Evaluation of some plant extracts and entomopathogenic fungi against the two-spotted spider mite Tetranychus urticae (Acari: Tetranychyidae) and some associated predators

Abstract

Two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychyidae) is a polyphagous plant mite pest causing major economic  losses. Avoiding the extensive application of chemical pesticides, which had many hazards to human health and the environment and to  obtain satisfactory alternatives to pesticides to combat the, two plant extracts Portulaca oleracea L. (Family: Portulacaceae) and Lepidium  sativum L. (Family: Brassicaceae) and two isolates of entomopathogenic fungi Beauveria bassiana (Bals) Vuill (Family: Cordycipitaceae)  and Paecilomyces lilacinus (Thom) (Family: Ophiocordycipitaceae), were tested on in the laboratory; a side effects of highly virulent tested material was examined on some of the predators, Phytoseiulus persimilis Athias-Henriot, Neoseiulus californicus (McGregor), Neoseiulus  bicaudus (Wainstein) (Acari: Phytoseiidae) and Orius albidipennis (Hemiptera: Anthocoridae). Mortality rates for T. urtice ranged between  21-91% for P. oleracea and 24-80% for L. sativum, while for the two fungi isolates, Beauveria and Paecilomyces, ranged between 38.2 - 74.5%  and 31.3 - 49.1% on T. urtice, respectively. The side effects of the plant extract ranged between 24-35% on predatory mites and  3.85% on predatory insects. Whereas fungi effect was less than 30 % for all predators. Due to its effect on T. urticae and minimal effect on  O. albidipennis, both proposed methods could be used to control the pest mite alone or incompatible with the predatory insect in joint programs. The detrimental effect of the tested material on predatory mite survival and progeny indicates the need for further studies to  develop other strategies that combine these natural control agents.