Field observational studies on circadian activity pattern of Oecophylla longinoda' (Latreille) (Hymenoptera: Formicidae) in relation to abiotic factors and mango cultivars

Field observational studies on circadian activity pattern of Oecophylla longinoda (Latreille) were carried out during two consecutive years in a mango orchard of the Sudanian zone of Benin. Preliminary results show that circadian activity of weaver ants is continuous although diurnal activity is greater than nocturnal activity. The consistency of the pattern suggests circadian internal clock regulation through light, temperature and humidity as its zeitgeber primary elements. Seasonal periodicity seems not to act on weaver ant activity between dry, rainy and harmattan seasons. Laboratory experiments now need to be implemented to check and complete these field results, and to screen for these three abiotic factors and others of potential relevance. Cultivars with thin foliage and modest canopies sheltered more nests than those with thick foliage and a dense canopy. This study raises practical issues on the use of biological control agents to improve weaver ant management and these are discussed. (Résumé d'auteur