Toxicity of some natural products against the adult stage of brown bark aphid, Pterochloroides persicae and whitefly, Bemisia tabaci under laboratory conditions.

A major study that needs to be carried out present different options alternative in the form of pesticides management. Three plants collected from locations throughout Yemen, namely Neem, indica; Sodom Apple, Calotropis procera and Africa Rue, Peganum harmala were assayed against adults’ stage of two sucking insects commonly present in Yemen environment. The brown bark aphid, Pterochloroides persicae (Cholodk) and the whitefly, Bemisia labaci (Genn.) are serious insects of some fruit and vegetable plants in Yemen. The bioassay based on exposure the adult of both insects to discs and tomato seedling, which were dipped in the plant extract. Mortalities were recorded at 24 and 48 hours aner treatment according to the LC₅₀ values. Neem extract showed the highest insecticidal activity against P. persicae followed by Sodom Apple and Hannala extracts after 48 hr of treatment. The LC₅₀ values were 64.94, 110.34 and 1880.89 ppm, whereas 24 hr LC₅₀ values were 95.36, 210.70 and 1900.11 ppm, respectively. It was found that B. tabaci adult was more susceptible than P. persicae. The extract of Neem gave the highest toxicity against the adult of B. labaci followed by Sodom Apple and African Rue at 24 and 48 hr. The LC₅₀ values were 52.48, %.86 and 155.42 ppm during the initial 24 hr exposure period, whereas 48 hr LC₅₀ were 8.93, 12.86 and 33.42 ppm, respectively. The present study suggests that natural agents, such as these suitable plant extracts, have the advantage of efficiency, highly selective, suitable for use in programs for integrated pest management, high mammalian safety, low costs and biodegradable to non-toxic products.