The main requirement for insect conservation is biodiversity documentation. In order to meet this need, three ecotypes of reduviid predators were surveyed in Tamil Nadu, India's southern Western Ghats. 641 individuals from 29 species and 7 subfamilies in total were counted. Reduviinae and Harpactorinae had the most species among the seven subfamilies. These results are consistent with research carried out in Tamil Nadu and other Indian states (Louis, 1973) by Ambrose (1980), Vennison (1989), Sahayaraj (1991), Edwin (1997), and Sivaramakrishnan (2009). As seen in our study, landscapes generally have an impact on the population and community ecology of species, including insects (Hunter, 2002).Murugan (1988) and Ravichandran (1988) recorded 317 reduviid species from Indian faunal limits. Later, Ragupathy et al., (2001) and Ragupathy and Sahayaraj (2002) recorded 114 reduviids which were found to dwell exclusively in TF (36%) and SAZ (10%), shared in three habitats (7.6%) and adjacent agro-ecosystems (4%). But the present results clearly indicate that reduviid predators are more predominantly present in scrub jungles (70%) than in SAZ (20%) and TF (10%), which coincide with high Shannon Weiner Index (2.552), Berger Parker index (d = 0.995) and Menhinick’s index (Dmn = 1.490) observed for the former category. Hence we presume that these three indices could be considered for calculating Reduviid diversity. Simson’s and Mangalef’s indices were more in favor of semi-arid zone than tropical rain forest and scrub jungle. Reduviids are evenly distributed (E = 0.969) in tropical rain forest than in semi-arid zone (E = 0.686) and scrub jungle (E = 0.408) of Southern Western Ghats of Tamil Nadu. The similarity index in Aralvoimozhi site 1 has the highest value in similarity index (0.67), followed by site 2 (0.4) and remaining 4 sites were dissimilar when compared to the former sites. In Killikulam site 1 and 3 have the highest value of 0.256 and 0.25 respectively. The lowest value was 0.0328. In Godayar, this index shows the highest in site 2 (0.333) and lowest in site 3 and 6 (0). The species richness and abundance of predator is recorded as the highest in Aralvoimozhi. This area is located in the gap of Western Ghats, where moderate climatic factors are prevalent. Goel (1978) from his lunar periodicity population count mechanism reported a high collection of hemipterans when there is moderate temperature, higher humidity and lower rainfall. There is a high possibility that the thriving reduviid abundance in Aralvoimozhi is monitored and made possible by the moderate climatic conditions.
Plant density coupled with other biotic and abiotic factors could also have a major influence on the diversity of species and numbers of insects. (Shah et al., 2003). Maximum collection of reduviids was in the month of July which had a low rain fall and high humidity. Ambrose (1980) and Vennison and Ambrose (1990) reported that the reduviid population was solely regulated by prey population. But the abiotic factors viz., rainfall optimum humidity and moderate temperature or minimum temperature appeared to be essential for maintaining a good prey population as well as predatory reduviid population. Vennison and Ambrose (1991) pointed out that the predatory reduviid population was dependent on the prey population as well as the climatic factors. But later, it was reported by Sahayaraj and Ambrose (1993) and Thanasingh and Ambrose, (2006) that reduviid population was directly influenced by a number of abiotic factors in scrub jungle as well as semi-arid zone. Humidity and temperature seems to have very little influence on reduviid population dynamics. Since we have not recorded the abiotic factors, we are not in a position to support the results of the previous investigations. One of the reasons for this is availability of verities of microhabitat in the forest ecosystem which can protect the reduviid species from the direct influence of these major physical parameters (Edwin and Ambrose, 1996). Predacious insects are habitat specialist but feeding generalists (Boone, 2008) as indicated in our study.
Ambrose (2006) published the check list of Indian reduviids, where he reported 13 reduviid from Aralvoimzhi (N. therasii, Alcmena spinifex, M. nodipes, Rhaphidosoma atkinsoni, R. fuscipes, R. kumarii, R. longifrons, R. marginatus, Scipinia horrida, C. Brevipennis, E. tibialis A. pedestris and Paralisarda malabarica), 5 from Killikulam (A. quinquespinosa, E. tibialis, C. Brevipennis, R. fuscipes and H. nigroviolaceous) and nine predators from Godayar (Ectrychotes annamensis, Labidocoris tuberculatus, Endochus umbrinus, E. plagiatus,L. guerini, Neovillanovanus macrotrichiatus R. kumarii, Sphedanolestes himalayensis, S. pubinotum). Acanthaspis predestris, E. slateri, I. armipes, N. therasi, Oncocephalus annulipes, Oncocephalus notatus, Pygolampis unicolor, R. marginatus and Sastrapada elongata are new report to Killikulam semi-arid zone of SWG. A. pedestris, Acanthuspis carinata., C. brevipennis, Coranus atricapillus, E. cordiger, E. plagiatus, E. slateri, E. tibialis, Endochus sp., H. melanospilus, Lisarda sp., M. picipes, Oncocephalus annulipes, Oncocephalus sp, Peirates affinis., Physorhincus sp. were reported for the first time in Aralvoimozhi. Similarly, from Godayar, we recorded C. crocatus, C. gilves, Endochus sp., Epitus bicolor, Irantha armipes, Rhaphidosoma atkinsoni and Sycandus rectiatus for the first time.
From all this observation, it has been noted that the diversity of reduviid in Aralvaimozhi is comparatively high. This is the first report to highlight the high-level biodiversity of predatory hemipteran in Aralvoimzhi in Southern Western Ghats. The abiotic factors like topology highly influenced the species diversity. The species specificity in the area was identified. The A. pedestris and E. slateri were present only in moderately dry areas, that means semi-arid zones and scrub jungles, these insects do not have fully flying adapted. The tropical rain forest is the boarding of some fully flying.
Predators such as Sycanus rectiatus, Cynacoris crocatus. Sahayaraj (2006) reported that the reduviid population has been observed abundantly in dry regions, even at lower rain fall and humidity and moderate temperature. The Aralvoimozhi SAZ has been shown to have the highest population diversity, which validates the findings of the current study and the earlier publications. Additionally, our thorough examination of the reduviid fauna in the Southern Western Ghats indicates that the region is home to the most diversified reduviid fauna currently described. Our research presents a framework for ongoing research in the Western Ghats, a region with important conservation ramifications, and offers a paradigm for future surveys and comparative evaluations of Western Ghats reduviid diversity and abundance.