Prabhakaran P., Radhakrishnan B., Srikumar K.K., Suresh Kumar B. (2017): Efficacy of certain common ferns against red spider mite Oligonychus coffeae and tea mosquito bug Helopeltis theivora infesting tea. Plant Protect Sci., 53: 232-242.In search for botanicals as an alternative remedy to synthetic chemicals in the pest control of tea plantations, ferns such as adiantum raddianum, asplenium aethiopicum, Cyclosorus interruptus, dicranopteris linearis, diplazium polypodioides, and Pteridium aquilinum were evaluated against the two major pests of tea, red spider mite Oligonychus coffeae Nietner and tea mosquito bug Helopeltis theivora Waterhouse, which are the foremost seasonal pests in tea fields, causing severe crop loss. Apart from synthetic chemicals, only the neem kernel extract is recommended in tea fields. The aqueous extracts of ferns were screened at different concentrations against these pests under laboratory and field conditions. The extracts of P. aquilinum and d. linearis showed good contact toxicity at a 5% concentration to O. coffeae. The acaricidal activity was observed in the order P. aquilinum > d. linearis > C. interruptus > a. raddianum > d. polypodioides > a. aethiopicum. Under field conditions, the extract of d. linearis and P. aquilinum showed a 50% reduction in the population of red spider mite and caused no phytotoxic effect to tea leaves. But their insecticidal activity was less pronounced against H. theivora. They exhibit antifeedant activity, which was sustained only for 24 hours. The photochemical screening of extracts showed a qualitatively increased level of saponins in P. aquilinum, d. linearis, and C. interruptus. The study shows that the aqueous extracts of d. linearis and P. aquilinum can be incorporated in the mite control programme in tea.Keywords: botanicals; aqueous extracts; acaricidal activity; insecticidal activity Tea occupies a major position among various plantation crops. It is grown in 50 different countries and the prime producers are India,

ABSTRACT:The anthocorid predator, Blaptostethus pallescens Poppius was studied for the first time on red spider mite (RSM), Oligonychus coffeae Nieter. Laboratory studies indicated that B. pallescens can be successfully reared on RSM. Incubation period was 4.4 ± 0.34 days. The total developmental period of five nymphal instars to adults was 17.1 ± 0.34 days. Blaptostethus pallescens nymphs consumed RSM in the range of 3.83 ± 0.18 to 17.37±0.95/day. Female B. Pallescens consumed more mites than male. The study clearly showed B. pallescens is a promising candidate in tea plantations for the control of red spider mite.

Helopeltis theivora is considered as one of the major pest in tea plantations causing considerable economic damage. Recent control strategies against this notorious polyphagous pest mainly depend on the application of insecticides. The study is focused on the antennal response of H. theivora on exposure to different insecticides using electroantenogram (EAG). The result showed that the insects perceive quinalphos as they are frequently exposed to it. The hierarchy of the EAG response of exposed and unexposed insects was quinalphos > bifenthrin > deltamethrin > thiamethoxam.

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The larva of green lacewing, Mallada desjardinsi (Navas) is an important predator of red spider mite (RSM) Oligonychus coffeae, infesting tea. Mallada desjardinsi is reported as potential biological control agent of O. coffeae, but the report on its parasitoids is scarce. Here we report the parasitism of M. desjardinsi by a species of ichneumon wasp. Mallada desjardinsi is the first host report for Dichrogaster fulvescens seminigra Townes, a sub species of Dichrogaster fulvescens. Five field collected larvae of M. desjardinsi were being found to be parasitized by this parasitoid. Dichrogaster fulvescens emerged after 9.5 days of pupal period.