Adaptation to temperate climates: Evidence of photoperiodic-induced embryonic diapause in Aedes aegypti in South America

SYLVIA FISCHER; MONTINI, PEDRO; DE MAJO, MARÍA SOL; DI BATTISTA, CRISTIAN M.; LOETTI, VERÓNICA; CAMPOS, RAÚL E

Buenos Aires

Simposio; 8th International Symposium of the environmental physiology of ectotherms and plants; 2019

Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires

Diapause is a genetically regulateddevelopmental arrest in arthropods, which precedes the beginning of theunfavorable conditions in seasonally varying environments. In Aedes aegypti, the supposed inabilityof eggs to enter diapause has been used to explain the restriction of thisspecies to tropical and subtropical regions. However, the geographic range of Ae. aegypti is constantly expandingtowards temperate regions. Thus, the aim of the present study was to assess theability of Ae. aegypti individualsfrom a temperate region (Buenos Aires City, Argentina) to enter diapause. Tothis end, we exposed both the parental generation and the eggs to short-day(SD: 10L:14D) and long-day (LD: 14L:10D) photoperiods, and studied the temporalvariation in egg hatching. The experiment consisted of 28 treatmentcombinations of three factors: parental photoperiod (SD or LD), egg storagephotoperiod (SD or LD), and age of eggs (14, 28, 42, 56, 70, 91, and 112 days).The results showed a lower hatching response with the SD parental photoperiod,and a trend to higher hatching with longer egg storage time in all photoperiodtreatment combinations. The egg storage photoperiod showed no effect on egghatching. In both parental photoperiod treatments, egg replicates of most agesfrom different females showed a large variability, with some replicates withlowest hatching response and others with highest hatching response. Our resultsshow the ability of Ae. aegypti toinhibit egg hatching in response to a short-day photoperiod, which could allowthe further expansion of this species to regions with colder winters