THE EFFECT OF CONSTANT-TEMPERATURE AND HUMIDITY ON THE DEVELOPMENT, LONGEVITY AND PRODUCTIVITY OF AHASVERUS-ADVENA (WALTL,) (COLEOPTERA, SILVANIDAE)

The development and productivity of Ahasverus advena (Waltl.) was stud ied on kibbled wheat at humidities ranging from 65 to 90% r.h,, in com bination with temperatures varying from 15 to 35 degrees C. Longevity was also investigated between 10 and 25 degrees C. At 70% r,h. complet e development took 67, 58 and 48 days at 20, 22.5 and 25 degrees C, re spectively, while cumulative mortality was 94, 52 and 65%. At 90% r,h. complete development took 70, 46, 31, 26, 21, 16 and 22 days at 17.5, 20, 22.5, 25, 27.5, 30 and 32.5 degrees C, while cumulative mortality was 94, 68, 63, 44, 58, 45 and 57%, At 65% r.h, longevity increased f rom 18 days at 10 degrees C to 63 days at 15 degrees C and then decrea sed to 35 days at 25 degrees C. At 90% r.h. the mean longevity increas ed from 69 days at 10 degrees C to 267 days at 15 degrees C and then d eclined to 99 days at 25 degrees C, A, advena was not productive at an y humidity at 15 degrees C, nor at 65% r.h. at temperatures below 25 d egrees C. Productivity also failed at 70% r,h,, at temperatures below 20 degrees C, However, at 80 and 90% r,h. productivity was markedly hi gh at 17.5, 20 and 25 degrees C and 50 adults produced a mean of 235 p rogeny in 3 weeks at 90% r,h,, 25 degrees C. Although the species cann ot develop under the cool, dry conditions of temperate storage, adults can survive for long periods under these conditions. On farms it may develop in manure heaps and mouldy straw bales and fly to grain stores when the weather is warm. Crown copyright 1996 Published by Elsevier Science Ltd