No abstract

The results suggest that palm wine alcohol extracts of senesced banana leaf material could be used to lure adult C. sordidus to traps in the field, as part of an ethnobotanical-based approach for C. sordidus management on smallholder farms. © 2018 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The effects of host and non-host plant odours on the foraging responses of the banana weevil, Cosmopolites sordidus (Germar), were investigated in the laboratory through arena and olfactometer bioassays. Contrary to previous reports that banana rhizome and pseudostem were the most attractive parts to the weevil, dead leaves were most preferred. Comparison of dead banana leaves with dead leaves of other plants showed that attractant odours were present in yam, cocoyam and dead grasses but absent in cocoa and soybean leaves. Complete leaf senescence while the leaf was attached to the mother plant proved necessary for the development of the dead-leaf-based odours but the involvement of microbial organisms could not be demonstrated. It is possible that dead-leaf-based attractants could be used in combination with microbials such as entomogenous fungi and nematodes in integrated management of C. sordidus.

The principal active component produced by highly attractive senesced host banana leaves, Musa spp., for the banana weevil, Cosmopolites sordidus, is shown by coupled gas chromatography‐electroantennography (GC‐EAG), coupled GC‐mass spectrometry (GC‐MS), chemical synthesis and coupled enantioselective (chiral) GC‐EAG to be (2R,5S)‐theaspirane. In laboratory behaviour tests, the synthetic compound is as attractive as natural host leaf material and presents a new opportunity for pest control.

Female Aphidius rhopalosiphi De Stefani Perez reared on Rhopalosiphum padi (Linnaeus) made equal numbers of encounters with another suitable host aphid (Sitobion avenae (Fabricius (both Homoptera: Aphididae))) in arenas where the aphids were on either pieces of wheat leaf or moist filter paper. However, the number of oviposition stabs made in arenas with wheat was far higher than with filter paper, demonstrating the importance of host-plant cues in the acceptance of the aphids by the parasitoid. Diet reared aphids (even if subsequently fed on wheat) appeared to be accepted more readily than totally wheat reared individuals. In another arena experiment, there were more encounters with and more stabs made into both S. avenae and a non-host aphid (Myzus persicae (Sulzer)) on wheat than on Brussels sprouts (a host plant of M. persicae), again showing the over-riding importance of host-plant cues.