Effect of some biological and biochemical control agents against certain squash pests

Abstract

Predatory mite species (Amblyseius californicus McGregor and Phytoseiulus persimilis Athias-Henriot) and two chemical compounds (Vertimic and Denatol) were used to control the phytophagous mite, Tetranychus urticae Koch and phytophagous insect species: Thrips tabaci Lind., Aphis gossypii (Glover) and Bemisia tabaci (Gennadius) on three squash cultivars (American, Hitec and Eskandarani) in Qalubiea Governorate. The results of control pest experiments on the three tested squash cultivars showed that the reduction percentage of the spider mite populations was significantly different among treatments (F 3,108 = 12.29; P < 0.001). Generally, the biological control of the spider mite by the predatory mite species was significantly better (as the population reduction of the spider mites was 93.02% for A. californicus treatment and 92.15% for P. persimilis) than the reduction under the chemical control which was 75.42% for Vertimic treatment and 71.82% for Denatol compared with control treatment. On the contrary, the reduction percentage of the population of the three insect species by the chemical control on the squash cultivars was significantly higher than the biological control (F 1,342 = 28.16; P < 0.001). The reduction of the insect species under chemical control was 25.14% as an average, while it was 11.53% as an average in case of biological control treatments. These experiments suggested that releasing A. californicus and P. persimilis is more favourable strategy for suppression of spider mites than chemical control.