Three species of fruit flies cause serious damage to cucurbit crops on Reunion Island: Bactrocera cucurbitae (Diptera: Tephritidae) (Coquillett 1899), Dacus ciliatus (Loew 1901), and Dacus demmerezi (Bezzi 1917). To control them, a program of agroecological management of cucurbit flies has been implemented based on the application of Synéis-appât, especially spot sprays on corn borders. However, the high rainfall on Reunion Island limits the long-term efficiency of the bait; in addition, this method cannot be used for large chayote trellises, because corn borders cannot be planted around them. The aim of this study was to design a bait station adapted to prevailing conditions on Reunion Island. An 'umbrella trap' tested in Taiwan was used as a reference to compare its efficacy with our local bait station. Experiments were conducted in field cages on B. cucurbitae to test different characteristics of bait stations and to construct one using local materials. Results were validated in the field. The attractiveness of the bait station was related mainly to the color of the external surface, yellow being the most attractive color. The efficacy of the bait station with respect to fly mortality was found to be linked to the accessibility of the bait, and direct application of Synéis-appât on the bait station was found to be the most efficient. In the field, B. cucurbitae were more attracted to the local bait station than to the umbrella trap, while the two other fly species displayed equal attraction to both trap types. Our local bait station is a useful alternative to spot sprays of Synéis-appât and is now included in a local pest management program and is well accepted by farmers.

The tritrophic interactions between mangoes (Mangifera indica), two frugivorous fly species of great economic significance, Bactrocera invadens and Ceratitis cosyra, and weaver ants (Oecophylla longinoda) were studied in Benin. We investigated whether Oecophylla cues affect B. invadens and C. cosyra oviposition behaviour compared to natural conditions. Results show that on un-marked fruits, both C. cosyra and B. invadens adults have different active periods and length of oviposition, both under laboratory and field conditions. Compared to their landing on unmarked fruits at 7h after confinement, 46% of B. invadens refrained from landing on fruits marked with Oecophylla cues, while C. cosyra reduced its landing by 73%. In contrast to the un-marked fruit, both tephritid species significantly reduce oviposition duration and oviposited less in fruits when weaver ants had patrolled on them before. Moreover, no significant difference was detected between C. cosyra and B. invadens, in number of pupae produced, when confined with ant-marked fruits. Ecological and behavioural implications of our observations are discussed.

No abstract

Weaver ants, Oecophylla spp., are known to positively affect cashew, Anacardium occidentale L., raw nut yield, but their effects on the kernels have not been reported. We compared nut size and the proportion of marketable kernels between raw nuts collected from trees with and without ants. Raw nuts collected from trees with weaver ants were 2.9% larger than nuts from control trees (i.e., without weaver ants), leading to 14% higher proportion of marketable kernels. On trees with ants, the kernel: raw nut ratio from nuts damaged by formic acid was 4.8% lower compared with nondamaged nuts from the same trees. Weaver ants provided three benefits to cashew production by increasing yields, yielding larger nuts, and by producing greater proportions of marketable kernel mass.