| Pheropsophus occipitalis(W.S.MacLeay,1825)belonged to Coleoptera,Adephaga,Carabidae,Brachininae,Pheropsophus.The beetle has the most unique defense devices and functions of the entire class of insects which can use the chemicals and defense devices in its body to instantaneously generate a hot and poisonous chemical liquid and spray it at its attacker,with strange defense behaviors.In this study,P.occipitalis was taken as an example to help me to know its biological features clearly.Such as its morphological characteristics,biological habit,injection behavior,vocalization characteristics,and the microstructure of the defense system.This paper showed the unique defense activities and their possible functions of the beetle from five aspects: the identification of the P.occipitalis and its scientific issues,morphology and biology,the way it takes to defence,its structure and function,the research results and analysis,the problems and prospects.The following preliminary results were obtained:1.Biological characteristics of P.occipitalisThe length of P.occipitalis is about 14-21 mm,with overall black and yellow stripes.The male 7th stemite dehiscence,divided into left and right lobes,8th stemite is out.The female 7th stemite with medium groove,no 8th stemite,ovipositing flap exposed.In the natural state,they give birth once a year and the eggs evolved into adults after three or three instar larvae.Neither the adults nor the babies killed each other,but they were fond of darkness,dampness and aggregation.2.The position,morphology and ultrastructure of the defense glands of P.occipitalisThe location,morphology and ultrastructure of the defensive glands in the adults of P.occipitalis were found by optical,scanning electron microscopy and histology.The results show that the defensive glands of this species are posited on the pygidium,located at the dorsal side of the abdomen.According to the structure and function,they can be divided into collecting system,reservoir chambers,valve,reaction chambers and accessory glands,which are exists in pairs:(1)The collecting system is made by one collecting duct trunk,twelve collecting ducts,and a lots of secretory ducts and conducting canals;(2)The reservoir chamber is divided into the storage reservoir area and the flow reservoir area;(3)The flow of chemicals within the system is controlled by the interaction between the valve and the reservoir chamber capsule;(4)The difference between intersexual reaction chambers is discovered in size,length,fusion degree and internal microstructure;(5)The surface of the reaction chamber contains accessory glands rich in secretase;(6)The reaction chamber shows diversity in ultrastructure,with area-specific micropattern and as many as seven types of micro-pattern in the same body.3.The spray behavior and sound characteristics of P.occipitalisThere is no doubt that the spray behavior of P.occipitalis is extremely accurate.When spraying,it can quickly and accurately aim at the stimulated direction,quickly rotate the abdomen and adjust the spray posture.The initial spray "bomb" is also in the form of aerosol,with a fast speed and a wide coverage,ensuring accurate and effective spray.The short-time spray frequency of a single P.occipitalis is 5-14 times,and above 73% can spray more than 8 times for the first time,and all of them have the phenomenon of continuous spray.It takes 5 days to return to the original spray level after spray depletion.The spray behavior of P.occipitalis is like a pulse spray.The number of pulses varies from 3 to 15.The pulse interval is 18±3ms. |
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