Kannapiran Ethiraj

Blood sucking parasites not only cause economic loss but also transmit numerous diseases. Dermanyssus gallinae, an obligatory blood feeding ectoparasite causes huge production loss to the poultry industry. Mosquitoes act as vector for transmitting several viral and parasitic diseases in humans. Acaricide resistance limits the control of these parasites. The present study was aimed to control the parasites using chitinase that have selective degradation of chitin, an important component in exoskeleton development. Chitinase was induced in Streptomyces mutabilis IMA8 with chitin extracted from Charybdis smithii. The enzyme showed more than 50% activity at 30–50 °C and the optimum activity at 45 °C. The enzyme activity of chitinase was highest at pH 7.0. The kinetic parameters K_m and V_max values of chitinase were determined by non-linear regression using Michaelis–Menten equation and its derivative Hanes-Wolf plot. The larvicidal effect of different concentrations of chitinase was evaluated against all instar larvae (I–IV) and pupae of An. stephensi and Ae. aegypti after 24 h of exposure. The percentage of mortality was directly proportional to the chitinase concentration. Bioassay for miticidal activity showed that chitinase had excellent miticidal activity (LC₅₀ = 24.2 ppm) against D. gallinae. The present study suggested the usage of Streptomyces mutabilis for preparation of chitinase in mosquito and mite control.

Goatfishes are tropical marine fishes that belong to the family Mullidae. Goatfishes are recognized by their bright color with strips and the presence of two long unbranched barbells on the chin. In the last decade, the number of goatfish species has increased noticeably (20 new species) owing to the interest of researchers in coastal fish diversity. Five specimens of Upeneus margarethae were reported for the first time from the Bay of Bengal region. The species has expanded its distribution range to the Thondi and Chennai coast of the Bay of Bengal. Five Upeneus margarethae were collected using commercial trawlers from August 2019 to January 2020. This species is characterized by having VIII dorsal spines, 13-14 pectoral fin rays, Lateral line 28-29, Gill rakers 20-21; 4 bars on both upper and lower caudal-fin, which was partly visible, and orange lateral mid-body stripe passing from eye to base of the caudal-fin. The detailed morphometric and meristic characters with a fresh color pattern representing images for the first time from the Palk Strait, Southeast coast of India, agree with the holotype specimen and comparable records from other areas of the world.