Longevity and pheromone output in stored-product Bostrichidae

Abstract

AbstractInformation on longevity and on the effect of ageing on pheromone signalling in Bostrichidae infesting stored products is important because pheromones play a crucial role in mediating aggregation by the species in storages. The longevity of starved and unstarvedProstephanus truncatus(Horn) andRhyzopertha dominica(Fabricius) were determined at 28±1°C, 65±2% RH and L12:D12 cycle. Additionally, the effects of ageing on rate of pheromone emission were investigated inR. dominicaby comparing emission rates of the aggregation pheromones Dominicalure-1 (DL1) and Dominicalure-2 (DL2) released by adult males ranging from 4, 8, 12, 24 and 48 weeks of age. Mean survival time of starved male and femaleP. truncatuswas 8.6±0.6 and 9.1±0.4 days, respectively. StarvedR. dominicamales lived for 5.7±0.2 days, and females for 4.7±0.1 days. However, mean survival times were not significantly different for starved males vs. females of either species. Mean survival time of unstarved male and femaleP. truncatuswas 27.5±2.0 and 18.0±3.3 weeks, respectively, and for unstarved male and femaleR. dominicawas 26.1±2.8 and 16.7±2.9 weeks, respectively. Difference in mean survival times of unstarved males vs. females in bothP. truncatusandR.dominicawere significant. Between species, no significant difference was observed in mean survival time between unstarved males ofP. truncatusorR. dominica, nor between females of both species. Rate of pheromone emission inR. dominicawas higher when the insects were relatively young (4, 8 and 12 weeks old), but declined by almost 55% in treatments where the insect were at about 24 or 48 weeks old, suggesting that recruitment potential ofR. dominicamight reduce substantially as the insects age.