Feeding Efficiency of Green Lacewing, Chrysoperla carnea (Stephens) against Different Species of Aphid in Laboratory Conditions

Green lacewing, Chrysoperla carnea Stephens (Neuroptera: Chrysopidae) is the most effective polyphagous predator of different species of aphids and is commonly known as “aphid lion” . The experiment on feeding efficiency of green lacewing was studied in the laboratory of Entomology Division, NARC, Khumaltar, Lalitpur, Nepal from 21st , December 2015 to 26th, March 2016. The known number of predatory larva of green lacewings were fed with known number of seven different species of live aphid and frozen Corcyra eggs representing each treatment. The treatments were replicated four times. The predatory efficiency was calculated by counting the number of consumed host per day. The result revealed that the predatory efficiency of C. carnea larvae were increased from first to third instar and third instar were more voracious as compare to first two instars. It consumed significantly the highest rice moth, Corcyra cephalonica followed by Aphis craccivora and others aphid species, respectively. From this experiment, it is evident that the green lacewing is potent bio-agent against different aphid species and hence further research is required simultaneously in the farmer’s field conditions.Int. J. Appl. Sci. Biotechnol. Vol 5(1): 37-41

Study on Web-Site Attributes and Predatory Efficiency of Dark Tetragnathid Spider in Point Calimere Wildlife and Bird Sanctuary

Spiders represent one of the most abundant components of the predatory arthropods in terrestrial ecosystem. Their effectiveness at restricting pest populations, both alone and as part of natural enemy complex has well demonstrated in many countries. The web, web-site attributes and predatory efficiency of Dark Tetragnathid Spider Tetragnatha mandibulata were assessed in Point Calimere Wildlife and Bird Sanctuary between August 2015 and March 2016. In the present study, the spiders used limited number of plants species. The relationship between web architecture and web-site attributes was estimated using Pearson’s correlation. Number of spiders recorded in the web showed the positive correlation with web horizontal and vertical length of the capture areas (p<0.05). Similarly, the web circumference showed the positive interaction with plant height and canopy width (p<0.05), which clearly indicated the importance of vegetations across the webs of Dark Tetragnathid Spider. Further, the microhabitat selection and utilization could also be impacted by non-trophic factors like structural features of plants that provide architectural supports to spiders. A total of 4620 insect pests comprising seven orders were entangled by the webs of dark tetragnathid spiders. Number of spiders in the web were positively correlated with number of insect pests (p<0.05), which clearly explained that the Dark Tetragnathid spiders restricting pest populations and therefore they are considered as useful organism in biological control.