BIOLOGICAL ASPECTS AND THERMAL REQUIREMENTS OF THE BIRD CHERRY-OAT APHID, Rhopalosiphum padi (LINNAEUS), REARED ON WHEAT SEEDLINGS

Abstract

The bird cherry-oat aphid, Rhopalosiphum padi (Linnaeus) was studied at 15, 20 and 25 o C constant temperatures. Wheat seedlings were offered for feeding and maintaining the aphid, R. padi using the Punctured Ependorf Tube Technique. R. padi showed the longest life cycle duration at 15 o C as 12.77±1.71days. This duration decreased to 8. The lower developmental threshold (t 0) for the R. padi nymphal instars; first, second, third and fourth were 2.216, 6.958, 3.432 and 0.164 o C, respectively. The estimated t 0 values for the life-cycle and generation time were 3.537 and 3.976 o C, respectively. The thermal requirements (K) for each nymphal instar; first, second, third and fourth were, life-cycle and generation time were 45.972, 23.439, 30.973, 47.147, 142.566 and 154.155 dgree-days units, respectively.