Efficacy of fish- and hydramethylnon-based baits for conservation of the African weaver ant Oecophylla longinoda (Hymenoptera: Formicidae) during cashew off-seasons in Tanzania Moses I. Olotu 1,2 , Hannalene du Plessis 3 , Zuberi S. Seguni 4 , Sunday Ekesi 1 and Nguya K. Maniania 1 * 1 International Centre of Insect Physiology and Ecology (icipe), PO Box 30772-00100, Nairobi, Kenya; 2 Mkwawa University College of Education (MUCE), PO Box 2513, Iringa, Tanzania; 3 North-West University, Private Bag X6001, Potchefstroom, South Africa; 4 Mikocheni Agricultural Research Institute (MARI), PO Box 6226, Dar-es-Salaam, Tanzania (Accepted 16 February 2015) Abstract. The efficacy of fish- and hydramethylnon-based baits for conservation of the African weaver ant (AWA) Oecophylla longinoda Latreille was evaluated at orchards in Bagamoyo and Mkuranga districts, Coast region of Tanzania, during the cashew off- seasons in 2011 and 2012. The baits were applied at monthly intervals; the dynamics of AWAwere monitored by counting the number of leaf nests/tree and the colonization trails on main branches. The numbers of leaf nests recorded before baiting ranged between 3.5 and 5.3 and were not significantly different at both sites and in both seasons; after baiting, they ranged between 3.2 and 11.6 at Bagamoyo and between 3.0 and 10.2 at Mkuranga. The colonization of AWA trails recorded before baiting was also not significantly different at both sites and in both seasons and ranged between 37.9 and 50.0%; after baiting, this ranged between 35.9 and 75.1% at Bagamoyo and between 34.6 and 79.2% at Mkuranga. The provision of fish- and hydramethylnon-based baits can effectively contribute to the conservation of AWA during the cashew off-seasons. The fish- based bait is cheaper and more easily affordable by local farmers and can, therefore, be used as an alternative diet for AWA at this time. Key words: Oecophylla longinoda, food source, Pheidole megacephala, insecticide, manage- ment, abundance, colonization Introduction The African weaver ant (AWA) Oecophylla longinoda Latreille (Hymenoptera: Formicidae) is an effective agent in Tanzania for the biocontrol of sap-sucking pests in coconut (Varela, 1992; Seguni, 1997) and cashew (Olotu et al., 2012). It also effectively controls pests of mango in Be ´nin (Van Mele et al., 2007) and of cashew in Ghana (Dwomoh et al., 2009). In East Africa, AWA occurs naturally in more than 80 species of shrubs as well as in wild and cultivated trees along the coastal area of Kenya *E-mail: nmaniania@icipe.org International Journal of Tropical Insect Science Vol. 35, No. 2, pp. 90–95, 2015 doi:10.1017/S1742758415000144 q icipe 2015