Evaluating the potential of luring pheidole megacephala using food baits to manage xylosandrus compactus in Uganda

Abstract

The black coffee twig borer (BCTB ) Xylosandrus compactus (Eichhoff) is an economically important pest of Robusta coffee in Uganda. In this study, the predatory ant, Pheidole megacephala, was evaluated for potential use as a biological control agent against X. compactus. The research tested hypotheses that (1) P. megacephala feeds on all stages of X. compactus, (2) P. megacephala can enter galleries of BCTB inside coffee twigs in search for the prey and (3) presence of P. megacephala on infested twigs reduces populations of BCTB in the galleries (4) P. megacephala prefers certain food baits and (5) P. megacephala presence on infested Robusta coffee reduces incidence and abundance of BCTB in the galleries. In a petri dish feeding bioassay, between 6 th and 22nd July 2014, P. megacephala preyed upon all the stages of BCTB without any indication of preference for any stage. In a bioassay from 4th to 6th August, 2015 to determine if P. megacephala can enter galleries of X. compactus inside Robusta coffee twigs, the researcher found that the predator was unable to enter the galleries. In a field cage bioassay between 16th September and 16th October 2014, P. megacephala reduced the population of all life stages of BCTB on Robusta coffee twigs by almost 22 fold compared to untreated control. In screening baits for attractiveness between 30th and 31st July 2015, the results revealed that P. megacephala is attracted to honey, fish, beef and Royco but 25, 6.5 and 4.4 times more to honey than to Royco, fish and beef respectively. In determination if P. megacephala presence on infested Robusta coffee reduces incidence and abundance of BCTB in the galleries between 3 rd August and 3rd September 2015, the findings indicate that P. megacephala significantly reduces X. compactus incidence in the Robusta coffee field and also reduces X. compactus abundance though not significantly. In view of these findings, the study concludes that P. megacephala is an indiscriminate predator of all growth X. compactus stages, and, though unable to enter BCTB galleries, the predator reduces X. compactus population on infested twigs. Exploitation of P. megacephala in the biological control of BCTB on coffee and other crops would require additional studies on how to enhance presence of the predator on the infested crop and to establish if blending sugar and protein baits would produce synergistic attractiveness to predatory ants.