【作者】 李建成；

【导师】 张青文；

【作者基本信息】 中国农业大学 ， 农业昆虫与害虫防治， 2005， 博士

【摘要】 中红侧沟茧蜂Microplitis mediator(Haliday)属膜翅目,茧蜂科,小蜂茧蜂亚科,侧沟茧蜂属,是棉铃虫低龄幼虫寄生蜂。本论文在室内研究了中红侧沟茧蜂的生物学特性,筛选出粘虫为室内大量繁育中红侧沟茧蜂的替代寄主,建立了室内大量繁育中红侧沟茧蜂的工艺技术流程。并研究了人工繁育的中红侧沟茧蜂在新疆棉田扩散行为及田间释放对棉铃虫的控制效果,结果表明释放中红侧沟茧蜂可有效地控制棉田二代棉铃虫的危害,利用天敌昆虫对棉铃虫进行生物防治可作为新疆棉田害虫综防体系的一个主要措施。 1、中红侧沟茧蜂的寄生对棉铃虫幼虫取食量和发育的影响试验研究结果表明,中红侧沟茧蜂寄生明显降低寄主的取食量,被寄生的6日龄和8日龄幼虫较未被寄生的同龄期幼虫取食量分别减少75.4%和67.0%;被寄生的6日龄幼虫的取食量显著小于被寄生的8日龄幼虫取食量。被寄生后棉铃虫幼虫取食量和体重缓慢上升,到第8天至第9天其取食量和幼虫体重缓慢下降。中红侧沟茧蜂寄生能明显影响棉铃虫的取食行为,棉铃虫被寄生后在棉株上取食次数明显减少、静息时间增加、爬行时间减少、吐丝下垂时间减少。田间释放中红侧沟茧蜂在压低虫口基数的同时,可有效的控制当代棉铃虫的危害。 2、室内研究了不同日龄中红侧沟茧蜂成蜂对寄主幼虫龄期的选择、寄主被寄生时的龄期对寄生蜂幼期发育历期和茧重的影响。结果表明:当1-5龄幼虫同时存在时,该蜂可以寄生1-4龄寄主粘虫,不寄生5龄幼虫;偏爱寄生2龄和3龄幼虫,其寄生率高于对1龄或4龄幼虫的寄生率;对1、2、3和4龄幼虫的选择系数分别为0.21、0.31、0.27和0.21;寄主幼虫供寄生后,其寄生率随寄主幼虫供寄生时的龄期增大而下降。寄生于4龄寄主幼虫的蜂,其卵至结茧的历期显著长于寄生于2或3龄寄主幼虫的蜂,寄生4龄寄主幼虫所育出的茧重明显高于寄生于2龄或3龄寄主幼虫所育出的蜂茧茧重。随着雌蜂日龄的增加、寄生能力下降;但雌蜂日龄对寄生蜂子代卵至结茧的历期和茧重没有影响。 中红侧沟茧蜂对寄主棉铃虫大小有显著的选择性,主要寄生3龄棉铃虫幼虫以下幼虫,4龄以上棉铃虫很少被寄生。2-3龄棉铃虫幼虫为中红侧沟茧蜂的最佳寄生龄期。寄生时寄主幼虫龄期与卵-结茧期、茧蜂茧重、茧-成虫期、成虫羽化率和成蜂寿命之间存在相关性,寄生1龄幼虫其卵-结茧期明显长于寄生于2-3龄幼虫:随着寄生时寄主龄期的增加,后代的茧重明显增加,但是茧-成虫期的历期、成虫的羽化率以及成虫寿命没有差异,雌蜂的寿命稍长于雄性。 3、室内以6日龄粘虫作寄主研究了不同蜂密度对中红侧沟茧蜂寄生效能的影响,用1、2、4、6、8对中红侧沟茧蜂连续5日分别寄生50头粘虫幼虫,4对蜂和6对蜂处理粘虫的总出茧率最高,但平均每头雌蜂的出茧率却随蜂密度的增加而降低;在不同蜂密度的处理中后代茧重和羽化率没有显著变化;子代雌蜂的比例随寄生蜂密度的增加呈升高趋势。 4、在室内控温和田间罩笼条件下研究了温度和补充营养对中红侧沟茧蜂成虫寿命的影响。结果表明:随着温度的升高成虫寿命缩短,不同温度条件下成虫寿命存在显著差异;补充蜂蜜水能明显延长成虫的寿命;相同条件下雌虫寿命明显长于雄虫寿命。在18℃并饲喂10%蜂蜜水条件更多还原

【Abstract】 Microplitis mediator Haliday （Hymenoptera: Braconidae） is an abundant larval endoparasitoid of cotton bollworm Helicoverpa armigera （Lepidoptera: Noctuidae） in Hebei of China. The biology and mass rearing techniques of M. mediator were conducted in laboratory for producing large numbers of parasitoids efficiently. Mythimna separeta Walker （Lepidoptera: Noctuidae） was used as a host for mass rearing of M. mediator because H. armigera is cannibalistic causing it to be more difficult to rear. Basied on the biology of M. mediator the inundative release experiments were conducted in Xinjiang cotton field to evaluate the biological effects of M. mediator for conrol H. armigera. The results indicated that field release of M. mediator could be used effectively in managing H. armigera in cotton fields in Xinjiang.1、 Effects of parasitism by M. mediator on food consumption and development of H. armigera were evaluated in the laboratory. The results showed the significant difference in the food consumption of parasitized larvae and unparasitized larvae by M. mediator. The food consumption of the six-day and the eight-day instar of parasitized larvae were lower by 75.4% and 67.0% respectively than that of the six-day and the eight-day instars of unparasitized larvae. There are significant difference in the food consumption of the six-day and the eight-day instar of parasitized larvae. The food consumption of the six-day instar of parasitized larvae was less than that of the eight-day instars larvae. The food consumption and the weight of parasitized larvae slowly increased 8 or 9 days after being parasitized. M. mediator could suppress the population of H. armigera effectively and reduce the damage caused by the present generation cotton bollworm.2、 The preference of M. mediator for larvae of M. separata in different host instars and the host larval suitability for the parasitoid were investigated under laboratory conditions at constant temperature of 25 ± 1℃ and 65% ± 5% RH, 14:10 （L:D）h. When the parasitoid were exposed concurrently to host larvae in the 1^st to 5 instars, they could parasitize the 1^st to 4^th instar larvae, but did not parasitize the larvae in 5th instar; parasitism rates were higher for larvae in the 2^nd and 3^rd instars than in the 4^th and 1^st instars; the preference index of M. mediator for the host larvae in the 1^st, 2^nd, 3^rd and 4^th instar were 0.21, 0.31, 0.27 and 0.21 respectively; The host mortality after exposure were decreased with increase of the host age at exposure to the parasitoid. The parasitoid developed in the 4^th instar larvae had longer development period for the egg-cocoon stage and heavier cocoon weight than in the 3^rd and 2^nd instar larvae. The young M. mediator adults had larger parasitism capacity than the old ones. However, the wasp adult age had no significant effect on the development period for the egg-cocoon and the cocoon weight of the parasitoid in their offspring.3、 The effects of M. mediator wasp densities on the percentage parasitism were studied in the laboratory under controlled conditions. 6 days old L. separate larvae were used as hosts. Female M. mediator wasps were exposed at different densities of 1, 2, 4, 6 and 8 to the 50 larvae of L. separata. Totalparasitism was higher at 4 and 6 female M. mediator than other treatment, but the average parasitism of per female M. mediator decreased with the increase of parasitoid density. The cocoons weight and the adult emergence ratio had no difference in different parasitoid density treatments. The sex ratio （F: M） increased with the increase of parasitoid density.4> The effects of temperature and nutrition on the adult longevity of M mediator were examined in both laboratory and field cage experiments. The results indicated that adult longevity had significantly difference under different temperature conditions and decreased with the higher temperature. Honey water can effectively enhance longevity of wasps. The longevity of female wasps was longer than that of male wasps under the same conditions. The adults have the longest longevity of 15.4 d for female and 9.1 d for male in 18°C with 10% honey water supply and the shortest longevity of 1.1 d and 1.0 d in 38°C with no food supply. In field cage experiments the adult longevity was 5.2 d for female and 3.8 d for male in cages with no cotton plants and hosts and 7.6 d for female and 3.9 d for male in cages with cotton plants. After released in cotton field, the percentage cumulative mortality of M. mediator wasps was increased with the released days and reached 91.7% for female and 98.3% for male in the 8th day.5, According to the reproduce coefficient, parasitism to the host and mass rearing method, M. separata was selected as a host for mass-rearing of the parasitoid M. mediator. Comparing with other hosts of M mediator, M. separata is not cannibalistic and therefore economical to mass rear. The inducement and termination methods of diapause cocoons were studed in the laboratory and then the technic flow for mass rearing of M. mediator have been established to produce diapause cocoons continuous. The storage conditions of diapause cocoons and field release methods also have been definited.6, Studies on the dispersal directions and distance of M. mediator wasps in Xinjiang cotton field during the bud and boll stage were conducted in 2003 and 2004. The results indicate that the effective dispersal distance （EDD） of M. mediator was about 15 m and the maximal dispersal distance was 50 m. The wasps were favored to dispersal along the cotton plant rows. The dispersal direction of M. mediator in cotton field was related to wind spreed and direction, when the average wind spreed was lower （1 m/s） the main dispersal direction was up the wind and no difference among the eight directions.7> Field experiments and surveys were conducted in 2003 and 2004 to evaluate the efficiency of using the parasitoid M. mediator to control populations of H. armigera in cotton fields in Northwestern China’s Xinjiang Province. The population levels of the second generation H. armigera in Southern Xinjiang in 2003 and 2004 were ca. 20-60% above the economic threshold of this pest. The longevity of field released female and male parasitoids was 7.6 ± 0.4 d and 3.9 ± 0.4 d, respectively. Field tests showed that the number of parasitized H. armigera increased with an increasing number of M. mediator cocoons released in the field. The release of 2,250 or 15,000 laboratory-reared M. mediator cocoons per ha in cotton fields resulted in 38% to 61% parasitism of H. armigera in 2003, and 35% to 66% parasitism in 2004, respectively. The efficiency of the parasitoids varied considerably with different numbers of parasitoid cocoons and with the frequency and sites of release. However, the highest control efficiency in these studies was obtained with a single release of cocoons and the highest number ofrelease sites. Large-area releases of M. mediator in cotton fields of Shufu, Shule and Shache counties resulted in more than 60% parasitism and an 80% decrease in cotton boll and bud damage when compared with the control fields.更多还原