Life table studies of Earias vittella (Fabricius) on different hosts in the Insect Biotech Laboratory, Department of Entomology, Dr PDKV Akola, revealed that survival (lx) of immature stages of E. vittella on different hosts was 0.65 on okra, 0.56 on cotton, 0.54 on semi-synthetic diet and 0.51 on mesta. The net reproductive rate (Ro), at the end of each generation, of E. vittella was 81.91 on okra, 56.70 on cotton, 53.02 on semi-synthetic diet and 36.63 on mesta (Hibiscus cannabinus L.). The net reproductive rate (Ro) followed the same order as the survival rate (lx) on the different hosts. The innate capacity for increase in numbers (rm) ranged between 0.0888 and 0.1334 females/female/day. In descending order, the rm values on different hosts were okra (0.1334), cotton (0.1111), semi-synthetic diet (0.1029) and mesta (0.0888).

Laboratory experiments were conducted to investigate the effect of diet on the biology and prédation capacity of the phytoseiid mite Amblyseius zaheri Yousef & El-Brolossy. The predatory mite was able to develop and reproduce when fed on nymphs of the twospotted spider mite Tetranychus urticae Koch, nymphs of the citrus brown mite Eutetranychus orientalis Klein, motile stages of the eriophyid mite Eriophyes dioscoridis Soliman & Abou-Awad, eggs of the scale insect Parlatorio ziziphus Lucas, nymphs of the whitefly Bemisia tabaci (Genn.) and pollen grains of date palm, Phoenix dactylifera. The predatory mite's development was fastest on a diet of nymphs of Er. dioscoridis. All of the diets led to a female-biased progeny, which was most pronounced in predators fed on date palm pollen. The results are discussed in light of the biological control capacity of the phytoseiid mite.

The demographic statistics of the ladybird Exochomus flaviventris Mader (Coleoptera: Coccinellidae) were investigated under laboratory conditions on the cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Homoptera: Pseudococcidae), reared on four host plants with different levels of antibiotic resistance to the mealybug: two cassava (Manihot esculenta Crantz, Euphorbiaceae) varieties, Incoza and Zanaga, Faux-Caoutchouc (FC) (hybrid of M. esculenta × M. glaziovii Muel. Arg.) and water weed (Talinum triangulare Jack, Portulacacae). Preimaginal mortality, mean oviposition time and total fecundity of female ladybirds were strongly affected by the host plant even though there was no linkage with antibiotic resistance. The net reproduction rates R0 of the predator were 1.5,1.7 and 2.4 times higher on Zanaga than on water weed, Incoza and FC respectively, and the generation time (T) was significantly longer on Zanaga than on the other three plants. The intrinsic rate of increase rm was not modified by the antibiotic resistance of the host plants. With the two cassava varieties, Incoza and Zanaga, it was found that antibiosis significantly affected the life history parameters of the ladybird without modifying its fitness, and provided better cassava mealybug control.

The immature stages of the predaceous mite Typhlodromus talbii Athias-Henriot are described. The mite was reared on different prey species and pollen in the laboratory, and its developmental parameters calculated. Tydeus californicus (Banks) was found to be the most suitable and nourishing diet, giving a shorter life cycle and higher female fecundity (8.8 days and 33.4 eggs respectively), than the scale insect Coccus acuminatum (Gennadius) (10.0 days and 24.8 eggs respectively) at 25 °C. Other associates of Typ. talbii, the eriophyid Cesaberoptus kenyae Keifer, the tetranychid Oligonychus mangiferus (R. & S.) as well as date palm and castor oil pollen, were unsuitable diet. When reared on moving stages of Tyd. californicus (Banks) at 70 ± 5 % RH, 16:8 (L:D) h photoperiod and temperatures of 15,20,25,28,30,32 and 35 °C, the total developmental time of Typ. talbii averaged 21.3, 12.4, 8.8, 7.6, 7.1, 5.8 and 11.6 days respectively. The intrinsic rate of natural increase (rm) and the net reproduction (Ro) reached maximum values of 0.299 individuals per female per day and 28.06 times respectively, at 32 °C.

The development, life table and intrinsic rate of natural increase of the reduviid predator Rhynocoris fuscipes (Fabricius) on Spodoptera litura Fab., Earias vittella Fab. and Corcyra cephalonica Stainton under laboratory conditions were constructed. Fecundity, longevity and minimum developmental period of the predator were dependent on the prey diet and decreased in the order: S. litura, E. vittella and C. cephalonica. The mean number of female progeny produced over the entire period (the gross reproductive rate) was 43.0, 37.5 and 32.5 on S. litura, E. vittella and C. cephalonica respectively. The net reproductive rate (Ro), intrinsic rate of increase (rc) and weekly multiplication rate were also highest on S. litura followed by E. vittella and C. cephalonica.

In the present work, influence of food plants on different life table parameters of the parasitoid Trioxys indicus Subba Rao and Sharma was studied as affected through its host Aphis gossypii Glover. Age-specific survival of T. indicus on aphids bred on Lagenaria vulgaris was greater (7 days) than on Luff a cylindrica and Cucurbita maxima (4 days). The net fecundity rate, total reproductive period, intrinsic rate of natural increase, intrinsic rate of total fecundity and weekly multiplication rate of T. indicus fed on L. vulgaris was higher than on other cucurbit food plants. Doubling time of the parasitoid fed on L. vulgaris was lower than on other food plants, whereas the mean generation time of the parasitoid on L. vulgaris was slightly higher than on L. cylindrica but lower than on Cajanus cajan and C. maxima. All these measurements (considered indices of fitness of the entomophages) indicated that population growth pattern of T. indicus fed on L. vulgaris is faster than those fed on other food plants.