Journal of Environmental Biology

Importance of plant extract formulations in managing desert locust Schistocerca gregaria

Sayed M. Rawi¹*, Mansour A. Al-Hazmi¹, Torkey H. M.² and Kamel A. K.^1,3

¹Faculty of Sciences and Arts, Khulais, King Abdulaziz University, Jeddah, 21921, KSA

²Central Laboratory of Pesticides, Agricultural Research Center, 12613, Egypt

³Department of Botany, Faculty of Science, Suez Canal University, Ismailia, 41522, Egypt

*Corresponding Author E-mail: rawisayed@gmail.com

Publication Data

Paper received:

15 September 2014

Revised received:

29 April 2015

Re-revised received:

18 October 2015

Accepted:

21 October 2015

Abstract

Toxicity of n-hexane and methylene chloride extracts of Azadirachta indica, Citrullus colocynthis, Ammi majus and Mentha microphylla was evaluated against the newly moulted 2nd instar nymph of desert locust Schistiocerca gregaria (Forsk). Leaves dip bioassays were used to obtain concentration-mortality data. Treatments of nymphs for 7 and 14 days, leading to calculation of LC₅₀ and LC₉₀ values. A wide range in LC₅₀ and LC₉₀ values was exhibited among the tested extracts. After 14 days of feeding, the product of A. majus with methylene chloride solvent was most active against 2^nd instar nymph (LC₅₀=25.13 mg ml^-1), followed by C. colocynthis (LC₅₀=39.92 mg ml^-1), A. majus (LC₅₀=66.78 mg ml^-1) and M. microphylla (LC₅₀=70.35 mg ml^-1). Formulated extracts were investigated by two non-ionic surfactants and two blended emulsifiers. After formulations with sodium sulphonate as emulsifier, methylene chloride extracts of A. indica substantially increased nymphal mortality, reduced nymphal weight, exhibited adverse morphogenic effects and raised nymph duration period. Moreover, prolonged exposure to 100 mg ml^-1 of formulated extracts of A. indicia and C. colocynthis decreased effect on hemolymph total protein, total lipids and glucose contents as well as, on ALAT activity of the studied nymph. These results document the potential of botanical formulations of A. indicia and C. colocynthis with sodium sulphonate as emulsifier may prove to be a probable candidate for development of biopesticides to control desert locust.    

 Key words

Formulation, Plant extract, Schistocerca gregaria, Toxicity

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