No abstract

The parasitoid, Bracon hebetor Say (Hymenoptera: Braconidae) is a gregarious larval ectoparasitoid of several lepidopteran species. The reproductive biology of B. hebetor was studied on the larvae of its host, the sesame capsule borer Antigastra catalaunalis (Duponchel) (Lepidoptera: Pyralidae) under laboratory condition. The obtained results revealed that the total preimaginal period of B. hebetor on A. catalaunalis was significantly affected by ambient temperature being shortest at 35 o C (6.9 days) and longest (12.5 days) at 25ºC. Mating status had a significant effect on the ovipositional periods, fecundity and longevity being 154.9 and 105.8 eggs /female in mated and virgin females, respectively. Oviposition pattern for mated females showed a gradual increase then declined as females aged with only one maximum peak 12 days post emergence with greatest mean daily fecundity of 21.4 eggs/female/day. The supplemental food had a significant effect on adults of B. hebetor. Females of B. hebetor fed with pure honey together with the host larvae of A. catalaunalis parasitized a higher number of host (23.3 larvae) and laid a higher number of eggs per female (154.9 eggs). The numbers of paralyzed and parasitized hosts, number of daily laid eggs/host instar, longevity and percentages of emerged wasps were significantly affected by host instars. B. hebetor paralyzed all larval instars of A. catalaunalis but parasitized only third, fourth and fifth instar larvae. The fifth larval instar of A. catalaunalis was the most suitable instar for B. hebetor larval development than earlier instars as indicated by the highest total lifetime fecundity/female of 154.9 eggs and the highest percentage of emerged wasps of 93.5%.

Blaptostethus pallescens Poppius (Hemiptera: Anthocoridae) is a potential predator on mites and other insects in Maize, Mango and grain warehouses in Egypt. The indirect effect of four vegetable crops; bean (Phaseolus vulgaris), pepper (Capsicum annuum), eggplant (Solanum melongena) and cucumber (Cucumis sativus) as host-plants of the two spotted spider mite (TSSM) Tetranychus urticae Koch on the consumption rate and reproductive biology were studied at 30 ±1˚C and 60 ± 10% R.H. The obtained results revealed that the type of plant had a significant effect on the daily and overall prey consumption of all the nymphal instars and total developmental nymphal periods. The total predation rates of all nymphal instars of B. pallescens were higher with bean leaf plant (552.4 mites) than that of pepper, eggplant and cucumber leaf plants (520.5, 451.8 and 349.2 mites, respectively). The major portion of mortality during the nymphal stage occurred during the first instar in all tested host plants and the higher mortality was recorded when TSSM fed on mites fed cucumber plant, and the lower one was for mites fed on bean plant. The total number of consumed T. urticae nymphs by B. pallescens adult females was significantly different among the four host plants; being higher in bean plant leaves (301.9 mites) and lower on cucumber plant leaves (152.4 mites). Also, the total number of consumed T. urticae nymphs by B. pallescens adult males was significantly different among the four host plants; being higher in bean plant leaves (158.8 mites) and lower on cucumber plant leaves (105.3 mites). Significant differences in adult longevity among the different host plants were observed, the shortest lifetime for females was 17.7 days on cucumber, while the longest lifetime (22.3 days) was recorded with bean. The oviposition period was shortest on cucumber (10.5 days) and longest on bean (17.7days). Meanwhile, the greatest total lifetime fecundity (70.0 eggs/ female) was observed with bean plant, which was significantly higher than on cucumber plant (22.9 eggs/female). The success of B. pallescens as a biological control agent of TSSM seems to be strongly affected by the host plants on which the TSSM were fed on.

Stethorus gilvifrons (Mulsant), Orius albidipennis (Reuter) and Scolothrips longicornis Priesner are the key predators of Tetranychus urticae in Egypt. In this study, the intraguild predation (IGP) and cannibalism of adult females of these predators were studied under laboratory conditions. Data revealed that in the absence of extra guild prey (T. urticae), the adult females of IG predator S. gilvifrons consumed more larvae or nymphs of IG prey species than IG predators of O. albidipennis or S. longicornis. Females of S. gilvifrons showed significantly a higher predation rate on heterospecific young and old nymph instars of O. albidipennis than on S. longicornis. Interactions of adults S. gilvifrons and larvae or nymphs of O. albidipennis or S. longicornis were highly asymmetric or unidirectional predation always being the IG predator. S. gilvifrons had stronger intraguild predator than O. albidipennis or S. longicornis. Intraguild predation could be considered mutual between O. albidipennis and S. longicornis but there is neither predation nor egg deposition occurred on young or old larvae of S. gilvifrons. The IG predator O. albidipennis showed higher predation rate on S. longicornis than on conspecific nymphs. Whereas, S. longicornis showed high predation rate on conspecific larvae. Females of S. gilvifrons provided with conspecific or heterospecific young and old larvae or nymphs were able to lay eggs when fed on S. gilvifrons, O. albidipennis and S. longicornis. Also, O. albidipennis and S. longicornis laid eggs when fed on conspecific or heterospecific young and old larvae or nymphs except when fed on larvae of S. gilvifronsas IG prey. Obviously, the presence of T. urticae led to significant decrease in IGP.

Field studies were conducted on the seasonal incidence of sesame capsule borer, Antigastra catalaunalis (Duponchel) (Lepidoptera: Pyralidae) and parasitism rate of its ecto-larval parasitoid Bracon hebetor Say (Hymenoptera: Braconidae) in two successive seasons of 2012 and 2013 at Ismailia Governorate. Results indicated that A. catalaunalis larvae appeared in mid-June (15 day after sowing) then increased gradually till the end of crop maturation (2 nd or 3 rd week of September). The highest percentage of infested branches, leaves, flowers and capsules was 75, 72.5, 62.5 and 47.5% respectively in the first season and 70, 70, 55 and 45%, respectively in the second season. The incidence of A. catalaunalis larvae was higher in leaves or shoots than in flowers or capsules. Ambient temperature had a positive and significant correlation with percentage of infestation by A. catalaunalis as well as number of larvae per infested branches and flowers in the first season while it had non-significant negative correlation in the second season. The mean relative humidity percentages showed non-significant negative relationship with percentages of infestation or pest incidence during the two seasons. Rate of parasitism by B. hebetor varied among plant parts in which A. catalaunalis larvae were fed on during the two seasons; being higher in the second season. Maximum parasitism percentages were 28.3, 32.5, 26.3 and 20 % in infested branches, leaves, flowers and capsules in the first season and increased to 38.7, 41.7, 35.8 and 21%, respectively in the second one.