| Tyrophagus putrescentiae(Schrank)and Sancassania berlesei(Michael)are cosmopolitan species of non-pyroglyphid mite.They are not only harmful to all kinds of storage products,but also an important pest of fungi production and economic insect breeding.In spite of the availability and extensive use of commercial synthetic acaricides,the repeated use of the chemicals has caused the development of resistance,unwanted activities on non-target organisms and environmental pollution.These problems emphasize the need for the development of new strategies for selective acaricides that are biodegrade to nontoxic products and have no effects on non-target organisms and the environment.Therefore,recent studies have focused on materials derived from plants oil as potential mite control products.Cinnamomum cassia and Syzygium aromaticum are traditional Chinese medicines and natural food spice.The use of the two plant essential oils to control mites meets the development needs of the times.In this paper,two kinds of essential oils,which showed high activity of acarid against T.putrescentiae and S.berlesei,from the two plants,C.cassia and S.aromaticum,were selected from 81 plant essential oils.The fumigation and contact toxicity of the two essential oils were studied by bioassay.The mechanism was preliminarily explored by means of morphological changes and determination of the changing trend of some important enzyme systems in the mites in order to provide a theoretical basis for the development and utilization of plant-based pesticides.The main results are as follows:1 The acricidal and insecticidal activities of 81 plant essential oils in different concentrations were determined by means of fumigation and contact simultaneously.24 plant essential oils with acaricidal activity and 20 plant essential oils with insecticidal activity were selected.18 kinds of plant essential oils were identified to have the acarid activity but no killing activity to economic insect E.sinensis.The toxicity of C.cassia and S.aromaticum oil was the highest.2 Adults of T.putrescentiae and S.berlesei were treated with the cinnamon oil,C. cassia oil,and its effective constituent cinnamaldehyde by using direct contact and vapour phase toxicity bioassays,comparing with treatments with the acaricides benzyl benzoate and dibutyl phthalate.Based on LC50 values in filter paper fumigation and contact toxicity bioassays,the acaricidal activities of C.cassia oil(1.06 μg/cm2)were 9.08 and 33.76 times more effective than benzyl benzoate and dibutyl phthalate;the acaricidal activities of cinnamaldehyde(1.36 μg/cm2)were 7.08 and 26.31 times more effective than benzyl benzoate and dibutyl phthalate.To adults of S.berlesei,the acaricidal activities of C.cassia oil(2.18 μg/cm2)were 8.63 and 31.63 times more effective than benzyl benzoate and dibutyl phthalate;the acaricidal activities of cinnamaldehyde(2.45 μg/cm2)were 7.68 and 28.15 times more effective than benzyl benzoate and dibutyl phthalate.Compared airtight fumigation test and open contact with both mite species,cinnamaldehyde were much more effective in closed containers than in half open ones,indicating that the mode of delivery of these compounds was largely due to action in the vapor phase.The toxicity to eggs of T.putrescentiae and S.berlesei were examined by using vapour phase bioassays and compared with the acaricides benzyl benzoate.The acaricidal activities of cinnamaldehyde(13.33 μg/cm2)to T.putrescentiae eggs were 14.79 times more effective than benzyl benzoate.To eggs of S.berlesei,the acaricidal activities of cinnamaldehyde(18.10 μg/cm2)were 18.51 times more effective than benzyl benzoate.When the concentration of cinnamaldehyde was 2.46 μg/cm3,the repellence against T.putrescentiae was 77.67% and 18.67% respectively at the closed system and the open system.When the concentration of cinnamaldehyde was 4.92 μg/cm3,the repellence against S.berlesei was 89.25% and 21.65% respectively In the closed system and the open system.The repellence was concentration-dependent.3 The toxicity of E.sinensis oil and Eugenol to adults of T.putrescentiae and S.berlesei were examined by using direct contact and vapour phase bioassays and compared with the acaricides benzyl benzoate and dibutyl phthalate.Based on LC50 values in filter paper fumigation and contact toxicity bioassays,the acaricidal activities of E.sinensis oil(4.82 μg/cm2)to adults of T.putrescentiae were 2.22 and 7.42 times more effective than benzyl benzoate and dibutyl phthalate;the acaricidal activities of Eugenol(4.49 μg/cm2)were 2.14 and 7.97 times more effective than benzyl benzoate and dibutyl phthalate.The acaricidal activities of E.sinensis oil(9.36 μg/cm2)to S.berlesei adult were 2.01 and 7.37 times more effective than benzyl benzoate and dibutyl phthalate;the acaricidal activities of Eugenol(8.16 μg/cm2)were 2.31 and 8.45 times more effective than benzyl benzoate and dibutyl phthalate.Compared airtight fumigation test and open contact with both mite species,Eugenol were much more effective in closed containers than in half open ones,indicating that the mode of delivery of these compounds was largely due to action in the vapor phase.The toxicity of E.sinensis oil and Eugenol to eggs of T.putrescentiae were examined by using vapour phase bioassays and compared with the acaricides benzyl benzoate.The acaricidal activities of Eugenol(32.78 μg/cm2)to eggs of T.putrescentiae were 6.01 times more effective than benzyl benzoate.To eggs of S.berlesei,the acaricidal activities of Eugenol(38.89 μg/cm2)were 8.62 times more effective than benzyl benzoate.When the concentration of eugenol was 4.92 μg/cm3,the repellence against T.putrescentiae was 85.84% and 21.53% respectively at the closed system and the open system.When the concentration of eugenol was 9.84 μg/cm3,the repellence against S.berlesei was 75.69% and 18.86% respectively in the closed system and the open system.The repellence was concentration-dependent.4 According to Stereomicroscope images,the adults of T.putrescentiae and S.berlesei treated with cinnamaldehyde are yellow and brown,the eggs of T.putrescentiae are yellow and shrink;the adults of Control group are colorless,the eggs of Control group are colorless and full.According to SEM images,the external morphology of T.putrescentiae and S.berlesei treated with cinnamaldehyde were uneven;the adults of Control group are smooth.According to TEM images,after treated with cinnamaldehyde the morphology of the epidermis body wall of T.putrescentiae was loose and the epidermis had flocculent attachment,no type I cells of the body cavity were found in this area,Nuclear Nucleolus and Perinuclear Chromatin of the experimental group are destroyed and blurred;The epidermis body wall of the Control group visible undulating,type I cells of the body cavity are intact and clear.Nucleolus,Chromatin,Mitochondria,Rough Surfaced Endoplasmic Reticulum,Smooth Surfaced Endoplasmic Reticulum and Perinuclear Chromatin of the Control group were clearly visible.5 Treatment after by cinnamaldehyde,the SOD and Ach E activities of T.putrescentiae and S.berlesei were varied with the concentration of cinnamaldehyde.Along with the extension of treatment time increased the activity at first and then a downward trend.But the all performance of the activity by the cinnamaldehyde treated lower than that of the control.Treatment after by cinnamaldehyde,the CAT and NOS activities of T.putrescentiae and S.berlesei were varied with the concentration of cinnamaldehyde.Along with the extension of treatment time increased the activity at first and then a downward trend.But the all performance of the activity by the cinnamaldehyde treated higher than that of the control.Treatment after by cinnamaldehyde,the GSTs activities of T.putrescentiae was varied with the concentration of cinnamaldehyde.Along with the extension of treatment time always increased the activity,those of S.berlesei increased along with the activity at first and then a downward trend.But the all performance of the activity by the cinnamaldehyde treated higher than that of the control.The results showed that cinnamaldehyde and eugenol had good fumigation effects on both tyromite and adult mites and their eggs,and both of them had obvious resistance to adult mites.Morphological observation showed that their action mode was related to destroying the epidermis and affecting the main protective enzymes in mites.These results are the theoretical innovation of the prevention and control of T.yrophagus putrescentiae and S.berlesei,and lay a foundation for the development and utilization of pollution-free acaricides. |
PDF Full Text Request