P V Rami Reddy

Effect of soft electron treatment on adzuki bean weevil, Callosobruchus chinensis (L.) (Col., Bruchidae)

Abstract:  Laboratory experiments were conducted to study the effect of soft electron (low‐energy electron) treatment on adzuki bean weevil, Callosobruchus chinensis (L.), a major pest of stored legume seeds. Adzuki bean (Vigna angularis) seeds containing weevils of different ages (0, 2, 4, 6, 8, 10, 12, 14, 16 and 18 days), were exposed to electrons at an acceleration voltage of 170 kV for 20 min (10 kGy). The radiation sensitivity of the insect decreased with increasing age. The egg stage was highly susceptible to electron radiation whereas the 18‐day‐old stage (fully developed adults ready for emergence) was the most tolerant, and treatment at a higher energy (200 kV equal to 10 kGy) was necessary to achieve an 80% mortality of this stage. However, the longevity, fecundity and fertility of the surviving adult insects were adversely affected by the electron treatment and they failed to complete their life cycle. The sex ratio of weevils was not significantly affected by the electron treatment, suggesting an equal vulnerability of both sexes. Electron treatment did not affect the germination capacity of adzuki bean seeds, so soft electron irradiation represents a safer method for the disinfestation of adzuki beans.

The Shoot and Fruit Borer, Conogethes punctiferalis (Guenee): An Important Pest of Tropical and Subtropical Fruit Crops

Conogethes punctiferalis is a polyphagous species, well distributed in the tropics and subtropics. In Punjab and Himachal Pradesh, India, Conogethes has become a serious pest of plum, peach, pear, litchi and pomegranate. On guava, Conogethes is a major pest from the beginning of the twenty-first century infesting up to 20% fruits in Jammu and Kashmir, and Allahabad Safeda is the most susceptible cultivar to infestation. One of the ideal measures of protection would be to prevent moths from ovipositing on fruits for which the work on pheromones should be stepped up. While the components of pheromones have been identified, their proportion, wax supplement from the female hair pencils and trap designs need to be refined. Mass production and release of natural enemies on community basis and cultivation of tolerant/resistant cultivars will go a long way in protecting fruit crops from borer damage.