Distribution of chigger mites (Acari: Trombiculidae) over hosts, parasitopes, collection localities, and seasons in northern Iran.

We studied the distribution of chigger mite species over mammal hosts, attachment sites on the host body, habitats, and seasons in Iran. The study was based on 2155 specimens of 36 chigger species collected from 10 species of Muridae, Cricetidae, and Soricidae across six provinces of northern Iran. A high level of mixed infestation by chiggers was recorded-76% of hosts parasitized by chiggers were infested by more than one (2-8) species. Statistically significant differences in the preference for anterior and posterior parts of the host body were found. Three species-Neotrombicula lubrica, N. delijani, and Cheladonta firdousii-preferred the posterior part of the host body; 12 species were characterized by the occurrence in the anterior part and differed from one another by the frequency of presence in the posterior part. One species, Hirsutiella alpina, was found only in the anterior part of the host body (inside the ears of rodents). The most diverse chigger fauna was on the fringe of Golestan National Park (species richness = 21, Shannon-Wiener index = 2.823). The chigger fauna of the high-mountain localities on the Alborz Range was the least diverse (species richness = 16, Shannon-Wiener index = 2.439). The seasonal aspect of activity was evident for Neotrombicula elegans, which exposed the autumn-winter period of the occurrence on hosts, and N. vernalis, with the winter-spring peak of abundance.

Olfactory response of Phytoseiulus persimilis (Acari: Phytoseiidae) to untreated and Beauveria bassiana-treated Tetranychus urticae (Acari: Tetranychidae).

Determination of attraction and avoidance behavior of predators is important in concomitant use of multiple natural enemies to control a pest. The olfactory response of the predatory mite Phytoseiulus persimilis was studied to odors related to Tetranychus urticae adults infected by Beauveria bassiana DEBI008 in 0, 24, 48 and 72 h intervals, both in absence and in presence of plants. In plant-present experiments, P. persimilis attraction was neither towards adults of T. urticae infected by 0.02 % Tween 80 (as control), nor to the ones infected by B. bassiana for 0 or 24 h, whereas significant attraction towards the control was observed when tested against T. urticae infected by B. bassiana for 48 or 72 h. In absence of plants, P. persimilis displayed significant avoidance of T. urticae infected by B. bassiana for 48 or 72 h, when their alternative option was 0.02 % Tween 80-infected T. urticae adults. These results indicate that P. persimilis can recognize the presence of B. bassiana and that the predator avoids the fungus. This suggests that the two natural enemy species can be used together in biological control programmes.

Olfactory response of the predator Zetzellia mali to a prey patch occupied by a conspecific predator.

While searching for food, predators may use volatiles associated with their prey, but also with their competitors for prey. This was tested for the case of Zetzellia mali (Ewing) (Acari: Stigmaeidae), an important predator of the hawthorn spider mite, Amphitetranychus viennensis (Zacher) (Acari: Tetranychidae), in black-cherry orchards in Baraghan, Iran. Using a Y-tube olfactometer, the response of this predatory mite was tested to odour from black-cherry leaves with a conspecific female predatory mite, either with or without a female of the hawthorn spider mite when the alternative odour came from black-cherry leaves with the hawthorn spider mite only. Female predators avoided odours from leaves with both a hawthorn spider mite and a conspecific predator, as well as leaves with a conspecific predator only. We discuss whether avoidance emerges in response to cues from the competitor/predator, the herbivore/prey or the herbivore-damaged plant.