Sustainable pest management requires the use of ecosystem-friendly control options (e.g. entomopathogens) coupled with target-specific application methods. Here we investigate the susceptibility of the sorghum chafer (Pachnoda interrupta, Olivier) to Metarhizium sp., isolated from dead P. interrupta under field conditions over several years. Target-specific trapping was achieved using Japanese beetle traps or locally made autoinoculation devices, with methyl salicylate or banana as an attractant. Of the attracted and infected beetles, 49% mortality was achieved during October 2005 and 71% during July 2006, while the corresponding mortality in control treatments was 13 and 5%, respectively. We further confirmed that the mortality of the beetles was due to the fungal treatment as 50 and 80% of the dead beetles showed mycosis, respectively. The performance of the pathogen was also investigated in an autodissemination device in 2008 and 2009, where the beetles that were attracted passed through an inoculation chamber. Of the attracted and infected beetles in the autodissemination device, 58.5% (October) and 90.9% (July) were dead within 15 days after treatment. Control mortality was only 3 and 2%, respectively. The potential for horizontal transmission was investigated, where 47% (October) and 59% (July) of the beetles exposed to the pathogen through horizontal transmission were killed. The pathogen was found to be viable for more than 3 days in the field. Our results show that Metarhizium sp. has potential as a biological control agent, and for achieving autodissemination using the target pest as the vector.

Behavioural and antennal responses of the sorghum chafer Pachnoda interrupta (Olivier) were tested to the synthetic compounds, such as eugenol, methyl salicylate, methyl anthranilate, isoamyl acetate and butyl butyrate. In the field, all odour-baited traps, except isoamyl acetate applied on cotton dispensers, were significantly more attractive than blank (unbaited) traps and all compounds, except isoamyl acetate, elicited dose-dependent responses in both male and female antennae. Dispenser type (cotton wick or rubber septum), trap location (inside or outside sorghum fields) and season (mating/July or feeding/September) affected the performance of the different compounds as lures. In July, methyl salicylate applied on cotton was the most attractive lure, whereas the most attractive treatments in September were eugenol and isoamyl acetate on rubber septa. Possibly due to odour and visual competition from the sorghum plants, traps placed outside the sorghum fields caught significantly more beetles than traps placed inside the fields. The trapping efficiency of a locally produced trap was found not to be competitive with that of the commercially available Japanese beetle trap. Overall, the results suggest that trapping with semiochemicals has a potential in sorghum chafer management, either for mass trapping and/or as part of an integrated pest management programme.