Oviposition Behavior of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) from Panama Under Experimental L4-Larval Co-Occurrence Scenarios

While a great deal of research has been conducted to identify the biotic mechanisms influencing the co-occurrence of aquatic <i>Ae. aegypti</i> and <i>Ae. albopictus</i> mosquitoes, including inter-specific larval competition and mating interference, few studies have been completed to investigate their oviposition behaviors under co-occurrence scenarios. Herein, we performed three experiments to understand the influence of conspecific and heterospecific L4-larvae presence in oviposition by antagonist <i>Aedes</i> spp. mosquitoes. We compared egg counts of <i>Ae. aegypti</i> and <i>Ae. albopictus</i> in cups with water and conspecific or heterospecific larvae (either present or removed), or no larvae as control. In the first experiment, we used small cages; in the second experiment, we used larger cages increasing the number of treatment replicates per cage; and in the third experiment, we removed larvae before allowing gravid females to oviposit. In experiments 1 and 2, <i>Ae. aegypti</i> laid more eggs in conspecific cups, while <i>Ae. albopictus</i> distributed eggs evenly between conspecific and heterospecific cups, and both species laid fewer eggs in controls. In these experiments, more eggs were laid during the first 24 h. In experiment 3, both species laid more eggs in conspecific larvae-conditioned water as compared to controls in the first 24 h; however, in <i>Ae. Aegypti</i>, this inclination was lost with time. Our results suggest that co-occurrence of <i>Ae. aegypti</i> and <i>Ae. albopictus</i> may be explained by <i>Ae. aegypti</i>'s ability to avoid oviposition in habitats colonized by heterospecific L4-larvae. Yet chemical cues in conspecific L4-larvae-conditioned water were insufficient to replicate this behavior, and therefore, additional cues may be involved.