Parasitic hymenoptera play a vital role in rice ecosystems as biocontrol agents of pests. Surveys were conducted from August 2015 to January 2016 in three rice growing zones in Tamil Nadu: western zone, Cauvery Delta zone, and high rainfall zone. A total of 3,151 parasitic hymenoptera were collected, of which 1,349 were collected from high rainfall zone, 1,082 from western zone, and 720 from Cauvery Delta zone. Platygastridae, Ichneumonidae, and Braconidae were the most abundant families in all the three zones. The species diversity, richness, evenness as well as beta diversity were computed for all three zones via Simpson’s, Shannon-Wiener and Margalef indices. The results showed the high rainfall zone to be the most diverse and the Cauvery Delta zone the least diverse, but with more evenness. Pairwise comparison of zones using Jaccard’s index showed 75–79% species similarity.
For insect diversity studies to be of value, the sampling methods employed must produce samples representative of the community or taxon selected for the investigation. However, as yet, few evaluations on the variability and effectiveness of sampling methods have been undertaken. The survey was carried out in the rice fields during 2015-16 in Paddy Breeding Station, Tamil Nadu Agricultural University, Coimbatore. From this study a total of 1,019 parasitoid individuals were collected. Among six different collection methods employed for sampling hymenopteran parasitoids in rice ecosystem, the yellow pan trap at ground level was found to be the most effective method in trapping the parasitoids (27.2 ± 2.56 parasitoids per day) followed by sweep net method (12.1 ± 1.03 parasitoids per day). The next best sampling method is yellow pan trap erected at canopy level which recorded a mean of 9.2 ± 2.26 parasitoids per day. The other three traps viz., malaise trap, suction trap and light trap were found to collect less number (<1.5) of parasitoids per day.
The egg masses of yellow stem borer, larvae of leaf folder and rice horned caterpillar and eggs of ear head bug were collected randomly at fortnightly interval from four different varieties viz., CO 43, CO 50, CO 51 and CR 1009 from the rice field. The data was pooled and per cent parasitization was calculated to find out the varietal preference and seasonal variations of parasitoids. Among the four different varieties tested for the preference of parasitoids, per cent parasitization of stem borer egg mass was found to be more (26.59) in CO 50. The per cent parasitization of leaf folder larvae and rice horned caterpillar was found to be maximum in CO 51(40.29) and CO 43(33.21), respectively. In case of ear head bugs, the egg parasitization was maximum (27.70) in CO 50. The mean egg mass parasitization of stem borer was highest (71.88) in first fortnight of December. The larval parasitization of leaf folder and rice horned caterpillar were found to be maximum during the second fortnight of December (64.3) and the first fortnight of January (71.88), respectively. The parasitism rate of ear head bug eggs was maximum (62.95) during the second fortnight of December. Interestingly, phoresy exhibited by Sceliocerdo sp. an egg parasitoid of Neorthacris sp. was also recorded.
Surveys were conducted to explore the mymarid fauna from three different rice growing zones viz., western zone, Cauvery delta zone and high rainfall zone in Tamil Nadu during 2015-16. In the present study, 92 mymarid parasitoids comprising of 8 species under 7 genera viz., Anagrus sp., Anaphes sp., Camptoptera sp., Dicopus longipes (Subba Rao), Lymaenon delhiensis Narayanan and Subba Rao, Lymaenon munnarus Mani and Saraswat, Mymar pulchellum Curtis and Ptilomymar dictyon Hayat and Anis were collected. Alpha and beta diversity were computed for the three zones and the diversity indices (Simpson’s index, Shannon-Wiener index, Pielou’s index) revealed high rainfall zone as the most diverse zone, while Cauvery delta zone being the least diverse. Dicopus longipes is found to the predominant species in rice ecosystem. Jaccard’s index of species similarity comparison revealed 42.5 per cent similarity between western and Cauvery delta zones and 62.5 per cent similarity between high rainfall and Cauvery delta zones and 62.5 per cent similarity between high rainfall and western zones. Correspondence analysis and Bray-curtis cluster analysis were also done to understand the diversity assemblage of the mymarids that were collected.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.