Bulletin of the National Research Centre (Aug 2019)
Effect of destruxin on the population reduction of green peach aphid Myzus persicae (Hemiptera: Aphididae) and the predator Coccinella undecimpunctata (Coleoptera: Coccinellidae) in tomato fields
Abstract
Abstract Background Destruxin is the toxin of some entomopathogenic fungi. Objective The efficiency of two destruxins, Destruxin A-760 and Destruxin A-724, was evaluated against the green peach aphids Myzus persicae (Sulzer) (Hemiptera: Aphididae) pests in tomato plants in two different climatic Governorates El-Sharkia and El Behira. Also, their safety levels to the predator Coccinella undecimpunctata L (Coleoptera: Coccinellidae) were studied under laboratory and field conditions. Materials and methods Two destruxin were applied on the target pests and its predators under laboratory and field conditions. Six aqueous concentrations of the two destruxin were prepared: 2.000–0.125 ppm. One day, adults of C. undecimpunctata and second instar nymphs of M. persicae were used for evaluation of the pathogenicity and efficacy of Destruxin A-760 and Destruxin A-724. This was accomplished by different techniques, a spray technique to evaluate contact effect and a feeding technique to evaluate oral toxicity. Results Results showed that, under laboratory conditions, LC50 values for Destruxin A-760 and Destruxin A-724 were 58 and 66 ppm, respectively against M. persicae. Under field conditions, the percentages of infested plants with M. persicae were significantly decreased after treatments with both Destruxin A-760 and Destruxin A-724 as compared with the corresponding controls. In Nobaryia, weights of tomato yield were 3158 and 3988 kg/feddan (F) when Destruxin A-760 and Destruxin A-724 whereas the control yielded 2169 kg/F in the corresponding controls, respectively. While the corresponding yield in EL Sharkia (Zagazig) were 3569 and 3599 kg/F following the same order as compared to 2169 ± 36.82 and 2000 ± 80.54 kg/ F, respectively in the control. The study showed that C. undecimpunctata exhibits relatively high and reasonable resistance to Destruxin A-760 and Destruxin A-724 at their highest lethal concentration (LC) (i.e., 44 ppm) for treated insects.
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