| Diglyphus isaea Walker is an important natural enemy for controlling effectively agromyzid leafminers. Now mass rearing and large-scale application of Diglyphus isaea meet many troubles. Knowing more biological characters and the relationship of host plant-host- D. isaea will support the development of in vitro rearing of this kind of parasitoid. In this paper, the sensory receptors relationed with host location and discrimination were studied with scanning electron microscopy to lay the morphological foundation for knowing more biological characters. The role of host mines in the development of D. isaea was discussed in detail for the first time and preparatory research on mass rearing was did. The experimental results as follows:Nine distinct types of sensory receptors were present on the ovipositor, including B?hm's bristles, basiconic sensilla, trichoid sensilla, volcanic sensilla, styloconic sensilla, coeloconic sensilla, campaniform sensilla, short basiconic sensilla and cuticular spines. Eight distinct types of sensory receptors were present on the female antenna, including B?hm's bristles, sensory pore, uniporous trichoid sensilla, multiporous plate sensilla, basiconic capitate sensilla, thick-walled chemoreceptor, thin-walled chemoreceptor and trichoid sensilla. Two distinct types of sensory receptors were present on the female tarsi, including trichoid sensilla and campaniform sensilla. Their sensillar structure and their possible functions were analyzed and discussed in detail.The role of host mines in the development of D. isaea was discussed. There were more newly hatched larvae found their host larvae with the artifical mines'help than that without mines. Without mines, the mature larvae can't construct integrated pupal chambers with meconial pillars, but they can pupate and emerge successfully. The empty host mines can distinctly increase the attacked efficiency of D. isaea on Liriomyza sativae. Host mines worked as guide in finding host and lean in pupation in the development of D. isaea.The tested larvae in different artifical leaves were parasitized though the textures of host plant leaves (or host mines) and artifical leaves are very different. There was not special chemical substance on the boundary layer of host mines for locating host larvae. Female adults can also locate host larvae without chemical signals. At close range, vibrational signals transmited by the boundary layer of mines and emitted by the moving larvae are very important for host-finding. Chemical signals are not necessary for host-finding and oviposition. But chemical signals, even leaf juice odours of healthy host plant, can stimulate female adults of D. isaea to search host larvae more actively and increase the attacked efficiency on L. sativae.The third instar larvae of D. isaea were found to feed on housefly's larvae in feeding test. Besides, they can also feed on live host larvae and there is cannibalism among D. isaea larvae. That means host-specificity is not strict. But newly hatched larvae of D. isaea fed with dead larvae of housefly can survive to second instar at most. Analysis of nutritional components of larvae of L. sativae egg deposited showed that the content (g/100g fresh weight) of protein, fat, moisture, sugar and fucose was 6.615±0.250, 7.727±0.775, 68.366±0.485, 1.008±0.009 and 0.148±0.006 respectively. It is different from the nutritional components of housefly larvae, which is one of reasons of the death of D. isaea larvae. The nutritional component of host larva is one of signals used by female D. isaea for host location. The test of nutritional components of L. sativae larvae egg deposited lays foundation for artifical diet of D. isaea.
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