Parasitic Behaviour of Xanthopimpla pedator Fabricius (Hymenoptera: Ichneumonidae) on Tropical Tasar Silkworm, Antheraea mylitta Drury (Lepidoptera: Saturniidae) Reared on Seven Forestry Host Plants in Uttarakhand, India

Abstract

Keywords:Forest silkworm, seasonal influence, host-parasitoid interaction, host-plant influence, sex-specific parasitization, biometric parameters of cocoon Antheraea mylitta Drury is a commercial silk producing forest insect in India and Xanthopimpla pedator Fabricius is its larval-pupal endoparasitoid, which causes pupal mortality that affects seed production. Effects of host plants, rearing season and their interactions on parasitic behaviour of X. pedator were studied here, as influence of these factors on biological success of X. pedator is not known. Seven forest tree species were tested as food plants for A. mylitta, and rate of pupal parasitization in both the rearing seasons were recorded and analysed. Results showed that rearing season and host plants significantly affected the rate of pupal parasitization in both the sexes. Pupal mortality was found significantly higher (14.52%) in second rearing season than the first (2.89%). Likewise, host plants and rearing seasons significantly affected length, diameter, and shell thickness of cocoons in both sexes. Out of all infested pupae, 85.59% were found male, which indicated that X. pedator chooses male spinning larva of A. mylitta for oviposition, but we could not answer satisfactorily the why and how aspect of this sex specific parasitic behaviour of X. pedator. Multiple regression analysis indicated that length and shell thickness of male cocoons are potential predictors for pupal parasitization rate of X. pedator. Based on highest cocoon productivity and lowest pupal mortality, Terminalia alata, T. tomentosa, and T. arjuna were found to be the most suitable host plants for forest based commercial rearing of A. mylitta in tropical forest areas of Uttarakhand state, where it has never been reared earlier. Sex and season specific interaction of X. pedator with its larval-pupal host, A. mylitta is a novel entomological study to find out explanations for some of the unresolved research questions on parasitic behaviour of X. predator that opens a new area for specialised study on male specific parasitization in Ichneumonidae. pedator is an idiobiont (such a parasitoid, which prevents further development of its host) solitary larval-pupal endoparasitoid (egg is laid in the host larva, but adult parasitoid does not emerge until host pupates) of A. mylitta. Xanthopimpla Saussure 1892 is one of the largest genera of Ichneumonidae and the species of the genus are endoparasitoids

Effect of rearing season, host plants and their interaction on economical traits of tropical tasar silkworm, Antheraea mylitta Drury- an overview

“…Major studies on A. mylitta includes: morphology of the larva , influence of temperature and photoperiod on termination of pupal diapauses (Jolly et al, 1970), effect of habitat and food (Prasad, 1980), effect of refrigeration on hatching (Dash et al, 1988;Nayak and Dash, 1989), growth and leaf yield of Asan and Arjun (Nayak et al,1988, and larval energetic in different food plants (Dash and Dash, 1989;Dash et al, 1996;Dash, 2001), occurrence of deformed cocoons (Dash and Nayak, 1990), rearing performance of A. mylitta with artificial diet (Akai et al, 1991), effect of food plants on cocoon crop performance (Dash et al, 1992(Dash et al, , 1994, preservation of seed cocoons ( Kapila et al, 1992), voltinism (Nayak et al, 1992), rearing and cocooning (Ojha et al, 1994), abnormal tasar cocoons (Mohanty and Behera, 1998), effect of starvation on larva (Dash et al, 1988), cocoon and post cocoon studies (Rao and Samitha, 2000), bioenergetics during diapauses (Satpathy, 2003), effect of outdoor cocoon preservation (Chakrabarty et al, 2003), reassuring livelihood functions of the forests to their dependents (Bhatia and Yousuf, 2013a), forest insect industry in collaborative forest management (Bhatia and Yousuf, 2013b), assessment on climatic suitability of Dehradun to introduce forest based rearing of A. mylitta in Uttarakhand (Bhatia and Yousuf 2013c) and parasitic behaviour of Xanthopimpla pedator on A. mylitta (Bhatia and Yousuf 2013d) The following highlights of the literatures, which are particularly relevant to the effect of rearing season, host plants and their interaction on biological and economical parameters of tropical tasar silkworm Antheraea mylitta, are given as under.…”

Mechanism of adult emergence in Xanthopimpla pedator (Fabricius)- a major pupal parasitoid of Tasar silkworm

“…Xanthopimpla predator is a noted parasitoid of Anthereae mylitta with a crop loss of 35-40 th %. X. pedator begins its life cycle in late 5 instar spinning larva of A. mylitta from the time of hammock formation to early cocooning stage and uses its long ovipositor to drill through silky envelope of spinning larva and deposits single egg in the abdominal segment th th preferably 5 to 7 day of cocoon spinning (Marepally, 2016;Aruna et al, 2014;Bhatia and Yousuf, 2013;Gadad et al, 2022).…”