| Alternanthera philoxeroides(Mart.)Griseb is a serious hazard of invasive alienweed, Agasicles hygrophila Selman&Vogt is one of the important natural enemiesused to control the weed worldwide. In Fuzhou, population of A. hygrophila wasdecreased rapidly in hot summer, this phenomenon affecting the biological control ofA.philoxeroides in summer. In order to clear the temperature of adaptive of differentgeographic populations, the local population and the tropical population, This paperstudies on the two geographic populations A. hygrophila of adaptive differences intemperature, and establishment of the population life table under18℃,25℃and32℃. Four main protective enzyme activities in vivo of A. hygrophila were tested atdifferent temperatures. The effect of the A. hygrophila on control of A. philoxeroideswas test in the field. It provides the basis information of bilcontrol of A.philoxeroides by using tropical A. hygrophila of Thailand population instead of thelocal population of Fuzhou in summer in China.The main results as follows:1. Differences of adaptability to temperature between different geographicalpopulations of A. hygrophila.The study shows that higher temperature is an important factor in restricting A.hygrophila population growth and reproduction. At18℃, the egghatchability,fecundity and adult survival rates of two populations were best among the threetemperature gradient. At25℃,egg hatchability and adult spawning volume of twopopulations decreased, while the food consumption of larvae, larval survival andeclosion rates increased. At32℃,the indexes except of female ration of F2for thethe two populations were significantly decreased. At18℃, the food consumption oflarval, fecundity and adult survival were significant differences between theThailand and the Fuzhou population. Thai population is greater than Fuzhou. At25℃, the food consumption of larval,fecundity of adults and female ratio of F2were significant differences between the two population. Thai population is greaterthan Fuzhou. At32℃, the food consumption of larval,larval survival and fecundityof adults were significant differences between the two population. Thai population isgreater than Fuzhou. The results show that the Thai population adaptive range oftemperature is superior to the local population.2. Characteristic of experimental population life table of A. hygrophila ondifferent geographic populations. The study shows that under the low(18℃) and the room(25℃) temperature, A.hygrophila population can rapidly grow and multiply. At high temperatures, lowsurvival rates of it, and rapid decline in population. At18℃, index of populationtrend of the Thai population is204.40, while the local population trend index is only134.21. Description of Thailand's population growth rate is faster than the localpopulation, the difference was significant. Biggest factor affecting the localpopulation growth rate was the percentage of the total number of spawning femalesup to the standard eggs,while Thailand is the female proportion. At25℃, the indexof population trend of the local population and the Thai population were209.10and248.54. Description of Thailand's population growth rate is faster than the localpopulation, but the difference was not significant. The biggest factor to affect thelocal and the Thailand populations' growth rate are female ratio. At32℃,the indexof population trend of the local population and the Thai population were0.81and2.58. The biggest factor to affect the local and the Thailand populations' growth rateare female fertility recession, the difference was significant.3. Different geographical populations of A. hygrophila protection of the enzymeactivities in response to temperature difference.A. hygrophila protection of enzyme activity varies with temperature changesand different protection of enzyme activity variation were not exactly the same. Asthe temperature increases, for the local populations: female CAT activity graduallydecreased, male to gradually rise. The POD activity of the female first rose and thendecreased, while the male is down then up. Female SOD activity for the first roseand then decreased, while the male is down then up. Both of male and femaleGSH-PX activities were first rose and then decreased. For the Thai population:female CAT activity first down and then decreased, male to gradually increase.Female POD activity gradually increases, while the male first rose and thendecreased. The SOD activities of the male and female insects were first rose and thendropped. Both of male and female GSH-PX activities were first rose and thendecreased. Studies have shown that the protection of enzyme activity at roomtemperature(25℃), with the exception of two populations of male POD there weresignificant difference, the other protection of enzyme activity were not significantlydifferent. Under low(18℃) and high(32℃) temperatures, the two A. hygrophilapopulations partial protection were significantly different. Overall, the Thaipopulation activity of protective enzymes is higher than the Fuzhou population, explaining its resilience to temperature greater than the local population.4. Different geographical populations of A. hygrophila control of Alternantheraphiloxeroides differences.Studies have shown that released density of A. hygrophila has an importantimplication for the control of A. philoxeroides. The Thai population is better thanlocal population to control the weed when realeased the same density(20/barrel-60head/barrel). It spends fewer three days to complete control of A.philoxeroides. However, if the release density is too large (more than80/barre). itwill be easily lead to population collapse (as the struggle intensified interspecific onthe late of100/barrel,appearing a large number of A. hygrophila deaths. On thecontrary, the length of time to completely control of A. philoxeroides, thus affectingthe control of A. philoxeroides.This study was defined two A. hygrophila geographic populations adaptabilityto the environment at different temperatures and reveals the Thai populationadaptability to the environment is better than the local population. The results fromthe research can provide the practical evidence to replace local populations withThai population to control of A. philoxeroides in China in summer. |
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