Toxicological and Biological Effects of Juvenile Hormone Mimic (JHM) Pyriproxyfen Against the Two Spotted Spider Mite, Tetranychus urticae Koch (Acari: Tetranychidae)

Document Type : Original research articles

Authors

Plant protection Research Institute, A.R.C, Dokki, Giza, Egypt.

Abstract

The present investigation was carried out to study the effect of Juvenile Hormone Mimic (JHM), Pyriproxyfen 10% EC on toxicological and biological aspects of the two spotted spider mite, Tetranychus urticae Koch under laboratory conditions. The effects of Pyriproxyfen on mortality, life cycle, duration period, adult longevity, ovipositional period and female fecundity were evaluated. Results indicated that the candidate compound exhibited direct contact toxicity against all the different developmental stages of T. urticae, but protonymphs were more susceptible than adult females. The LC50's were 4.21 and 4.36 ppm after 72 hr. post exposure for protonymphs and females, respectively. Also it had contact ovicidal activity influenced by egg age. 48-72 hr. eggs were significantly more sensitive than eggs of the other ages. According to LC50 values LC50's were 117.07, 7.95 and 2.91ppm for the three tested ages (0-24 hr, 24-48 hr and 48-72 hr old), respectively. Also, all the tested concentrations prolongated the incubation, larval, protonymphal and deutonymphal periods, but the maximum conc. level (10 ppm) produced the highest increase. Also, the longevity of males and females were increased, the highest increase was observed with 10 ppm, it produced 23.42 days/♀ and 18.5 days/♂ compared with 15.59 days/♀ and 15.92 days/♂ in the control. On the otherhand, oviposition periods were also influenced as concentration dependant response. The mean number of laid eggs/♀ were highly decreased as conc. increased, the highest decrease was observed with T. urticae females treated with conc. 10 ppm, it gave 14.17 eggs/♀ compared with 124 eggs/♀ in untreated females. Results suggest that JHM, pyriproxyfen could be a good alternative and interesting component in Integrated Pest Management (IPM) for controlling TSSM, T. urticae and minimizing the usage of conventional pesticides.

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