Occurrence of sexuals of African weaver ant (Oecophylla longinoda Latreille) (Hymenoptera: Formicidae) under a bimodal rainfall pattern in eastern Tanzania.

The African weaver ant, Oecophylla longinoda, is being utilized as a biocontrol agent and may also be targeted for future protein production. Rearing of mated queens in nurseries for colony production is needed to cater for such demands. Thus, newly mated queens must be collected for use as seed stocks in the nurseries. To collect mated queens efficiently it is important to identify when sexuals occur in mature colonies. We studied the occurrence of sexuals in O. longinoda colonies for 2 years in Tanga, Tanzania, a region characterized by a bimodal rainfall pattern. We found that O. longinoda sexuals occurred almost throughout the year with abundance peaks from January to April. Production of sexuals appeared to be triggered by rainfall, suggesting that populations in areas with long rainy periods may show prolonged mating periods compared to populations experiencing extended dry periods. The bimodal rain pattern may thus cause a low production over a long period. The average yearly production of queens per tree and per colony was estimated to be 449 and 2753, respectively. The average number of queens per nest was 17. Worker abundance declined from January to March with minimum by the end of this period, being inversely proportional to the production of sexuals. In conclusion, mated queens may be collected almost throughout the year, but most efficiently by the onset of the long rainy season when the majority disperse.