Influence of temperature and age of Nezara viridula L. eggs on the scelionid egg parasitoid, Trissolcus megallocephalus (Ashm.) (Hym., Scelionidae)

Abstract: Laboratory experiments were carried out to study the influence of temperature and age of Nezara viridula eggs on the rate of parasitism by Trissolcus megallocephalus, the rate of emerged parasitoids, the duration of developmental stages, the adult longevity and the daily rate of oviposition. The results indicated that the highest rate of parasitism 55.4 ± 2.37/female (92.33%) and the highest number of emerged parasitoids 55.10 ± 2.60 individuals/female (91.83%) were obtained when the females were reared at a constant temperature of 25°C. At 30°C, egg‐larval stage, pupal stage and total developmental stages showed the shortest developmental time. Results showed also a negative response between adult parasitoids longevity and temperature. Females deposited the highest number of eggs during the first day at the highest temperature of 30°C, while the females which were reared at 25°C, 20°C and 21–36°C fluctuating temperature deposited the highest number of eggs during the second day. The results also indicated that the parasitoid females attacked host eggs at all developmental stages before hatching. The rate of parasitism and the number of emerged parasitoids were relatively high except for host eggs more than 3 days old. The shortest duration of developmental stages (14.2 ± 2.86 days) were obtained at host eggs of two days old, and increased to (17.8 ± 2.39 days) at 5 days old with a significant difference (P < 0.05). No significant differences were obtained between the adult longevity and the different ages of host eggs.