SURVIVAL, FECUNDITY, AND DEVELOPMENT OF DERMATOPHAGOIDES-FARINAE (ACARI, PYROGLYPHIDAE) AT FLUCTUATING RELATIVE-HUMIDITY

We determined the survival, development, and fecundity of Dermatophago ides farinae Hughes exposed to fluctuating daily regimes of hydrating and dehydrating relative humidity. Larva emerged from 84, 92, and 94% of eggs incubated at a regime of 2, 4, and 8 h at 75% RH and 22, 20, a nd 16 h at 0% RH, respectively. No emerging offspring completed the li fe cycle when exposed to the 2 and 4 h of moist air daily but 44 and 5 3% survived for 70 d in the larval or nymphal stages, respectively, an d these completed development to adults when subsequently held at a co nstant 75% RH. Given 8 h of moist air daily, 41% of emerging offspring completed the life cycle but development was 1.6 times longer compare d with development at a constant 75% RH. For all daily hydrating and d ehydrating regimes, a greater percentage of offspring became males tha n females. Overall, survival of immatures was remarkable at these dail y long periods of dehydrating conditions when a short period of hydrat ing moisture was provided. When exposed to a daily regime of 4 h of mo ist air (75% RH) and 20 h of dry air (0% RH), 84% of females survived 28 d and produced approximate to 1/3 of the number of eggs produced at constant 75% RH (control).