Combined effect of some bio agents against the grasshopper Hetiracris littoralis under semi-field condition

Combined Effect of Some Bio-Agents  Against the Grasshopper,

Hetiracris littoralis Under Semi-Field Condition

By

Aziza Sharaby^1*, Mohamed A. Gesraha¹, Sayed A. Montasser², Youssef A. Mahmoud¹, Sobhi A. Ibrahim¹

1- Department of  Pests & Plant Protection, National Research Center, Dokki, Cairo, EGYPT

2- Faculty of Agriculture, Al- Azhar University, Cairo, EGYPT

* Corresponding author: sharaby.aziza@yahoo.com

 Abstract:

 LC₅₀ of the alchoholic-80% extract of Euphorbia pulcharrima (0.714%),(Ephorbiaceae) essential oil of Garlic plant  Allium sativum (0.067%)(Liliaceae) and entomopathogenic nematodes (EPN_s)of  Steinernima carpocapsae (Stienernematidae) and Heterorhabditis bacteriophora(Heterorahbditidae ) (500 IJs/ml), were tested for their solely and/or combined toxic effects and for their effects on some biological aspects against the grasshopper, Heteracris littoralis(Orthoptera: acrididae) 1^st instar nymphs under semi-field condition.H. littoralis isconsidered one of the most harmful pests to different cultivated crops in Egypt.   The joint action of the mixture of the most effective extract (E. pulchrrima) and oil (Garlic oil) exhibit an antagonistic effect with co-toxicity index of (–24), despite the increase the proportion of death in the mixture for all the tested groups the type of interaction were antagonism, all the tested materials had variable mode of action which resulted in significantly antagonistic effects. Co-toxicity action of the mixture have been based on the physical and chemical properties of the compound. Reviewing the obtained results, it can be concluded that the efficiency of the different tested bio-agents material mixture against the 1^st instar nymphs of H. littoralis varied tremendously according to the type of compounds of the tested mixture. Euphorbia 80% methanol extract and Garlic oil may used separately or in combination as alternatives safe tools against H. littoralis grasshopper. The effect of volatile oil and the plant extract may be attributed to one or more of the following: fumigant, contact or poisoning effect and may due to the presence of some chemical groups in their structure. Semi-field experiments cleared that nematodes in combination with the oil or extract increased the mortality  percentage. The combination mixture of extract, oil and nematode significantly affected development, reproduction and life cycle of H. littoralis. Lethal effect varied with regard to the nematode species. Semi-field experiment of the plant extract, plant oil and their mixture revealed some changes on the biological aspects, an increase in the nymphal period, pre-oviposition, oviposition and post-oviposition periods. There is vigorous decrease in the female fecundity and fertility. The control of the insect by nematode and sub-lethal dose of plant extract or plant volatile oil as biological control may enhance their lethal effect on insect pest when applied simultaneously. Plant products played as catalytic agents and increased the susceptibility of pests to infection by nematode. Combination mixture of the tested bio-agent could be considered as possible means for use in programs of integrated pest management of H. littoralis grasshopper.