Development of Hexamermis vishwakarma Dhiman (Nematoda: Mermithidae), a parasitoid of Leptocoris augur (Fabr.)

Abstract

Leptocoris augur, a well-known pest of the "Kusum" plant Schleichera oleosa Lour, is endoparasited by Hexamermis vishwakarma Dhiman. Using a two-tray technique, this worm has been successfully raised in a lab to learn about its biology. The five stages of this parasitoid's life cycle are eggs, pre-parasitic juvenile, parasitic juvenile, post-parasitic juvenile, and adult. Within 20 to 72 hours of the male and female post-parasitic nematodes mounting into adults, copulation takes place, lasting approximately 30 minutes, according to the biology of H. vishwakarma. After 10 to 25 days, ovipositions start on average 14 days after copulation. They produce 40 to 60 eggs per day for approximately a week, following which a few days must pass. Approximately 1200 to 1600 (on average, 1400) eggs are deposited during the course of 40 to 50 days. Internal fertilization occurs in the oviduct, which is the upper portion of the uterus. The incubation period, which lasts from July to September during the wet season, averages 16.5 days but can range from 14 to 20 days. The process of "spontaneous" egg hatching takes roughly 13 minutes on average, with an average of 1.5 minutes. The pre-parasitic juvenile enters the surrounding water after hatching. Its length ranges from 0.25 to 0.80 mm (average of 0.70 mm); they can live for three to five days without the host or culture media. Within 15 to 4 hours, the pre-parasitic juvenile enters the host bug and begins consuming nutrients from the adipose tissue, muscles, and haemo-coelomic fluid. As it grows in size, it is referred to as a "parasitic juvenile."

The size of parasitic- Juvenile juvenile parasites range in length from 12.0 to 194.0 mm and breadth from 1.25 to 2.25 mm. With an average of 20.5 days, the duration from penetration to emergency is estimated to be between 18 and 22 days. Parasitic juveniles are now known as "post-parasitic juveniles" once they emerge. While female nematodes are 52.0 to 194.0 mm in length and 2.00 to 2.25 mm in width, males are smaller, measuring 12.0 to 49.0 mm in length and 1.25 to 1.40 mm in width. Finally, within 17 to 30 days (on average, 24 days), post-parasitic juveniles moult in two adults. Adults resemble post-parasitic nematodes, with the exception that their vulva, spicules, and other features are completely formed. Furthermore, depending on changes in temperature and relative humidity as well as the condition of post-parasitic nematodes, the lifespan of male adults of Hexamermis vishwakarma ranges from 30 to 40 days, while that of female adults varies from 40 to 50 days.