Development and Reproduction of a Population ofEretmocerus eremicus(Hymenoptera: Aphelinidae) onBemisia argentifolii(Homoptera: Aleyrodidae)

Abstract

Although the aphelinid parasitoid E7'etmocertlo' erem.iclIs Rose & Zolnerowich is the most abundant naturally occurring parasitoid of Bemisia argentijolii Bellows & PelTing in the U.S. deselt southwest, its effectiveness in different cropping systems varies, Development and repro­ duction of a population of this parasitoid attacking B. argentifolii infesting cotton, Gossypium hirsutHH! L., and sweet potato, Iponwea. batatas L were quantified and compared, Females <24 h old contained an average of20 ova that averaged 0.072 mm in leng;th ane! 0.034 mm in width, Adult females lived an average of 5.9 d on cotton and 4.1 d on sweet potato and laid a lifetime average of 22.9 eggs on cotton and 23.1 eggs on sweet potato; there were no signific.mt differcnces of these parameters between host plant species. A preoviposition period of 0.61 d was recorded, ane! a maximum number of egg;s laid in a day was 69 on cotton and 13 on sweet potato. The average preimaginal developmental periods for males and females on either host plant were not significantly different and averaged 22.58 d. The mean number ofprogeny produced on cotton was 25.4 with 51,5% of these female, wherea~ the meaD number of progeny produced on sweet potato was 7,5 with 46,7% of these female. Life table parameters showed the net reproductive rate (Rol was 11.64, the generation time (Tel was 26,06 d, and the intrinsic rate of natural increase (I'm) was 0,0959 for parasitoids on cotton, with a preimaginal survival assumed at unity. On sweet potato Ro was 3,75, Te was 24.18 d, and I'm was 0.055 with preimaginal survival calculated at 0,3247. These profound differences relate to, among other things, differences in female foraging and oviposition behavior on host plants with different morphological features.