Parasites-predators: Their occurrence and invasive impact on the tropical tasar silkworm Antheraea mylitta (Drury) in the zone of central India

Abstract

Tasar silk is produced by the wild silkworm Antheraea mylitta (Drury) (Lepidoptera: Saturniidae). Owing to its inherent wild nature, the silkworm is exposed to a complex of parasites, predators and diseases that reduce the total silk production. Occurrence and invasion by three parasites and nine predators of A. mylitta are studied here. Moreover, on the basis of their attack and symptoms of parasitism and/or predation, percentage of crop loss (mortality) of A. mylitta is calculated. The parasites including Xanthopimpla pedator (Fabricius) (Hymenoptera: Ichneumonidae) were observed as a major pupal endoparasitoid of A. mylitta, which affects about 7-12% of tasar cocoon. In addition, the beetle Dermestes ater (De Geer) (Coleoptera: Dermestidae) also affects the pupa/cocoon of A. mylitta, while the Tachnid fly, Blepharipa sp., recognized as a larval-pupal parasite of the silkworm, cause about 1-2% and 2-3% of tasar crop loss respectively. Consequently, among the predators, Canthecona furcellata (Wolff) (Pentatomidae: Hemiptera), was observed as a major predator of A. mylitta that causes about 6-11% of tasar larval mortality. However, 2-3% and 3-4% of crop mortality occurs due to predation by Hierodula bipapilla (Serville) (Mantidae: Dictyoptera) and Vespa orientalis (Linnaeus) (Vespidae: Hymenoptera) respectively. The predatory ants Oecophylla smaragdina (Fabricius) (Formicidae: Hymenoptera) and Myrmicaria brunnea (Saunders) (Formicidae: Hymenoptera) also contribute to crop reduction by 4-5% and 3-5% respectively. Similarly, non-insect predators such as birds, lizards, squirrels, rats, etc. also affect the silkworm, which further reduces tasar silk production. Therefore, a survey was undertaken in the tasar rearing fields of Vidarbha, Maharashtra, India and the occurrence of the parasites and predators was studied.