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.

Here, we disclose novel mosquito-repellent synthetic hydrindanes based on noreremophilanes and nardoaristolone B which show increased activity against adult females of Aedes aegypti. The noreremophilanes and nardoaristolone B with hydrindane skeleton are structurally related to nootkatone with decalin skeleton, a well-studied natural product extracted from a grape fruit. Out of our library of compounds synthesized based on the noreremophilanes and nardoaristolone B scaffolds, NDS-100598 (compound 20) exhibits higher repellent and knock-down effects at a very low concentration (0.25 mg/cm2), while a few analogues showed considerably enhanced activity compared to racemic nootkatone. This is the first report documenting insect-repellent and knock-down activity of the noreremophilanes class of compounds.

No abstract

Ants are a ubiquitous component of insect biodiversity and well known for its eusocial behavior. They are active foragers, scavengers, and predators that are prevalent in the vicinity of several plantations and crops. They (workers) prey on many insect species and feed on nectar exudates from plants as well as sticky secretions produced by Homopteran and Lepidopteran insects. As ferocious foragers with an aggressive attacking habit (e.g., Oecophylla smaragdina), they have often been used as biological control agents against various crop pests. However, some economically important insect species like the wild silkworm, Antheraea mylitta, are also affected by these foragers, namely, O. smaragdina, Myrmicaria brunnea, Monomorium destructor, Monomorium minutum, etc., which leads to the loss in crop outcome. In addition, some of them are known to destroy several plant species including domesticated fruit trees, particularly at the seedling stage. In this chapter, the foraging habit and the predation biology of these foragers are explored, in which the sequence of attack, their interactions, and invasion caused are discussed. It may also serve as a primary source of information on the foraging and its invasive impact, which may help to protect and/or take counteractive actions against the foragers which are harmful to commercial cultivations.

A new scientific survey elucidates the preferred attack of stink bug Canthecona furcellata (Wolff.) (Hemiptera: Pentatomidae) on the spinning stage of the tropical tasar silkworm, Antheraea mylitta (Drury) (Lepidoptera: Saturniidae). The silkworm A. mylitta produces an excellent quality of wild silk; however, due to predation by C. furcellata, tasar silk production is reduced. The bug C. furcellata is the most invasive larval predator of A. mylitta and predation is high during early instars as well as the molting stage of the larvae. However, for the first time it is reported that the spinning stage is also preferable for attack by the stink bug. Both the nymphs and adults of C. furcellata attack the spinning silkworm; moreover, stink bug attack is observed in groups under field conditions. It is postulated that feeding preference is due to the concealed, non‐movable and less defensive stage of the tasar larvae during spinning. The predation of C. furcellata includes its approach on target larva of the tasar silkworm during spinning, where it inserts the proboscis inside the larval skin through the moist silk network of newly forming or formed cocoon. Most of the spinning larvae die from the attack and the normal seed cocoon fails to form. The mechano‐ and chemoreceptors, present on the antenna and proboscis of C. furcellata, play an important role in prey locating and the feeding mechanism. The life cycle of C. furcellata is also discussed in the present study.