THE RESPONSES OF PROSTEPHANUS-TRUNCATUS (COLEOPTERA, BOSTRICHIDAE) AND SITOPHILUS-ZEAMAIS (COLEOPTERA, CURCULIONIDAE) TO PHEROMONE AND SYNTHETIC MAIZE VOLATILES AS LURES IN CREVICE OR FLIGHT TRAPS
Rj. Hodges et al., THE RESPONSES OF PROSTEPHANUS-TRUNCATUS (COLEOPTERA, BOSTRICHIDAE) AND SITOPHILUS-ZEAMAIS (COLEOPTERA, CURCULIONIDAE) TO PHEROMONE AND SYNTHETIC MAIZE VOLATILES AS LURES IN CREVICE OR FLIGHT TRAPS, Bulletin of entomological research, 88(2), 1998, pp. 131-139
Flight traps and crevice traps for catching Prostephanus truncatus (Ho
rn) and Sitophilus zeamais Motschulsky were studied in Kenya. The trap
s were baited with pheromones of these beetles, with or without synthe
tic maize volatiles. Ln the case of P. truncatus, which has a two comp
onent pheromone consisting of Trunc-call 1 (T1) and Trunc-call 2 (T2),
the components were tested singly or in a 1:1 combination. The additi
on of synthetic maize volatiles to pheromone traps did not result in a
n increase in trap catch of either S. zeamais or P. truncatus. The phe
romone of S. zeamais was an effective lure in both crevice and flight
traps but the actual numbers captured were low. Captures with traps ba
ited for P. truncatus were much greater. The response of P. truncatus
to the two components of its pheromone was affected by the type of tra
p used. Crevice traps baited with either component alone caught fewer
beetles than those baited with a mixture. in contrast, flight traps ba
ited with T2 or the mixture were equally effective while traps with on
ly T1 caught significantly fewer than either of these. These observati
ons clarified apparent discrepancies between earlier studies in Tanzan
ia and Mexico and are used to derive an hypothesis about the roles of
T1 and T2; T2 appears to be a long-range attractant and T1 important f
or modifying the response to T2 to facilitate close-range orientation.
Adult P. truncatus arriving at the traps were sexed, and in both flig
ht and crevice traps the majority of captures were females even though
in the experimental maize cribs the beetles were present in a roughy
equal sex ratio. The role of the pheromone is discussed in the light o
f this observation.