Abstract
BackgroundIn recent years, Microtermes obesi (Holmgren) (Blattodea: Termitidae) has been recorded as a major pest of tea crop, causes significant losses in production. Managing termite pests in tea crops through an integrated approach has been suggested, and the use of microbial biocontrol agent is one of the economical methods. The present study evaluated the pathogenic efficacy of an entomopathogenic fungus Metarhizium anisopliae s.l. (= M. anisopliae) against M. obesi damaging tea plants under field conditions.ResultsMetarhizium anisopliae s.l. was formulated as 5% aqueous suspension (AS). Large-scale field trials with formulated entomopathogen revealed that 1000 and 1200 ml concentrations of M. anisopliae s.l. 5%AS (each concentration containing 2 × 107 conidia/ml) each in 400 l of water/ha significantly (P < 0.05) reduced the population of M. obesi in tea gardens at Dooars and Darjeeling regions, India. In the field study, M. anisopliae s.l. was more effective than the standard insecticide and was non-pathogenic on the beneficial insects present in the tea gardens. In addition, M. anisopliae s.l. 5%AS had no phytotoxic effect on the tea leaves, with acceptable organoleptic attributes.ConclusionMetarhizium anisopliae s.l. isolate can be commercialized as an alternative natural termiticide to reduce the load of synthetic insecticides in the tea crop.
Highlights
In recent years, Microtermes obesi (Holmgren) (Blattodea: Termitidae) has been recorded as a major pest of tea crop, causes significant losses in production
The percent reduction of termite population M. obesi was slightly inferior in plots treated with lower concentrations of M. anisopliae s.l. 5%aqueous suspension (AS) at 600 and 800 ml/ha, Thiamethoxam 25WG at 100 g/ha as compared to plots treated with combination of M. anisopliae s.l. 5%AS @1000 ml/ha and Thiamethoxam 25WG at 100 g/ha and high concentrations M. anisopliae s.l. 5%AS, i.e.1000 and 1200 ml/ha (F2,126 = 19.75, P < 0.001)
Some commercial bio-insecticides based on M. anisopliae s.l. are available in the market, they have some limitations, for instance, some of them are regionspecific and having a narrow range of pesticidal activity as well as their short shelf life problems necessitates the search for new strains
Summary
Microtermes obesi (Holmgren) (Blattodea: Termitidae) has been recorded as a major pest of tea crop, causes significant losses in production. The live wood-eating termite, Microtermes obesi (Holmgren) (Blattodea: Termitidae), is one of the major pests of tea crop in India, especially in West Bengal (Dooars, Terai and Darjeeling) and Assam (Biswa and Mukhopadhyay 2013), which hamper the tea production amounting to 30–50% of total production (Zhang et al 2017). The live wood eating termites cause about 20–25% crop damage in northeast Indian tea plantations (Debnath et al 2012). Deka et al Egypt J Biol Pest Control (2021) 31:132 et al 2012) This pest remains active throughout the year, and un-checked infestation would lead to 100% crop loss, if appropriate management practices are not adopted (Fig. 1A, B)
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