Development of Lures and Local Traps and Their Application for Field Management of Pachnoda Interrupta (Olivier) (Coleoptera: Scarabaeidae) in Sorghum in Ethiopia

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Date

2014-06

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Addis Ababa University

Abstract

Sorghum (Sorghum bicolor (L.) is one of the major nutritious cereals in Africa widely cultivated in eastern regions including Ethiopia. Sorghum chafer Pachnoda interrupta (Coleoptera: Scarabaeidae) is a polyphagous insect whose adults are serious pests of sorghum (Sorghum bioclor) in the fields. The damage by the sorghum chafer during the milky stage of the seed contributed to low production of sorghum in many regions of Ethiopia. The adult beetle uses visual and olfactory cues (specific blends of compounds) in their search for food sources, mate selection, and oviposition sites. The present study focused on evaluation of the attractiveness of lures and catch performance of locally designed cheap traps in P. interrupta field management strategies in naturally infested regions of northeastern Ethiopia. Optimal and constant release rates of previously identified volatile compounds phenylacetaldehyde, 2,3-butanediol, methyl salicylate, eugenol, isoamyl acetate were determined from dispensers in the laboratory. Field experiments testing the efficacy of different single- and multi-component baits and different types of traps were conducted in close collaboration with farmers. Various blends/single compounds and the natural attractant banana fruit were tested in both the mating season in July and the feeding season for newly emerged adults in October. Different locally affordable trap designs were evaluated and compared with the previously proven efficacy of a commercial Japanese beetle trap. In addition, novel attractant blends were also tested in the field. These blends were synthetic replicas of odors from overripe banana fruit and fermentation volatiles identified by solid-phase micro extraction combined with gas chromatography-mass spectrometry analysis in the laboratory. After a two-choice behavioral bioassay, the promising component blends tested in the laboratory were evaluated in the mating and feeding seasons in 2013. The iv results of the beetle catch revealed that traps baited with the multiple-dispenser blend of the five compounds, and the mixture of the five compounds formulated in one dispenser, were the best lures. It was also demonstrated that the longevity of the lure in the field coincided with the flying period of P. interrupta during the mating and feeding seasons. Among the field tested trap designs, four locally affordable cheap traps were found to be as efficient as the commercially produced Japanese beetle trap in trapping P. interrupta . Among the blends from volatile chemicals released from overripe banana and fermentation volatiles, a blend of eleven compounds was proven effective in behavioral responses both in the laboratory choice bioassay and the P. interrupta trapping in the field. This indicates that the compounds identified are behaviorally relevant and can be used as potential candidates for further field tests. In conclusion, the work has produced both efficient and cheap local traps baited with best attractant compounds blend.

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Keywords

Development of lures and local, Traps and their application

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