Entomological Society of IranJournal of Entomological Society of Iran0259-999643220230622Temperature-dependent parasitism model of Trissolcus grandis Thompson (Hymenoptera: Scelionidae)Temperature-dependent parasitism model of <i> Trissolcus grandis </i>Thompson (Hymenoptera: Scelionidae)879612846510.61186/jesi.43.2.1FAMasoud Amir MaafiIranian Research Institute of Plant Protection, Tehran, Iran.0000-0002-8636-4299Journal Article20230129<strong>Abstract. </strong><em>Trissolcus grandis</em> Thompson<strong> </strong>(Hymenoptera: Scelionidae), a native Sunn pest egg parasitoid in Iran, has the potential as a biological control agent for sunn pest, <em>Eurygaster integriceps</em> Puton (Het.: Scutelleridae). However, its ecological characteristics have remained unclear. Thus, this study aimed to develop a parasitism model of <em>T. grandis</em> with sunn pest egg as host. In order to obtain the data for the model, the longevity, survivorship and parasitism capacity of the adult female <em>T. grandis </em>were examined at nine constant temperatures (15, 17.5, 20, 25, 27.5, 30, 32.5, 35, and 37.5±0.5 °C), relative humidity 65 ± 5 % RH, and a photoperiod of 16:8 (L:D) h. Longevity (mean±SE) decreased as temperature increased and was the longest at 15°C (73.18±3.86 days) and the shortest at 35°C (18.98±0.48 days). A modified model of Sharp-DeMichele well described adult developmental rate (1/mean longevity) in the range of studied temperatures (<em>r</em><sup>2</sup> = 0.994) and was used to calculate the physiological age. The mean total host eggs parasitized/female (mean±SE) was greatest at 17.5°C (275.84 ± 3.21 host eggs) and lowest at 15°C (25.06 ± 3.221 host eggs). The temperature-dependent total parasitism, the age-speciﬁc cumulative parasitism rate, and the age-speciﬁc survival rate were best described by an extreme value function (<em>r</em><sup>2</sup> = 0.934), the two-parameter Weibull function (<em>r</em><sup>2</sup> = 0.967), and a sigmoid function (<em>r</em><sup>2</sup> = 0.979), respectively. I anticipate that the ﬁtted models and parameters may be useful in developing a population model for <em>T. grandis</em> and lead to a better understanding of its parasitism strategy.<br /><strong> </strong><strong>Abstract. </strong><em>Trissolcus grandis</em> Thompson<strong> </strong>(Hymenoptera: Scelionidae), a native Sunn pest egg parasitoid in Iran, has the potential as a biological control agent for sunn pest, <em>Eurygaster integriceps</em> Puton (Het.: Scutelleridae). However, its ecological characteristics have remained unclear. Thus, this study aimed to develop a parasitism model of <em>T. grandis</em> with sunn pest egg as host. In order to obtain the data for the model, the longevity, survivorship and parasitism capacity of the adult female <em>T. grandis </em>were examined at nine constant temperatures (15, 17.5, 20, 25, 27.5, 30, 32.5, 35, and 37.5±0.5 °C), relative humidity 65 ± 5 % RH, and a photoperiod of 16:8 (L:D) h. Longevity (mean±SE) decreased as temperature increased and was the longest at 15°C (73.18±3.86 days) and the shortest at 35°C (18.98±0.48 days). A modified model of Sharp-DeMichele well described adult developmental rate (1/mean longevity) in the range of studied temperatures (<em>r</em><sup>2</sup> = 0.994) and was used to calculate the physiological age. The mean total host eggs parasitized/female (mean±SE) was greatest at 17.5°C (275.84 ± 3.21 host eggs) and lowest at 15°C (25.06 ± 3.221 host eggs). The temperature-dependent total parasitism, the age-speciﬁc cumulative parasitism rate, and the age-speciﬁc survival rate were best described by an extreme value function (<em>r</em><sup>2</sup> = 0.934), the two-parameter Weibull function (<em>r</em><sup>2</sup> = 0.967), and a sigmoid function (<em>r</em><sup>2</sup> = 0.979), respectively. I anticipate that the ﬁtted models and parameters may be useful in developing a population model for <em>T. grandis</em> and lead to a better understanding of its parasitism strategy.<br /><strong> </strong>https://jesi.areeo.ac.ir/article_128465_db75d02e99ce9ab3450f27fb2f1c5bee.pdf