Bionomics and some behavioural aspects of the mango stone weevil, Sternochetus gravis (Fabricius) (Coleoptera: Curculionidae).
De K., Pande Y. D.
Author Affiliation: Dep. Life Sci., Calcutta Univ. Post-Graduate Cent., Agartala 799?004, India.
Entomon 13 : 17-24
Abstract : The biology of Sternochetus gravis [S. frigidus] was studied on mangoes at different temperatures in the laboratory during 1982-84, using insects collected from the field in Tripuri, India. Reproductively immature adults overwintered inside seeds or other protective places during May-February. Females outlived the males and the survival period varied from 82.2 to 135 days. Provision of food significantly increased the longevity of females only. The male:female ratio was approximately 1:1.4. Mating occurred 10-15 days after termination of hibernation and lasted for 19-22 minutes. Oviposition occurred from March to May on immature mango fruits. The mean egg length was 0.6 mm. Eggs hatched after 4-65 days and the larvae fed on cotyledons or pulp. There were 5 instars and pupation occurred in flesh and seeds and lasted for 7-10 days. The average generation time was 41.2, 41.6 and 48.3 days at 22, 24 and 27°C, respectively, and this species was univoltine. S. frigidus was also recorded on Mangifera sylvatica in the field. The pest was attacked by 3 predatory species of Formicidae, Oecophylla smaragdina, Camponotus sp. and Monomorium sp., the entomogenous fungus Aspergillus sp. and the ectoparasitic mite Rhizoglyphus sp. The latter attacked larvae, pupae and hibernating adults.