Font Size: a A A

Studies On Controlled Release Characteristics Of Sex Pheromone Components Of Dendrolimus Spp.(Lepidoptera: Lasiocampidae) From Microcapsule Dispensers

Posted on:2017-08-16Degree:MasterType:Thesis
Country:ChinaCandidate:X L LiFull Text:PDF
GTID:2323330503488731Subject:Agricultural Entomology and Pest Control
Abstract/Summary:PDF Full Text Request
Pine caterpillar moths, Dendrolimus spp., are devastating defoliators of coniferous trees in China. The moths are mainly distributed in Xinan, Huanan, Huazhong and other places, especially in Xinan and Dongbei region. Generally can be divided into the abrupt happening and accidental disaster and no disaster area, and main harm conifer and broad leaved tree species. When abrupt happening, killing large pine forest, causing severe damage to forestry production. Biological control using the specificity of the pheromone, overcome the pollution problem caused by chemical control, so using pheromone prevention to control pine caterpillar moths have unique role. In this study, the release rates of four major Dendrolimus microencapsule sex pheromone components were investigated under laboratory conditions, explored the different wall materials and core-wall mass ratio microcapsules the effects of physical and chemical properties and release characteristics. Simultaneously, according to the effect of different wall material concentrations of the pheromone components for cladding rate, retention and isomerization rate and release rate, etc, and monitored and evaluated the different lure trapping effect in the field, and researched on the release rates of four types of insect semiochemicals from four dispenser types. It provides a new tool for forest forecasting, which will provide a scientific basis for prevention and green control and technical support. 1. Controlled Release Characteristics of Sex Pheromone Components of Dendrolimus spp.(Lepidoptera: Lasiocampidae) from Microcapsule DispensersMicroencapsulation formulation technology was employed in order to develop effective lures that uniformly and persistently release Dendrolimus spp. pheromone components. Microcapsules loaded with synthetic Dendrolimus pheromone components, such as(5Z,7E)-dodecadien-1-ol and(5Z,7E)-dodecadienal, were prepared by suspension polymerization with methyl methacrylate(MMA), methacrylic acid(MAA), and styrene(St) as wall materials, and polyvinyl alcohol as dispersant. Pheromone-loaded microcapsules were characterized by optical microscopy and scanning electron microscopy. Nano-scale measuring software was used to analyze microcapsule sizes. The encapsulation efficiency, retention rate, isomerization rate, and release characteristics of the pheromone components in or from the microcapsules were also evaluated by gas chromatography. These analyses indicated that the average diameters of pheromone loaded microcapsules were in the range of 40-160 ?m, with the encapsulation efficiencies >87%, and retention rates of 50% over the 50 d exposure period. The pheromone release rates depend on the type of wall materials and core-wall mass ratios, with MMA being the best wall material for controlled release, followed by MMA-MAA and St-MMA, whereas 1:2 core-wall mass ratio was more consistent for pheromone release than those of 1:1 and 2:1 ratios. Our results showed that sex pheromones of the pine caterpillar moths could be encapsulated efficiently with high yields. 2. Microcapsulating and Controlled Release Characteristics of Sex Pheromone Components of Dendrolimus punctatus Walker(Leopidoptera: Lasiocampidae)Microcapsules loaded with synthetic D. punctatus pheromone components, such as(Z,E)-5,7-dodecadienol(Z5,E7-12:OH),(Z,E)-5,7-dodecadienyl acetate(Z5,E7-12:OAc), and(Z,E)-5,7-dodecadienyl propionate(Z5,E7-12:OPr). To reduce oxidation and isomerization of above conjugat ed diene compounds,for encapsulation of pheromone, gelatin(GE) and acacia gum(AG) were used as wall materials to prepare microcapsules via complex coacervation in this study, and polyvinyl alcohol as dispersant. Pheromone-loaded microcapsules were characterized by optical microscopy and scanning electron microscopy. Nano-scale measuring software was used to analyze microcapsule sizes. The encapsulation efficiency, retention rate, isomerization rate, and release characteristics of the pheromone components in or from the microcapsules were also evaluated by gas chromatography. These analyses indicated that the average diameters of pheromone loaded microcapsules were in the range of 4-40 ?m, with the encapsulation efficiencies >83%, and retention rates of 59% over the 45 d exposure period. The pheromone release rates depend on the type of wall material concentrations, with 1% being the best wall material concentration for controlled release, followed by 2.5% and 5%. The capsules prolonged the release time of the encapsulated sex pheromone and enhanced the stability of sex pheromone. 3 Researches on the trapping efficacy of sex pheromone lures for the masson pine moth, Dendrolimus punctatus Walker in the fieldIn order to explore the release characteristic, it is necessary to evaluate the trapping effect of the active compounds in the different dispensers. Through the lure test, we microencapsulated the major synthetic Dendrolimus punctatus Walker sex pheromone components with particular attention to the effects of different wall materials and wall material concentrations of the pheromone components on trapping efficiency. The effect of both suspension microencapsule and complex coacervation microencapsule lures were more siginificant than gray rubber septum lure. In microcapsule suspension lures, the pheromone trapping efficiency depend on the type of wall materials, with MMA being the best wall material for activity of trap, followed by MMA-MAA and St-MMA. In complex coacervation microencapsule lures, the pheromone trapping efficiency depend on the type of wall material concentrations, with 1% being the best wall material concentration for activity of trap, followed by 2.5% and 5%. Thus, the microencapsule lures were the most suitable dispenser of synthetic sex pheromone in the application of sex pheromone for monitoring and controlling Dendrolimus punctatus Walker, MMA wall material in microcapsule suspension lure was the best choice and 1% wall material concentration in complex coacervation microencapsule lure was the optimum choice. 4 Researches on the release rates of four types of insect semiochemicals from four dispenser typesIn order to develop effective lures that can uniformly and persistently release biologically active semiochemicals in the field, it is necessary to determine the release rates of various insect pheromones and host volatiles from different types of commonly used dispensers after the active compounds are identified. In this study, the release rates of four common bark beetle aggregation pheromone components(ipsenol, ipsdienol, trans-verbenol and S-cis-verbenol), two major Dendrolimus sex pheromone components(Z5,E7-12:Ald and Z5,E7-12:OH), and two conifer host volatiles(S-(-)-?-pinene and R-(+)-?-pinene) from four different types of dispensers were investigated under laboratory conditions(temperature, 24-26 oC; relative humidity, 50~80%; wind speed, 300 mL/min) using dynamic headspace volatile collection method. The entrapped components on Porapak Q were extracted from sampling tubes with hexane and quantified by Gas Chromatography. Results indicated that ipsenol had higher release rates than ipsdienol from the polyvinylchloride bubble cap dispensers over the test period, showing significant differences for both(+) and(-) enantiomers of ipsenol and ipsdienol on the 2nd, 22 nd, and 29 th days. Ipsenol and ipsdienol released quickly in the first two days and gradually declined to the lower release level on the 15 th day, then increased sharply during days 15-36 with a peak of release rates at the day 36, but finally declined to a consistent low release level. The closed polyethylene(PE) tube dispensers(#730) did not release any Dendrolimus sex pheromone components(Z5,E7-12:Ald and Z5,E7-12:OH) and the open PE tubes released them, indicating that these two moth pheromone components can't penetrate the 1 mm thick PE wall. The release rates of these two conifer host volatiles, S-(-)-?-pinene and R-(+)-?-pinene from the PE bottles varied over the whole testing period; with ups and downs during the earlier test period, reached the peak between 2 to 4 weeks after the start, and maintained at low level after the 43 th day. The release rates between these two components on the 15 th and 29 th days were significantly different, even though the differences in their overall average release rates were not significant. Release rates of trans-verbenol and S-cis-verbenol from PE pouch maintained a relatively low level during the first two weeks, then increased sharply to a peak on the day 36 for trans-verbenol or the day 43 for S-cis-verbenol, and then dropped to and maintained at a low level after their corresponding peaks. trans-verbenol showed significantly higher release rates than did S-cis-verbenol throughout the testing period except at the day 43. Studies of these release patterns of different semiochemicals from different types of dispensers could help us understand the dynamic releasing characteristics of various volatiles in the field, and their potential effects on the semiochemical-based monitoring and control efficacies. Finally, these results can provide some critical information on the selection of optimal dispensers for different semiochemicals in the pest control program.This study for the first time in a different way for pine caterpillar moths sex pheromone microcapsule was prepared, and sex pheromone were studied from different angles on the characteristics of physical and chemical properties and enrich the study of sex pheromone pest control and provide a new tool for monitoring, trapping and mating disruption.
Keywords/Search Tags:Dendrolimus, microcapsules, sex pheromone, release rate, trapping efficacy, dispenser
PDF Full Text Request
Related items