| Aprostocetus fukutai is an egg parasitoid of Apriona germari. In the natural condition, the parasitization rate is 50%. The mechanism of the wasps for controlling pests was studied extensively by chemical ecology and behavior ecology. So the discrimination behavior, the kariomne of the host and the sensilla of the wasp were studied in this paper. The results as following:1 Parasitization, host location, recognition and discrimination behavior of Aprostocetus fukutai were studied and analyzed by Petri dish assays, consisting of three parts.(1)In the experience of the parasitization behavior, the result is that the parasitizing behavior of Aprostocetus fukutai consisted of main steps in temporal sequence: host-unit location; host-unit probing, which included probing by antenna and ovipositor of wasp; host-egg probing; oviposition; marking.(2) The behavior of host location, recognition and host discrimination were observed and investigated by choice tests.the odor of male and female of Apriona germari, the secretion of mouthpart, the ovipostion secretion, the faeces, the naked host eggs and twig with healthy host-unit were examined by host location of Aprostocetus fukutai. The result showed that there was significant difference only between the twig with healthy host-unit was and the control, and no differences between other six cases and their controls.In the choice test of the different twigs, the data showed that the twig with healthy host-unit (grooved twig with host-egg and secretion of Apriona germari) was more attractive to parasitoid than healthy or feeding-damaged twig.In the choice test of the different grooved twigs, the results revealed that the attractiveness of the twig with healthy host-unit was strongest among the three treatments of twigs (twig grooved only, grooved twig with host-egg, and, grooved twig with host-egg and secretion). It implied that the secretion from A. germari played an important role in host location and recognition of A. fukutai.In the examination of the parasitized host-unit and unparasitized host-unit, the data showed that the attractiveness of the parasitized host-unit to A. fukutai was significantly lower than the unparasitized one. It indicated that the marking pheromone was left on the surface of host-unit by A. fukutai after parasitization behavior finished, and the other individual of conspecific wasp could detect it in a mid- or short-range.(3) The behavior of host location and recognition were observed and examined in the non-choice tests.The healthy twig, feeding-damaged twig, empty-grooved twig, grooved twig with host-egg only and grooved twig with healthy host-egg and secretion were compared by host location and recognition, and it was showed that healthy twig is different to the other four cases and grooved twig with healthy host-egg and secretion is most different to the other cases. So we can conclude that all kairomone are on the concealed-grooved-egg twig, and the secretion of Apriona germari is very important to the host location and host discrimination.In the non-choice test, the wasp refused to oviposit on the parasitized host-unit. So we can get the conclusion that the marking kairomone is the evolutional thing of the wasp.The different age of concealed-grooved-eggs were compared by host recognition, and the conclusion is that the concealed-grooved-egg of two days old is most strong to alluring host recognition of parasitoid, and the kairomone of the period of validity is no long than 6 days.2 The infochemicals mediating host location, host recognition and discrimination of the parasitoid were studied, which consist of three parts.(1)The grooved host-unit and the faeces were extracted by hexane, dichloromethane, methanol, acetone and distilled water. The different extracts were examined by Petri dish assays. It was found that there are some infochemicals used for host recognition by the parasitoid on the grooved host-unit and the faeces, and these infochemicals can be melted in hexane, dichloromethane and methanol, and hexane is the best solvent for the infochemicals. But the activities of three kinds of extracts to the wasp were not significantly different in three-way choice tests(2) The kairomone were purified and isolated by silica gel colμmn chromatography, and the isolated liquid was detected by the host recognition and host location of A. fukutai. The resulted is that hexane is the best mobile liquid for silica gel collamn chromatography.(3)The marking pheromones were extracted by the different solvent. The result revealed that the dichloromethane is the best solvent.3 Antennal surface structure and ovipositor of A. fukutai was observed by scanning electron microscope. The result as following:(1) There are six types of sensilla on the surface of the wasp antenna, namely, finger-like sensilla, platcodeμm sensilla, trichoid sensilla, ampullaceous sensilla, chaetic sensilla and B(?)hm's bristle were found on the antennae of A. fukutai.(2) There are some pore sensilla on the ovipositor and some secretion in the pores. (3) In the same time, the sensilla differences between two sexes were compared, and the sensilla difference between A. prolixus and A. fukutai were compared too. The results showed that the type, number, and distribution pattern of the antennal sensilla were similar in the two species, but the differences between two sexes were significant. |
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