Development, life table and thermal requirement of Tyrophagus putrescentiae (Astigmata : Acaridae) on mushrooms

The synanthropic mould mite, Tyrophagus putrescentiae infests various stored products, plant seeds and mushroom beds. Its biology was studied under controlled laboratory conditions at 10, 15, 20, 25, and 30 degrees C, 70% r.h. and a photoperiod of 16:8 (L:D) h when reared on button mushroom, Agaricus bisporus and oyster mushroom, Pleurotus ostreatus. Tyrophagus putrescentiae had a significantly shorter developmental time at 25 degrees C when reared on button mushroom compared with oyster mushroom and this time decreased with increasing temperature. The pre-oviposition period was not influenced by the species of mushroom, but the other reproductive periods showed significant changes and female longevity was influenced by food type. The sex ratio of the offspring (female/male) and female percentage were 1.16% and 53.7%, respectively. When reared on button mushroom at 25 degrees C, the net reproductive rate (R-0) for T. putrescentiae was 90.13 and the intrinsic rate of increase (r(m)) was 0.196 which were significantly different from the 18.97 and 0.122, respectively, when reared on oyster mushroom. The doubling times were 3.74 and 5.62 days for the two mushroom types, respectively. The developmental thresholds for eggs, larvae, protonymphs and tritonymphs were 8.38, 8.01, 7.51 and 10. 12 degrees C, respectively, and the thermal unit (degree-days) for all immature stages was 250.62 degrees C. Developmental thresholds of the various stages were significantly different. (C) 2006 Elsevier Ltd. All rights reserved.