and thus similar species can be widely distributed across a contiguous habitat. However, the abundance was significant among the three study habitats. Temperature, wet season and seasonal fruit availability exerted ecological impact on fruit fly population and their distribution among the three study sites.