Screening And Evaluation Of Botanical Pesticides And Plant Extracts For The Control Of Ditylenchus Destructor

Ditylenchus destructor is an internationally recognized quarantine nematode,which seriously harms the production and storage of potato.Using plant-derived active substances to control nematodes is a safe and non-target biological safety control measures,which can provide a new basis for biological control of nematodes.In this study,we explored the action mode,control effect and toxicity test of plant-derived pesticides on D.destructor.The main results were as follows:1.In this study,the direct contact toxicity method was used to determine the indoor toxicity of six plant-derived pesticides to D.destructor,observe their morphological changes,and determine their effects on the humoral permeability of nematodes.The results of indoor toxicity determination showed that after 24 h,5%carvacrol AS had the strongest toxicity to D.destructor,and the LC50 was 39.524 mg/L.The nematodes were stiff,and the vacuoles or cavities were found in the dead nematodes.After treatment with carvacrol AS,the dead nematodes were stiff,and no vacuoles or cavities were found in the dead nematodes.In addition,the six botanical pesticides increased the humoral leakage of D.destructor under LC50 conditions,and the electrical conductivity of nematode suspension treated with botanical pesticides was significantly higher than that of water control.At 24 h,the electrical conductivity of nematode suspension treated with 5%carvacrol AS was the highest,which was 70.40 us/cm.2.The chemotaxis of D.destructor on pesticides of different plant sources showed that5%parsley AS,1.3%matrine AS,and 0.3%neem EC showed neutral effects on D.destructor,and 1%cnidium EW and 5%eucalyptus EC showed a neutral effect on D.destructor CF indices of 2.31 and 2.49,respectively.0.5%quinoaline SL showed a repellent effect on D.destructor with a Cf index of 0.48.3.In this study,the effects of several botanical pesticides on potato decaying D.destructor acetylcholinesterase were determined,and the results showed that botanical pesticides had greater acetylcholinesterase activity in D.destructor,and manifested as activation at 12 h,and the acetylcholinesterase activity in the subsequent treatment of nematodes was continuously reduced.Treated for 48 h,0.5%versoline,1.3%matrine and5%carvacrol have a strong inhibitory effect on acetylcholinesterase activity,which will cause disturbances in nematode behavior and nervous system,and affect the normal movement of nematodes.4.The results of the test on the control effect of botanica pesticides on D.destructor showed that there was a significant difference between the 5%carvacrol AS root irrigation treatment and the control treatment,and the indoor and field control effects reached 65.73%and 53.55%,respectively.5%carvacrol AS has high virulence and good control effect,and can be used as a recommended agent for the prevention and control of D.destructor.5.Studies on the toxicic activity of plant extracts on D.destructor showed that 12 pairs of D.destructor in broccoli showed strong hacidic activity:after treating D.destructor with10 mg/L alcohol,acetone,ethyl acetate and petroleum ether extract for 72 h,the corrected mortality rates of nematodes reached 79.31%,84.09%,86.65%and 35.65%,respectively.Then the use of the hydrolyzed product of glucoside in broccoli isothiocyanate to the killing activity of D.destructor for re-screening,wherein methyl isothiocyanate after 24 h,48 h and72 h,LC₅₀ were 1.906 mg/L,0.006 mg/L and 0.005 mg/L,respectively,superior to methyl isothiocyanate and propyl isothiocyanate,it is necessary to continue to study the mechanism of action of methyl isothiocyanate on D.destructor in follow-up experiments.