Effect of neem products on the survival and reproduction of Egyptian Heterorhabditis bacteriophora used against lepidopterous insect pests [electronic resource].

Includes references.

The effect of neem products on the survival rate of an Egyptian entomopathogenic nematode (EPN), Heterorhabditis bacteriophora (EBN34) was tested, Two commercial products of NeemAzal T/S (1 % Azadirachtin) and neem powder (NP- 30% Azadirachtin) were used at different concentrations. The suspension of both (neem products and nematodes) was tested against last instar larvae of Galleria mellonella and second instar larvae of the Egyptian cotton leafworm, Spodoptera littoralis. The infective juveniles (IJs) stage of EBN34 were not affected when added to low concentrations of neem products. Meanwhile, high concentrations of neem products significantly affected the survival of nematode infective juveniles. whereas, the survived Us didn't cause significant mortality of G, mellonella larvae but nematode reproduction was affected significantly. The neem liquid commercial product (NeemAzal T/S) resulted in 22.0 % mortality in EBN34 juvenils at 100 IJs/ml when contacted directly by 1.0 % of NTS for 24 hours. When nematodes exposed to NTS for longer periods up to 48 and 96 hours, the mortality percentage increased directely to 40 and 56 rescpectively. Toxicity has increased gradually according to the increase in product concentration and exposure period at different of nematodes concentrations. Treated nematodes with NTS caused more than 80 % mortality in last instar larvae of G, mellonella, meanwhile treatment of the juveniles with NP resulted in ca 50% mortalitry. Reproduction of nematodes was highly affected as a result of treatment with neem products in comparison with the control. Using higher concentrations of neem products with nematodes (500 IJs/larva) resulted in 40-50% mortality of the juveniles and flactuated mortality percentage of Galleria larvae. Minimum larval mortality (14 %) was recorded after two days of feeding period on treated plant leaves with 0.125 % NTS at both nematode concentrations, while the maximum (96 % mortality) was found when 1.0 % NP was added at the same feeding period and juvenile concentrations. Mean number of emerged juveniles from dead larvae was low when high concentrations of both neem products was used than low concentrations. Increasing feeding period of larvae on treated leaves to 4 and 6 days decreased the propability of juvenile emergence due to the increase in larval mortality at both juvenile concentrations and the increasing levels of the tested neem products, especially in case ofneem powder. Key Words: Entomopathogenic nematodes, Galleria mellonella, Heterorhabditis bacteriophora, lepidopterous pests, NeemAzal TIS (NTS), reproduction, Spodoptera littoralis, survival.

Summary in Arabic.

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