| Alligator weed(Alternanthera philoxeroides(Mart.)Griseb.)is an amphibious invasive plant originates from South America.Phytophagus flea beetle Agasicles hygrophila was introduced into China to inhibit the spread of alligator weed due to its high fecundity which has achieved remarkable effect.In this dissertation,the mating behavior of Agasicles hygrophila and the two-dimensional and three-dimensional structures of their reproductive systems were addressed by conducting the traditional optical microscope,the micro-CT and three-dimensional reconstruction technology.Morphology of male and female reproductive systems and their spatial position in abdomen were compared at different stages(before mating,during mating,right after mating).The research results try to provide the basic knowledge both in morphology and ethology to explain the successful strategy mechanism of reproduction.The main results are as follows:1 The mating behavior of Agasicles hygrophila: At the beginning of the mating process,the male quickly climbed to the dorsum of the female,slapped or stroked the female’s elytra with its foreleg,and adjusted the position to insert its aedeagus into the female genital chamber.During the mating process,the male’s aedeagus exited and entered repeatedly,and the number of cycles was random.The mating always happened in the daytime,and its peak time is in the range of 14:00-16:00,cycles varied from 1 to 9 times.According to our results,35.48% of these mating pairs only had one entry-exit process with an average of 45.73 minutes,47.67% of them that the time of aedeagus entered into and kept stayed in the female’s genital chamber took less than 20 minutes,32.26% of mating pairs which the total mating duration ranged from 30 minutes to 90 minutes.And the longest duration of the entry-exit process occurred at the last cycle,with an average of 63 minutes.The mating time increased with the number of entry-exit cycles,and the maximum was 202 minutes.It is speculated that the stable insemination behavior duration range from 45 minutes to 1 hour.2 The 3D reconstruction of male and female reproductive systems: The morphological characteristics of the male and female reproductive systems were obtained by combining anatomical images with the microCT and the three-dimensional reconstruction images.The male reproductive system is composed of internal reproductive system and copulatory organ.The internal reproductive system consists of testis,vas deferens,accessory gland and ejaculatory duct.The copulatory organ includes a bifurcated phallobase and the aedeagus which with an approximately rectangular sclerite at the apex.The internal sac is a cylindrical membranous structure,with two protrusions at the apex of its ventral side and an arc arch near the base.The female’s internal reproductive system includes a pair of ovaries,a pair of lateral oviducts,spermatheca,common oviduct,genital chamber(vagina)and accessory structures.The three-dimensional reconstruction of reproductive system shown in details during mating.After the aedeagus inserted into the female’s genital chamber,the sclerite which present at the apex of aedeagus,opened and stuck at the end of female’s abdomen,with the membranous internal sac everted,and the ejaculatory tube transported sperm into the aedeagus to allow the seminal fluid entered the female body.The spatial position of both male and female reproductive system changed after mating.The whole internal reproductive system of the male changed from the ventral side to the dorsal side,while the site of the ovariole of the female moved up and the position of the spermatheca was closer to the ventral side.The aedeagus and internal sac are smooth and without spines,which would not cause the damage to the female genital chamber during mating.Combined with the observation of mating behavior,the male did not force the mating behavior,while the female had almost no selective behavior to the male,which provided a strong support for the high fecundity of Agasicles hygrophila. |
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