| Curcuminoids are the main component of the medicinal plant turmeric. Due to their multiple pharmacological activities such as anti-inflammatory, anti-oxidation and anti-tumor, the curcuminoids has been extensively investigated. In recent years, with the expansion of the study, the agricultural activities of curcuminoids have been increasingly attracting people’s attention. As have good acaricidal activity against Tetranychus cinnabarinus, and various modes of action, the curcuminoids exhibit a good application foreground for the development as a new acaricide. Curcuminoids contain three kinds of monomers, of which the bisdemethoxycurcumin has an optimum acaricidal activity. In this paper, the bisdemethoxycurcumin was employed as the main object of study, and its stability and synergism were investigated. On this basis, the optimum preparation of bisdemethoxycurcumin SC was studied through the screening of the additive system. Then the activity against Tetranychus cinnabarinus was comprehensively evaluated, which provide a scientific basis and technical reserves for the development and application of the bisdemethoxycurcumin.1The stability investigation of bisdemethoxycurcuminThe chemical stability of bisdemethoxycurcumin is not very well, which makes it difficult to control quality, and to some extent restricts the development and application. The present was undertaken to obtain knowledge of the influence of pH condition and tempreture on stability characteristic of bisdemethoxycurcumin. As the results indicate, at the same tempreture, the degradation of bisdemethoxycurcumin accelerates with the pH value increasing, and the tendency is more pronounced under the alkaline condition. The effect of temperature shows a similar trend that higher temperature will promote the degradative reaction. In order to ensure the stability and efficacy of bisdemethoxycurcumin, an acidic condition is recommended in the pesticide formulation, and the pH value is appropriate to the range of5.02-6.09. In addition, bisdemethoxycurcumin and its preparations should be stored at low temperature or at room temperature.2The screening of synergist to bisdemethoxycurcuminThe synergism of5different synergists including triphenyl phosphate to bisdemethoxycurcumin was studied. Silicone TD-6408was selected as the optimum synergist through assessing LC50and LT50of each synergist. The result of futher research shows, the synergism of silicone TD-6408increases as its ratio to bisdemethoxycurcumin increases. However, the growth trend is not obvious as ever when the ratio increases from1:3(silicone TD-6408: bisdemethoxycurcumin, w:w). Considering both synergistic effect and cost of production, this paper selects the ratio1:3as optimal synergistic ratio.3The preparation research of8%bisdemethoxycurcumin SCThrough additive system screening and processing research, the preparation and processing method of8%bisdemethoxycurcumin SC were determined, which are as follows: bisdemethoxycurcumin original drug (bisdemethoxycurcumin86.7%, demethoxycurcumin and curcumin13.3%)8%, Morwet D-1104%, Xanthan gum0.025%, Veegum2.5%, Organobentonite2.0%, Organic silicon TD-64082.67%, ethylene glycol2%, SILFOAM SEII0.5%, glacial acetic acid0.001%, added water up to100%. Wet grinding method is applied, and the milling time is100min at the speed of2500r/min.4The quality test of8%bisdemethoxycurcumin SCThe quality indexes of8%bisdemethoxycurcumin SC were examined. The result shows that each index matches the National Quality Standards of pesticide suspension concentrate. The specific control indexes are as follows:the content of original drug is7.86%, pH value is5.191, average particle size is1.539μm, suspension rate is90.81%, water separating rate is not more than5.0%, residue rate after pouring is not more than3.0%, residue rate after washing is not more0.5%, lasting blistering is20.5mL, and both heat storage stability and cold storage stability are qualified.5The acaricidal activity evaluation of8%bisdemethoxycurcumin SCThe activity against Tetranychus cinnabarinus of8%bisdemethoxycurcumin SC was comprehensively evaluated. The toxicity measurement results show that, the48h contact activity against female adult mites of8%bisdemethoxycurcumin SC increass by2.29times compared with the original drug. In potted efficacy trials and field efficacy trials, the8%bisdemethoxycurcumin SC in400-fold diluted concentration conditions play better control effect on Tetranychus cinnabarinus, in which the control effects after7d in greenhouse and field are75.48%and82.53%respectively, Although the effect of thepreparation is still significantly lower than those of24%Spirodiclofen SC in3000times and73%Propargite EC in3000times, but it still can control the mites at a relatively low incidence of level. |
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