Contribution to the study of the bio-ecology of Casama innotata (Lepidoptera, Erebidae) in arid climate in Tunisia

Description

At the end of December 2009, a defoliation of Vachellia horrida trees caused by mature larvae of Casama innotata was observed in Jebel Brourmet in southeastern Tunisia. The goals of this work are to study the biology of this pest, to track its dynamics, and to study mortality factors of pupae. A total of 350 pupae of C. innotata were collected in June 2018. In the laboratory, daily monitoring was carried out to follow the emergence of parasitoids and to estimate pupae mortality. Larvae collected during spring of 2019 were maintained in the lab until adult emergence. After matting, neonate larvae were reared on V. horrida leaves. Results showed that female fecundity is estimated at 189 eggs/female. Hatchlings that feed on optimal diets usually go through 5 stages. Pupae mortality was very high (96%). Mortality during molting and parasitism were the highest with respectively 37% and 33% compared to dried pupae (19%) and mortality caused by pathogens (10%). In total, three species of Hymenoptera were identified: Pimpla rufipes (Miller), Brachymeria sp. and Hockeria sp.. Pimpla rufipes was the dominant parasitoid species (63%). Foliage quality and temperature fluctuations can have major effects on the pests’ life cycle. Choice tests should be conducted to investigate larval feeding preferences.