واکنش تابعی ویژه ی مرحله ای کفشدوزک Stethorus gilvifrons و سن شکارگر Orius albidipennis با تغذیه از Tetranychus urticae در شرایط آزمایشگاهی

The two-spotted spider mite, Tetranychus urticae Koch, is one of the most economically important pests on a wide range of crops around the world. The ladybird Stethorus gilvifrons (Mulsant) (Col., Coccinellidae) and the bug Orius albidipennis Rueter (Hem., Anthocoridae) are two important acarophagous predators in Iran. Functional response of different stages of Stethorus gilvifrons and Orius albidipennis to eggs, protonymphs and females of T. urticae were evaluated under laboratory conditions (27±1°C, 65±5% RH and 16L/8D h photoperiod). Functional response type was determined by a logistic regression model. The Rogers model was used to estimate searching efficiency (a) and handling time (Th). The results indicated that the functional response of different stages of two predators were type III on T. urticae eggs and type II on T. urticae prototonymph and females. The shortest handling time (Th) of all stages of both predators were observed on eggs followed by protonymphs and females of T. urticae. The highest and the lowest attack rate (a) of S. gilvifrons and O. albidipennis were observed by adults, first instar nymph and larvae respectively. The maximum attack rate (T/Th) was observed by females of both predators that estimated to be 153.5, 114.4 and 76.07 on egg, protonymph and female of T. urticae for S. gilvifrons, and 134.1, 91 and 55.3 for O. albidipennis respectively. The mean attack rate of S. gilvifrons females were 2.12, 3.06 and 6.74 times as much as the first instar larvae and that of the O. albidipennis females were 2.43, 5.24 and 12.14 times as much as the first instar nymphs by feeding on egg, protonymph and female T. urticae, respectively. The handling time (Th) of S. gilvifrons adults were shorter than that of O. albidipennis at all stages of the prey. The results also showed that both predators consumed more eggs than nymph or female of T. urticae. According to our results, both predators exhibited suitable efficacy on different stages of T. urticae, although S. gilvifrons was more effective than the other predator in laboratory conditions due to higher consumption rate, shorter handling time and higher searching efficiency.