INFLUENCE OF HOST PLANT ON LIFE AND FERTILITY TABLES FOR Scymnus coccivora AYYAR.

Abstract

Studies on the life and fertility tables of the coccinellid predator, Scymnus coccivora Ayyar. were conducted to estimate some of its biological aspects on four different host plants (hibiscus, Sprouted potatoes, Grape and Japanese pumpkins) infested with hibiscus mealybug, Maconellicoccus hirsutus (Green). The stage duration, survival rate, the net reproductive rate and the intrinsic rate of natural increase were examined. The developmental periods were significantly affected by host plant. The mean duration of the larval stage on hibiscus, Sprouted potatoes, Grape and Japanese pumpkins were 10.51, 11.65, 11.82 and 11.86 days, respectively. The total developmental period of immature stages lasted by 19.88, 21.6, 21.9 and 20.28, respectively. The stage specific survival of life table data indicated that the mortality factor operated mainly during larval stage. The highest larval survival of 78.9 ± 7.0% was recorded on potatoes followed by 73.8 ± 12.0% on pumpkin and 64.4 ± 5.1 % on hibiscus; while the least (61.1 ± 3.8 %) occurred on grape. The fertility of S. coccivorafemales was relatively high on potatoes followed by hibiscus, grape and pumpkin. The net reproductive rate was 47.81 ± 17.09, 35.84 ± 2.76, 22,70 ± 4.64 and 22.55±4.53 females/ female, respectively. The intrinsic rate of increase (rm) was 0.097 ± 0.005, 0.088 ± 0.015, 0.083 ± 0.005and 0.082 ± 0.006 females/ female/ day, on potatoes, hibiscus, grape and pumpkin, respectively. In the same order, the time of generation was 39.39 ±3.25, 41.32 ± 6.35 37.69 ± 2.49 and 38.06 ± 5.10 days, respectively.