Effect of temperature on reproductive parameters of Aphidius colemani and Aphidius matricariae (Hymenoptera: Braconidae) on Aphis gossypii (Hemiptera: Aphididae) in laboratory conditions

The aphid parasitoids, Aphidius colemnai Viereck and A. matricariae (Haliday) (Hymenoptera: Braconidae: Aphidiinae) have high potential as the most effective biological control agents for controlling the cotton aphid Aphis gossypii Glover (Hemiptera: Aphididae). In this investigation, the effect of five constant temperatures (10, 15, 20, 25 and 30 °C) on the reproductive parameters of the parasitoids was studied at 65 ± 5 % relative humidity and a photoperiod of 16L: 8D hours. The newly laid (one- day old) eggs were reared on third instar nymphs of cotton aphid, and the pupal and adult stages of the parasitoids were recorded daily, until the last individual was found dead. The experiments were carried out with 15 replications at each temperature. The results revealed that the gross fecundity and fertility rates were significantly different at all tested temperatures for both species (P < 0.05). The highest value for the mean fertile eggs per day were recorded at 25 °C and 30 °C for A. matricariae and A. colemani, respetively. The results of this research can be used for establishing integrated pest management (IPM) strategies against A. gossypii in cucumber greenhouses.