Quantitative trait loci determining autogeny and body size in the Asian tiger mosquito (Aedes albopictus)

The majority of mosquito species require a blood meal to stimulate vitellogenesis and subsequent oviposition (anautogeny), but some autogenous individuals complete their first ovarian cycle without a blood meal. Autogeny may be facultative or obligatory. In this study, we selected for an autogenous strain in the Asian tiger mosquito Aedes albopictus and examined an F-1 intercross population for quantitative trait loci (QTL) determining the autogeny trait as well as wing length as a proxy for body size. Using composite interval mapping, we identified four QTL for each trait and observed considerable overlap in genome positions between each QTL for autogeny (follicle size) and wing length. Most QTL were minor in magnitude, individually explaining < 10% of the phenotypic variation. Alleles from the autogenous parent generally showed a dominance or overdominance effect on both phenotypes. Strong genetic and phenotypic correlations indicate that autogeny and wing length are determined by up to four clusters of tightly linked genes or the potential pleiotropic effects of single genes. Although females from the autogenous strain produced approximately fivefold more eggs following a blood meal than through autogeny, we suggest that the maintenance of alleles for autogeny in natural populations is likely due to balancing selection. Autogeny should be favored under conditions of limited host availability for blood feeding or increased defensive behavior by the host and adequate larval nutrition. Correlation between autogeny and body size may reflect an increased ability for larger females to accumulate sufficient nutrient reserves to support oogenesis without the requirement for a blood meal.