Taxonomic studies on indian belonnotus (coleoptera: curculionidae: ceutorhynchinae)

Abstract

The study entitled “Taxonomic studies on Indian Belonnotus (Coleoptera: Curculionidae: Ceutorhynchinae)” was undertaken in the Department of Entomology, College of Agriculture, Padannakkad during 2013-2015. The members of the tribe Mecysmoderini of the subfamily Ceutorhynchinae are one of the very large, diversely represented group of weevils in India, compared to other geographical regions of the world. Amongst the diverse genera representing of this tribe in India, genera Belonnotus and Mecysmoderes are important as it is distributed in Oriental region. A total of eighteen species are reported worldwide, out of which ten species are known from India in genus Belonnotus, whereas 26 species are known to be reported from worldwide in genus Mecysmoderes, of which five are known from India. Some of these species are major pests on economically important crops such as cucurbitaceous and cruciferous vegetables, as they cause pitting on the leaves and fruits. Some ceutorhynchine species feed on weeds and therefore are considered as biological control agents. The only substantial work on these weevil groups had come from Pajni and Kohli (1982). The available information is limited and lacking in essential diagnostics especially genitalia and morphometric observations. Hence, the present study was undertaken with objectives of survey and collection, study of morphological characters, redescription of species and formulation of taxonomic keys for the identification of the species. The present study was based on the collections from Malabar Insect Repository, College of Agriculture, Kerala Agricultural University, Padannakkad, Kerala and the specimens loaned from National Pusa Collection, Indian Agricultural Research Institute, New Delhi. Collections were also made through surveys from different parts of Kerala and Karnataka. The study constitutes five species belonging to two genera. All the species known so far under genera Belonnotus and Mecysmoderes have been taxonomically described. The descriptions of all the species studied are supplemented with taxonomic characters of genitalia and morphometric observations. An annotated checklist of the world Ceutorhynchinae had been prepared and these covered a total of 1316 species in worldwide distributed under 90 genera while the number of species reported from India is 45 distributed under 5 tribe and 13 genera. The geographic distribution of these species had been documented by taking up to date literature. The discrepancies in the description of the genera and species had been corrected and descriptions standardized to a uniform format loaded with morphometric ratios. Taxonomic keys to the species of all these two genera have been formulated and augmented with valid characters. Thus the present study fulfills to bridge a glaring lacuna of knowledge on these weevils and to keep its taxonomy on International standards.