Multiple decrement life table of spurge leaf defoliator moth, Simyra dentinosa (Lepidoptera: Noctuidae), in natural conditions of Urmia

To detect the main mortality factors acting on the immature stages of Simyra dentinosa Freyer, a biocontrol agent of weedy spurges Euphorbia spp. in West Azerbaijan Province, multiple decrement life table was constructed. All field experiments were performed at Urmia in 2001-2004. The mortality factors in the population of S. dentinosa under semi-field conditions were assessed over its three generations. The analyses of the data obtained indicated that larval parasitoids and miscellaneous factors in pupal stage had the highest role in population reduction of the moth. The highest mortality was found in the larval stage and caused by parasitoids. The most common larval parasitoids observed were Cotesia spp. (Hym.: Braconidae), Hyposoter didymator (Thunberg) (Hym.: Ichneumonidae), Exorista larvarum (L.) (Dip.: Tachinidae) and also Pales pavida (Meigen) (Dip.: Tachinidae). Moreover, the dominant species of larval stage were Cotesia plutellae (Kurdjumon), H. didymator and C. plutellae during 2001-2002, 2002-2003 and 2003-2004, respectively. They parasitized 8.11, 6.59 and 14.85% of larvae during the mentioned years, correspondingly. Furthermore, the pupal stage had also significant mortality that was caused by a complex of miscellaneous mortality factors. The results showed that these factors annihilate 12.07, 16.21 and 10.33% of pupae during above mentioned years, respectively. The results also indicated that the survival curve of S. dentinosa were type II during its three generation. Furthermore, the net reproductive rate of this moth during three years of studies was 105.04, 82.16 and 95.68, respectively.