Bioecology of the fruit fly Dacus punctatifrons on tomato and host range expansion

N.N. Ntonifor and J.N. Okolle

Abstract

Investigations on the oviposition/oviposition behaviour, developmental studies and general ecology of Dacus punctatifrons were conducted in the laboratory and tomato fields in Buea, Cameroon. This study revealed that D. punctatifrons has clearly expanded its host range to tomatoes (Lycopersicon esculentum Mill) in Cameroon. The female flies oviposit into unripe tomato fruits to deposit a cluster of 3–10 eggs, which hatch 1–3 days later. The larvae feed on the fruit pulp until about pupation, then drop either singly or together with the enclosing damaged fruit from which they emerge, wriggle and burrow 2–5 cm below the soil surface to pupate. Pupal and total developmental periods were about 12 and 25 days, respectively. Mean adult longevities were 11.75 and 16.85 days for males and females, respectively. A range of 1–3 oviposition punctures and 1–12 larvae were found per fruit. Generally, the percentage of infested plants per field varied with location but was often <40% within 1–3 weeks after fruiting, irrespective of site; this eventually increased beyond 80% in most fields. The percentage of infested fruit also varied with location but was often <20% from 1–7 weeks after fruiting before drastically increasing to around 60% beyond week 7 regardless of site. The major natural enemies of the flies observed in this study were various ants and bird species. These results are discussed in the light of possible options for cost-effective, environmentally friendly and sustainable management strategies for D. punctatifrons that currently inflicts heavy damages on tomatoes in Cameroon.

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