Ecological studies on the two-spotted spider mite tetranychus urticae koch and its predators

الملخص EN

In the present study, the seasonal abundance of the two-spotted pider mite (TSSM), Tetranychus urticae Koch, and the relation with the naturally occurring predatory arthropods were investigated to explain variations in population numbers of the mite infecting the Castor bean crops.

During a one-year study on Castor bean trees, results showed that, the predominated predacious insects of spider mite TSSM were Stethorus gilvifrons Mulsant and Scolothrips longicornis Priesner.

The season alone and interacted with the presence of the predators were the limiting factors of TSSM abundance.

Abundance of TSSM and its predator S.

gilvifrons Mulsant, were the lowest in summer reaching its peak in spring.

On the other hand, the mean abundance of S.

longicornis Priesner was the highest in summer followed by spring, winter and autumn.

Studying the possible association between TSSM and its predator's results showed the presence of a significant negative correlation between TSSM and S.

longicornis while no correlation was found for S.

gilvifrons.

Moreover, the mean abundance of TSSM varied greatly among the different life stages of the predators.

In conclusion, the predators are essential for the biological control of TSSM.