Interspecific Mating Effects on Locomotor Activity Rhythms and Refractoriness of Aedes albopictus (Diptera: Culicidae) Females

SIMPLE SUMMARY: The superiority of Aedes albopictus in larval resource competition was originally proposed as the cause of displacements of Aedes aegypti in the USA. However, satyrization, a form of reproductive interference, was later invoked as an alternative or complementary mechanism for the observed displacements of Aedes aegypti. This study tests the hypotheses that Ae. albopictus female activity is not altered by the presence of accessory gland extracts from conspecific and heterospecific males, and Ae. albopictus females remain receptive to conspecific males even after receiving accessory gland (AG) extracts from Ae. aegypti males. We performed experiments with a control group (females injected with saline), a group of females injected with accessory gland extracts of Ae. aegypti males and a group of females injected with accessory gland extracts of Ae. albopictus males and measured the locomotor activity and the ability of inseminated females to copulate with conspecific males. Females injected with conspecific and heterospecific extracts showed significant decreases in total and diurnal activity. Females injected with heterospecific extracts showed significant decreases in nocturnal activity. A total of 83% of females injected with heterospecific and 10% of females injected with conspecific extracts copulated with conspecific males. These results considered together with our previous report on effects of interspecific mating and cross-species injections of AG products on Ae. aegypti females, show consistent depressions of locomotor activities between species, but the loss of sexual receptivity only in Ae. aegypti. We propose that different male seminal fluid proteins control these activities. ABSTRACT: This study tests the hypotheses that the locomotor activity of Ae. albopictus females is not significantly altered by the presence of accessory gland (AG) extracts from conspecific and heterospecific males, and that Ae. albopictus females remain receptive to mating with conspecific males even after receiving AG of Ae. aegypti males. Virgin Ae. albopictus females were injected with saline (control group), AG extracts of Ae. aegypti males (aegMAG) or AG extracts of Ae. albopictus males (albMAG). Locomotor activity was evaluated under 12 h of light and 12 h of darkness at 25 °C. All live Ae. albopictus females were subsequently exposed to conspecific males for 48 h, and their spermathecae were dissected for the presence of sperm. Females injected with aegMAG and albMAG showed significant decreases in total, diurnal and diurnal without lights-on Period activities. Females injected with aegMAG showed significant decreases in nocturnal and nocturnal without lights-off period activities. Females injected with albMAG showed significant decreases in lights-off activity. A total of 83% of Ae. albopictus females injected with aegMAG and 10% of females injected with albMAG were inseminated by conspecific males. These results, coupled with our previous paper on MAG and interspecific mating effects on female Ae. aegypti, demonstrate contrasting outcomes on locomotor activities and loss of sexual receptivity, both conspecific and heterospecific MAGs capable of sterilizing virgin Ae. aegypti, but only conspecific MAGs sterilizing Ae. albopictus, whereas locomotor activities were depressed in females of both species after heterospecific and conspecific injections or treatments.