Annals of Plant Protection Sciences
Year : 2002, Volume : 10, Issue : 1
First page : ( 31) Last page : ( 37)
Print ISSN : 0971-3573.

Interactive Effect of Sublethal Concentrations of Fenvalerate and Various Microbial Insecticides to Larval Instars of Spilarctia obliqua (Walker)

Kandru Sudhakar*, Dhingra Swaran

Division of Entomology, I.A.R.I., New Delhi 110 012, India.

*E-mail: <skandra@dow.com>

Abstract

The interactive effect of sublethal concentrations of fenvalerate in combination with dipel and biobit applied simultaneously or sequentially to different instars of Spilarctia obliqua was evaluated. Mixtures of high concentration of fenvalerate with highest concentration of Bt resulted in significantly higher mortality than the sum of the individual components to younger instars. With decrease in the concentration of fenvalerate, there was a reduction in mortality, lower than the sum of the mortalities of individual components. In the sequential application, delay in the application of fenvalerate up to 5 days after treatment with dipel or biobit, resulted in potentiation. However, the degree of synergistic effects differed between instars and concentration of the components. In the sequence of application of fenvalerate followed by Bt, potentiation resulted from the combinations at 5-day lag, involving higher concentration of both the components. Between the simultanaous components and sequential combinations, the later application method resulted in a significant increase III mortality, when applied at 5-day lag against all the instars and also at 3-day lag to 4-day old larvae.

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Key words

Dipel, Insecticides, Spilarctia obliqua.

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