Effect of soil pH on fecundity, egg hatching and larval survival of phytophagous scarabs of Himachal Pradesh

摘要

The possible effects of soil pH on fecundity, egg hatching and larval survival o/Brahmina coriacea, Holotrichia longipennis and Anomala dimidiata were investigated in laboratory. Soils were amended with lime or aluminium sulphate to produce a range ofpH from 4.5-7.5. Fecundity was not influenced by soil pH in B. coriacea and A. dimidiata, but in H. longipennis, significantly higher (55.3 eggs/female) fecundity was recorded at pH 6.5. The soil pH did not influence the incubation period in any of the whitegrub species in the present study, however, egg survival was significantly affected in B. coriacea and A.. dimidiata in different soil pH levels. In case ofB. coriacea and A. dimidiata, higher egg survival (75.4% and 84.1%) was recorded at soil pH of7.5. Duration of instars (I - III) was not influenced by the soil pH, but larval survival was significantly affected in some species in some instars. In first instar, significant differences in larval survival were observed in B. coriacea and A. dimidiata. Maximum survival in both the species was recorded at pH 6.5. Almost similar trend was noticed in third instar grubs. Contrary to first and third instar, larval survival during second instar was significantly affected in H. longipennis, and maximum survival (77.5 %>) was recorded at pH 4.5.