Some factors affecting responses of four stored product beetles (Coleoptera: Tenebrionidae & Bostrichidae) to pheromones

Abstract

Males of Tribolium castaneum (Herbst), T. confusum (Duval) (Tenebrionidae), Rhyzopertha dominica (Fabricius) and Prostephanus truncatus (Horn) (Bostrichidae) secrete aggregation pheromones attractive to both sexes. Responses of the four species to synthetic aggregation pheromones were investigated in relation to age, habituation, time of day, sex and previous mating experience in an olfactometer in which odour gradients were set up in moving air. Habituation reduced pheromone response in all the species tested but all recovered to pre-habituation levels after 48 h except Tribolium spp. males. Both sexes of T. castaneum and T. confusum were responsive to pheromone immediately upon eclosion, males reaching maximum response after 19 and 21 days and females after 21 and 16 days, respectively. Pheromone response was linearly related to age of the Tribolium spp. and T. castaneum males showed a greater response than the females. Sex or having mated did not affect the responses of T. confusum, P. truncatus and R. dominica. All the pheromones evoked periodicity of response, peaking between 10.00 and 18.00 h.

Age and Sex Related Responsiveness ofTribolium castaneum(Coleoptera: Tenebrionidae) in Novel Behavioral Bioassays

“…The decreased response to aggregation pheromones over time could be related to mating and dispersal considerations including early dispersal from larval habitat and a search for unoccupied resources. This contrasts with previous research that indicates that maximum responsiveness occurs after 19 d for males and 21 d for females (Obeng-Ofori and Coaker 1990). Altered responses could be linked to preparation of individuals for bioassay, ObengOfori and Coaker (1990) aged beetles individually while this study held them in same sex cohorts.…”

“…It is a chemical that is released only by the male and shows similar attractancy for both sexes (Suzuki and Sugawara 1979). In addition, other studies have examined the relationship between chemical responsiveness and age (Dick 1937, Sokoloff 1974, Ziegler 1976) but only two paired the two to show how sex and age together relate to attraction (Arbogast andFlaherty 1973, Obeng-Ofori andCoaker 1990), showing attraction increases with age but does not vary with sex.…”

Host‐finding behaviour of Prostephanus truncatus (Horn) (Col., Bostrichidae): primary attraction or random attack?

“…However, no electrophysiological differences between males and females were detected in EAG studies (CORK et al, 1991;SCHOLZ, unpubl. data) and both pheromone components and their mixture were equally attractive to males and females in wind tunnel trials (FADAMIRO, 1995) and onechoice olfactometer experiments (OBENG-OFORI and COAKER, 1990). It is therefore probable that the differences between the sexes observed in this experiment have a behavioural, rather than a physiological, basis, i.e.…”

Effect of Age of the Intermediate Host Tribolium confusum (Coleoptera) on Infection by Hymenolepis diminuta (Cestoda)

“…Many aspects of T. confusum change markedly with age, often over relatively short time spans. Response to pheromones increases dramatically during the first 3 wk of life, then declines markedly in females but not males (Obeng-Ofori and Coaker, 1990). Egg production increases during the first 7 wk, then declines until at least 12 wk of age (Maema, 1986), although in Tribolium castaneum a general decline in egg production from about 1 to 17 wk is punctuated by periods of sharp increases (Mertz, 1969).…”