Effect of different tomato cultivars on the biological characteristics of the wasp, Trichogramma brassicae an egg parasitoid of the tomato fruit worm, Helicoverpa armigera

Biological control of the tomato fruit worm, Helicoverpa armigera (Hübner) by means of inundative release of the egg parasitoid, Trichogramma brassicae (Bezdenko) is a part of an IPM program on tomato crops in Iran. This research was conducted to evaluate the effects of ten commercial tomato cultivars including Aras, Atrak, Korall, Mobil, Rio Grande, Sivand, Super Chief, Super Mobil, Super Queen and Super Urbana on biological characteristics of T. brassicae was studied at 26±1°C, 60±10% RH and a photoperiod of 16:8 L:D hours. The mean longevity of female parasitoid wasps ranged from 7.10±0.56 days on the Super Mobil to 8.05±0.49 days on Rio Grande without significant differences. Developmental period from egg to adult of T. brassicae on Super Urbana was highest (8.61±0.03 days) and lowest on the Aras (8.04 ± 0.02 days). The rate of parasitism was lower on the Super Urbana with 30.08 ±1.40% and highest on the Atrak with 35.86±1.56%. The average number of parasitized eggs by T. brassicae was higher (67.85±4.59 eggs/female) on the Rio Grande and lower on the Super Mobil (59.35±5.72 eggs/female). Female-biased sex ratio varied from 59.54±0.54% on the Aras to 62.65±0.40% on Rio Grande. The number of parasitoid progeny per host egg was highest on Super Chief (1.45 individuals per parasitized egg) and was lowest on Aras (1.37 individuals per parasitized egg).The percent emergence was not influenced by tomato cultivars and was about 90% for the entire treatments. The results suggest that differences between tomato cultivars are the causes of variation in the results of T. brassicae parasitism.