Insect pest complex of tea [Camellia sinensis (L.) O. Kuntze] and their natural enemies in Uttarakhnd
Loading...
Date
2009-01
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Extensive surveys carried out during 2005-2008 revealed the occurrence of 58 arthropods pests associated with tea crop. All the species appeared new to Uttarakhand. Significantly, the class Insecta has been found as the predominant group of arthropods (56 species) over Arachnida (2 species) both qualitatively and quantitatively. Considering the species spectrum, the order Hemiptera and Orthoptera has been reported as the most prevalent insect order (14 species of each), followed by Lepidoptera and Coleoptera (10 species of each), Thysanoptera (5 species), Isoptera (2 species) and Diptera (1 species). The subtropical zone is represented highest number of 56 species of arthropods in comparison to tropical zone where only 23 species associated with tea. The seasonal incidence and relative abundance of these arthropods in tropical and subtropical localities has also been discussed in the thesis. Out of 58 species of arthropods reported Toxoptera aurantii (Boyer.), Thrips hawiiensis (Morgan), T. flavus Schrank, Caloptilia theivora Walsm.and Xenocatantops humilis Serville have been identified as the predominant species and therefore considered as the pests of major importance. A total of 18 species of natural enemies of tea pests have been reported for the first time from this region. The subtropical zone represented a total of 14 species and 04 species of predators and parasitoids respectively. In contrast to tropical zone where only 7 predators were recorded. The distribution, relative abundance along with prey/ host relation of these natural enemies in different phytogeographical locations has been also incorporated. The population density and seasonal fluctuations in population of some major insect pests of tea viz., tea aphid, tea thrips, Grasshoppers, and leaf roller on 5 commonly growing germplasms of tea viz., T-78, BSS-449, AV-2, UPASI-9 and Kangra Jat have been studied at Kausani with respect to different plucking seasons. The congenial seasons for tea aphid, thrips and leaf roller has been observed during Easter and Summer plucking seasons whereas for grasshoppers it was during autumn plucking season. Seven categories of pests attacking tea plantation have been identified on the basis of their nature of damage viz., sap suckers, defoliators, leaf rollers, leaf folders, leaf miners, root feeders and borers. The highest number of 22 species have been reported as sap suckers followed by defoliators (17 species), root feeders (11 species), leaf folders (4 species), borers (2 species), leaf roller (1 species) and leaf miner (1 species). Field experiments have been carried out to screen the tea germplasm viz., T - 78, BSS - 449, AV - 2, UPASI - 9, BSS - 379, RR - 17/44, P – 383 and P - 312 against some major insect pests of tea (tea aphid, tea thrips, Grasshoppers, and leaf roller) for resistance. The germplasms viz., BSS-379, RR-17/44, P-383 and P-312 have been identified to be resistant for major pests of tea and therefore may be promoted for the betterment of the tea industry in Uttarakhand. The thesis also incorporates the results of bioefficacy of some local plant extracts against the tea aphid, T. aurantii and tobacco caterpillar, Spodoptera litura Fabr. Out of 10 plant extracts tested in laboratory the extracts of Giardinia heterophylla, Zanthoxylum atmatum and Agave americana have beeb found to exhibit promising effect against the tea aphid and tobacco caterpillar. Laboratory experiment on the feeding propensity of the larvae of the syrphid, Episyrphus balteatus de Geer and larvae and adults of Coccinella septempunctata L. on third instar nymphs of tea aphid have been conducted. It has been observed that the larvae of these predators destroyed more number of aphids as compared to the adult of C. septempunctata (average feeding propensity 46.40, 33.20 and 29.96 third instar nymphs/ 24 hours respectively). the thesis also incorporates the results of per cent parasitisation by hymenopteran larval parsitoids on tea leaf roller, C. theivora and tea tortix, Homona coffearia at subtropical location, Kausani. Feeding propensity of common grasshopper, X. humilis observed in laboratory revealed that the insect consumed on an average of 0.550 mg of tea foliage/ 24 hours.
Description
Thesis-PhD
Keywords
insect pests, tea, Camellia sinensis, natural enemies, Uttarakhnd