Study On The Emulsifiable Formulation Metarhizium Flavoviride Mf82and Its Application Of Technology

The brown planthopper (BPH) Nilaparvata lugens St l is an important rice insect pestthat can cause serious damage to the rice production in China and Southeast Asia. In orderto search for biological control methods to manage Nilaparvata lugens (St l), in this paper,several entomopathogenic fungi strains were tested in this experiment and one strain ofMetarhizium flavoviride Mf82with higher virulence to BPH was selected. On the basis ofbioassay, focusing on its development of the emulsifiable formulation, including thescreening of the emulsifiers and other additives compatible with the strain better chemicalpesticides screening and mixed, in order to provide technical support for the biologicalcontrol system of the brown planthopper. The primary results are as follows:1、Screening for high virulence strain of entomopathogenic fungi against Nilaparvatalugens St l10strains of entomopathogenic fungi were chosen to the bioassay and the virulence toBPH were determined. The results showed that the pathogenesis effects of fungi to BPHwere significant difference between10strains. One of the M. flavoviride strain Mf82hasthe highest virulence to BPH, when BPH were infected after10days, the cumulativemortality was81.7%, respectively, significantly higher than other treatments. Regressionequation and half lethal time (LT50) of each treatment were calculated from the bioassaydata. LT50of Mf82strain was4.6days, faster than other treatments (6.9~14.0days).Combination of BPH mortality and LT50data, Mf82strain can be considered the highestvirulence of BPH in all the tested fungi.2、The development of the emulsifiable formulationUse the spore germination rate of Mf82as indicators, measured compatible of thedifferent carrier oils with Mf82conidia at room temperature. The results showed that thebest compatibility of salad oil and spores,7days and14days, the germination rate were78.50%,72.50%.0.1%SDS is considered to be the appropriate amount of emulsifier.0.1%SDS in thecarrier oil, storage of7days and14days after spore germination rates were88.26%,80.83%; In stability, the suspension was emulsified oil droplets smaller, short-term standfor no stratification.Use the index of protective efficacy as indicators, screenned0.2%ascorbic acid as UV protection agent of the emulsifiable formulation.3、The virulence of emulsifiable formulation Mf82against the N. lugensOn the basis that a kind of emulsifiable formulation of Mf82was studied in thelaboratory, the bioassay of virulence of emulsifiable formulation Mf82against the N.lugens was carried out. The results showed that the daily cumulative mortality of N. lugensincreased with the infect concentration of conidial suspension, the highest concentration(1048conidia/mm~2) treatment caused85.0%. A time dose mortality model was used toanalyze the bioassay data and the model fitted the data well, resulting in parameters forestimating the time and dose effects. The estimated LC50values on day7and9aftertreatment were2.1×103,9.9×102conidia/mm~2, respectively；while LC90were7.8×104，3.7×104conidia/mm~2, respectively. The median lethal time of the emulsifiable formulationof M. flavoviride to the N. lugens differed at various logarithmic dose, values of LT50oftested agents were shortened with logarithmic dose, logarithmic dose increased from7.0to8.0, the LT50values reduced from8.9days to5.7days. The results showed that theemulsifiable formulation of M. flavoviride to N. lugens with high virulence, and this newemulsifiable formulation has the potential to practice in biocontrol of N. lugens．4、Study on the compatibility of M. flavoviride Mf82with chemical pesticidesUse suppressing rate of mycelia growth of Mf82as indicators, the compatibility oflethal concentration, sub-lethal concentration and sub-sub-lethal concentration ofpesticides with Mf82isolate were evaluated. The results showed that: the fungicidecarbendazim spores strong inhibition of the lethal concentration and sub-lethalconcentration, the inhibition rates were81.68%and77.38%; the imidacloprid,deltamethrin and buprofezin were compatible with Mf82. Inhibition of the weakest wasimidacloprid, the inhibition rate in the sub-sub-lethal concentration of9.16%, compatiblewith the spores of the best; the sub-sub-lethal concentration of deltamethrin and buprofezininhibition rate of only9.71%and13.58%, and spores compatibility was also very good.5、The virulence of the emulsifiable formulation Mf82with chemical pesticide againstthe N. lugensThis study investigated the virulence of emulsifiable formulation Mf82against the N.lugens with low amount of chemical pesticides mixed. The results showed that: separatethe emulsifiable formulation Mf82on10day cumulative mortality rate was83.86%; buprofezin, deltamethrin and the imidacloprid mixed with the emulsifiable formulationMf82, the cumulative mortality on10day, respectively,88.43%,91.70%,95%. And alsoshorted the incubation period, the cumulative mortality in the first2day began to risesignificantly. Three the LT50mixture was less than the emulsifiable formulation Mf82, inparticular imidacloprid mixture LT50was only3.82days. Imidacloprid was better synergistfor the emulsifiable formulation Mf82.