Magda Mofleh(1), AhmadMohammad(2)& MonzerHaloum(2)
(1). Scientific Agricultural Research Centre of Lattakia, Lattakia, Syria.
(2). Department of Plant Protection, Faculty of Agriculture, Tishreen University, Lattakia, Syria.
(Corresponding author: Dr. Magda MOFLEH: Scientific Agricultural Research Centre of Lattakia, Lattakia, Syria. E-mail:Magda.mofleh@yahoo.com).
Received: 24 / 09 / 2014 Accepted: 01 / 12 / 2014
Abstract:
The functional and numerical response of Stethorusv gilvifrons on different densities of adult prey Tetranychus urticae (Koch) was studied on leaf discs of Ricinus communis, at temperature 30±2ºC in laboratory. The predator consumed 4.04±0.79 adults/day, when prey density was 5 adults. The predator consumption increased with increasing prey density. At 50 preys the predator consumed 32.04±8.3 adults/day. Predation reached to 57.96±10.9 adults/day when prey density was 100 adults. So according Holling (1959) model of functional response, we put S. gilvifrons predator under the third type (type III). The increase of prey density caused increasing in egg numbers of predator. The predator female didn’t lay any eggs when prey density was 5 adults. The predator began laid eggs in few numbers 0.29±0.63 egg/day when fed on 10 prey adults/day, and these numbers of eggs laid by predator increased to 3.69±2.3 egg/day under prey density of 15 prey adult/day. the increase of egg numbers reached to 21.2±4.6 egg/day when prey density was 100 prey/day, so we noticed the predator oviposition increased with high prey density, and these increase caused by increase in predation efficiency and these lead to another kind of response called numerical response.
Key words: Tetranychus urticae, Stethorus gilvifrons, Functional response, Numerical response.