Abstract: To study the effects of oviposition secretion on microenvironment of ovipositing incisions in Apriona germari, the influence of oviposition secretion on water content, pH level and microbial quantity was analyzed by artificial inoculation of paper mulberry (Broussonetia papyrifera) trunk caged in the field and imitated incisions. The results showed that the daily water content of the imitated incisions within 4 d after eggs being laid was significantly lower than that of CK (P<0.05), while the water content of the imitated incisions beyond 4 d after eggs being laid was higher than that of CK. The diurnal variation of water content in the ovipositing incisions was similar to that of CK. Within 5 d after eggs being laid, the diurnal variation of pH values of the barks with an ovipositing incision and the barks with an imitated incision was similar to that of common barks. Beyond 5 d after eggs being laid, the pH values of the barks with an ovipositing incision and that of the barks with an imitated incision were higher than those of common barks. But there was no obvious difference in pH value between the barks with an ovipositing incision and with an imitated incision at the same day after eggs being laid (P>0.05). The bacterial quantity of the barks was compared among imitated incisions, ovipositing incisions and CK. The results showed that at 2 d after eggs being laid, the bacterial quantity of the barks with an imitated incision was significantly (P<0.05) higher than that of the barks with an ovipositing incision or that of the common barks. At the day of eggs being laid and at 1, 6, 7, and 8 d after eggs being laid, the bacterial quantity of the barks with an imitated incision was extremely significantly (P<0.01) higher than that of the barks with an ovipositing incision or that of the common barks respectively. At 3 d after eggs being laid the bacterial quantity of the common barks (1 320.0±189.0) was extremely significantly (P<0.01) higher than that of either the barks with an ovipositing incision or the barks with an imitated incision. At 4 d after eggs being laid, the bacterial quantity of the barks with an imitated incision was higher than that of the barks with an ovipositing incision (P<0.05). There was no significant difference in bacterial quantity between the every two of the three kinds of barks at 5 d after eggs being laid (P>0.05). These results suggest that at the prophase of embryonic development, the secretion has the ability of keeping water content of the ovipositing incisions to a certain extent, and does not influence the pH values of the barks containing an ovipositing incision, but the bacterial quantity in the ovipositing incision is inhibited by the secretion.

Key words: Apriona germari, oviposition secretion, ovipositing incision, water content, pH value, bacterial quantity