Mate recognition in the Aphis fabae complex: daily rhythm of release and specificity of sex pheromones

Abstract

The two subspecies of the host‐alternating black bean aphid, Aphis fabae Scopoli, used in this study have different secondary host plants but reproduce sexually in autumn on the same host plant, spindle, Euonymus europaea L. In both Aphis fabae fabae Scopoli and A. f. solanella Theobald the percentage of adult mating females (oviparae) calling (releasing sex pheromone) each day increased with age up to day 8. During the course of a day the mating females of A. f. solanella called most actively early in the morning and then showed a gradual decrease in calling activity. In contrast, few A. f. fabae called early in the day and were most active around midday, after which the incidence of calling decreased slightly, with 50% still calling in the evening. In both taxa the activity of the males in the absence of mating females paralleled the calling activity of their respective females. In an olfactometer, males showed a marked preference for the sex pheromone released by conspecific females over that of the other subspecies and did not respond to the odour of spindle. Thus, as in the other species of aphids there are specific mate recognition systems in A. f. fabae and A. f. solanella, which are likely to reduce the incidence of hybridisation.

Experimental hybridisation between Aphis grossulariae and Aphis triglochinis (Sternorrhyncha: Aphididae)

“…Natural prezygotic isolating mecha nisms might be rather sophisticated and fragile Guldemond & Dixon, 1994;Thieme & Dixon, 1996), and be easily circumvented by the experi mental procedure. So, information on successful experi mental hybridisation reinforces the need for the study of natural isolating mechanisms between the species involved, such as sex pheromone specificity, the circadian rhythms of sex pheromone release and male activity, and other aspects of possible species-specific mate recogni tion systems.…”

Natural hybridisation between Aphis grossulariae and Aphis schneideri: morphological evidence (Sternorrhyncha: Aphididae)

“…microsatellites and mitochondrial DNA techniques, see Hales et al, 1997;Sunnucks et al, 1997) would help to evaluate the degree of introgression between natural populations of these species. Natural isolating mecha nisms such as sex pheromone specificity, circadian rhythm of sex pheromone release, and other aspects of possible natural specific mate recognition system should be also studied Guldemond & Dixon, 1994;Thieme & Dixon, 1996). Morphological features of different morphs did not coincide within the same sample.…”

Physiological determinants of male mating performance in aphids (Hemiptera: Aphididae)

“…Females have a known circadian cycle of pheromone release from glands on the hind tibiae (see for example Guldemond & Dixon, 1994;Thieme & Dixon, 1996, Goldensaz & McNeil, 2003. The experiments described in the present paper were probably unaffected by pheromone attraction, since the aphids were confined in small containers which would become saturated with pheromone if it was released.…”