| Objective: The internal structure and histology of Lasiohelea taiwana,Culicoides arakawai and Culicoides punctatus were studied by paraffin secting technique,which provided important basis for investigating the phylogeny and control of blood-feeding midge.Methods:1.Adult blood-sucking midges were collected by net sweep method,light lure method and human lure method,and the larvae blood-sucking midges were collected by the saturated saline method and the berlese funnel method.2.The larvae and adults of different periods were obtained by laboratory culture system of blood-sucking midges;3.Permanent specimens were prepared for classification and identification of blood-sucking midges;4.The internal structure and histology of L.taiwana,C.arakawai and C.punctatus were systematically studied by paraffin section and hematoxylin-eosin(HE)staining.Results: 1.Through the collection of Honghuagang District,Zunyi City,Huichuan District,Zunyi City,Zheng'an county,Zunyi City,and Daozhen County,Zunyi City.4298 adults,325 larvae,2 pupa of ceratopogonidae were obtained.At the same time,the laboratory breeding of blood-sucking midges was realized,53 eggs,29 larvae(17 larvae of first instar,6 larvae of second instar,4 larvae of third instar,2 larvae of fourth instar),2pupae and 1 adult female were obtained.2.Histological studies of the digestive system show: there were no differences between sex and species in digestive system histological structure of the three blood-sucking midges,which were all composed of digestive tract and salivary glands.The digestive tract is a pipeline through the body cavity of the worm,which is divided into three parts: foregut,midgut and hindgut.Crop is extremely developed,connected with the esophagus through a thin tube,with the role of food storage.The midgut is the most developed part of the digestive tract.According to the morphological characteristics,it can be divided into two regions,namely,the first and the second region of the midgut.The hindgut is divided from front to back into ileum,colon and rectum.The differentiation of ileum and colon is not obvious and difficult to distinguish,the anterior rectum bulges to form the rectal sac,inside which there are rectalpads.There are one pairs of salivary glands located near the esophagus above the forefoot of the chest.They are divided into main glands and accessory glands.The main glands play a secretory role and the accessory glands are the storage places of secretions.The digestive systems of L.taiwana larvae and adults were significantly different.In the larval stage,the foregut had a simple structure with mastic mouthparts,and the muscle tissue of the midgut was developed.The salivary glands were specialized into silk glands.At the adult stage,the silk glands disappear,the mouthparts change into a prickling and aspirating type,the larynx is specially transformed into a larynx pump with the function of feeding,the muscle tissue of the midgut is reduced compared with that of the larval stage,the intestinal wall becomes thinner,and the crop and rectal sac are formed.3.Histological studies of central nervous system show: the central nervous system of three species of blood-sucking midges and the larvae of L.taiwana were composed of brain and ventral nerve cord.The ventral nerve cord can be divided into three parts: the subpharyngeal ganglion,the thoracic ganglion and the abdominal ganglion.There was no significant difference in the structure of the central nervous system among the three species,and the brain could be divided into three functional regions,namely protocerebrum,deutocerebrum and sritocerebrum.The protocerebrum is connected to the compound eye to control the activity of the optic lobes,the deutocerebrum to control the activity of the antennae,and the sritocerebrum to process information from the body.Although the nervous systems of both larvae and adults of L.taiwana are chained with the same structure,the brain structure and the combination of ventral nerve cord were not completely the same,with significant differences.From the larval stage to the adult stage,the significant changes of the brain are the internal structure complex,in accordance with the longitudinal contraction of the worm body,the changes of the ventral nerve cord are mainly shortened and ganglion merger,leading to the shortening of the entire central nervous system.4.Histological study of respiratory system show: the three species of blood-sucking midges mainly relied on the tracheal system for respiration,and the tracheal system was all over the body without lung tissue.There were two pairs of valves in the thorax of the three species,which were located in the midthorax and the posterior thorax.The abdominal branchial sac tissue was tubular or vesicular,and the HE staining was not obvious.The respiratory system structure of L.taiwana larvae and adults was significantly different.The mature larvae had valves in every abdominal segment and prothorasum,but they had no function,and belonged to no-valve type or closed breathing.5.Histological study of reproductive system show: the female reproductive system of the three species of adult midges mainly consisted of four parts: ovary,oviduct,seminal vesicle and accessory gland.The number and morphology of seminal vesicles were significantly different among the three kinds of blood-feeding midges.One spherical seminal vesicle in female L.taiwana,one elliptical seminal vesicle in female C.arakawai,and two spherical seminal vesicles in female C.punctatus.The male reproductive system of three blood-sucking midges consists of four parts: testis,vas deferens,ductus ejaculatorius,and accessory gland.After HE staining,the testis had different shades of color inside,so it was speculated that different shades of color represented the different developmental maturity of sperm.the reproductive systems of juvenile and adult L.taiwana were also significantly different.In the larval stage,the ovary is located in the sixth abdominal segment of the female's abdomen and is oval in shape.The germ cells are evenly distributed in the ovary without obvious egg compartment and other structures.The end of the ovary is connected with an undeveloped narrow tube,and the tube develops in the adult stage.The testis is located in the 6th abdominal segment of the male's abdomen and is pear-shaped.The germ cells are evenly distributed in the testis,and the terminal part is connected with an undeveloped linear structure.In the adult stage,the linear structure develops into the vas deferens.6.Histological study of the sensory organs show: the compound eyes are the photoreceptor of the blood-sucking midges.It consists of several small eye surfaces,each of which is the inner membrane,cone cell,crystal and cornea from the inside out.Antenna is the sensory organ of blood-sucking midges,which can sense the humidity and temperature in the environment and produce corresponding chemical changes to search for food,blood source or habitat.The observation of tissue slices shows that there are a large number of neurons in the scape of antenna,which prove that it is very sensitive..Conclusion: In this study,an appropriate laboratory breeding system of blood-sucking midges was successfully established,and larvae and adults of different periods were obtained,which provided experimental materials for the future study of the growth and development of blood-sucking midges in different periods.For the first time,a set of paraffin sections and hematoxylin-eosin staining techniques were produced for the histological study of blood-sucking midges,and the digestive system,nervous system,respiratory system,reproductive system and sensory organs of blood-sucking midges were systematically analyzed using this technology.The structural features not only provide reliable support for phylogenetic development,but also provide an important basis for pest control.At the same time,it lays a foundation for future experiments such as gene mapping and immunohistochemistry.It not only provides reliable support for phylogeny and important basis for pest control,but also lays the experimental foundation for gene mapping and immunohistochemistry. |
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