The Effect of Temperature on the Parasitism of Three Species of Trichogramma Pintoi, T. brassicae, T. embryophagum (Hym.:Trichogra mmatidae) on Plutella Xylostella (Lep., Plutellidae) in Laboratory Conditions

Diamondback moth, Plutella xylostella (L), is one of the important pests of cabbage in the world. In the  present study, the effect of three temperatures of 20, 25 and 30ºС on quality and biological characteristics on the efficiency of Trichogramma brassicae, Trichogramma embryophagum, Trichogramma pintoi wasps was investigated. The mated females from each wasp species were put separately in the glass vial with 50 eggs of Plutella xylostella and the eggs were replaced daily for three days (totally, 150 eggs for each replication). Then the vials were put under controlled conditions (65±5RH, 16L: 8D) and in three temperatures. These tests were carried out in a Split plat design with 8 replications. Results showed that at the above temperatures, parasitism on 150 eggs was 44.62, 52.87 and 51.62 for T. brassicae; 52.12, 52.62 and 54.62 for T. embryophagum; 62.25, 68.50 and 65.75 for T. pintoi, respectively.The percentagesof adult emergence were 89%, 87% and 86% for T. brassicae; 90%, 91% and 90% for T. embryophagum; 89%, 89% and 88% for T. pintoi and Sex ratio of females were 0.63, 0.60 and 0.59 for T. brassicae; 0.67, 0.64 and 0.58 for T. embryophagum; 0.62, 0.59 and 0.38 for T. pintoi. Also, results showed that the percentage of adult emergence for three species did not have any significant difference. T. pintoi had the most parasitism,and the most Sex ratio belonged to T. embryophagum and the least sex ratio belonged to T. pintoi. Therefore, based on these results, the studied species can be useful in the release program of this parasitoid for the biological control of P.  xyllostella.