| The breaks of Oxya chinensis had become increasingly serious in recent years along with the changes of the agricultural practices, ecological environments and the global climatic conditions. It is, obviously, very important to control population of the insect. To study the result and the mechanisms of porphyrin insecticides, we treated insect of different instar with ALA and PpIX in this paper.In natural light, when sprayed with 5-aminolevulinic acid on Oxya chinensis, within 7 days all treated males died while the controlled males only do so in half. However, in the lower concentration, the treated females are hardly affected. By analyzing PpIX and protein content with fluorescence spectra and Bradford, results showed that, compared with the controlled, the content of protein per gram tissue in male body decreased. But female's hardly decreased. The above results suggested that the effect of ALA is relation to the content of protein per gram tissue. In addition, compared with the controlled, the content of PpIX per milligram protein increased. Which partly coincide with the results of Contantin A. Rebeiz. The results suggested that PpIX content of per milligram protein is relation to the effect of ALA. In conclusion, it is the photosensitive toxin that results in the effect of ALA on Oxya chinensis.Under light and darkness, the effect of 5-Aminolevulinic acid (ALA) acting as insecticides on Oxya chinensis was investigated in the forth-instar larvae with different doses. The results indicated that, within five days, not only the average of molt but also mortality between the A treatment and the control were significantly different (p<0.05). While there were not significantly different between the C treatment and the control, and the B treatment were slightly different. Further mechanisms assay showed that the average of protoporphyrinIX (PpIX) of per miligram protein and total protein of per gram tissue were also significantly different (p<0.05) between A and CK treatments. The results of above suggested that, when administration withALA, at low dose such as C treatment, ALA-induced protoporphyrinIX higher than that of the control, which results in the increase of total protein degradation by oxidating protein, amino acid and soft-fatty acid from photosensitizer of PpIX under light. And at higher dose than C treatment as A treatment ALA-induced PpIX is lower than that of CK treatment. As a result, the content of total protein is higher than that of the control. Because the content of PpIX is lower than that of the control, which influence the balance of protein normal metabolism. So the content of total protein is higher than that of the control. Moreover, at much higher dose than A treatment as B treatment ALA-induced PpIX is much lower than that of CK treatment, which may further limit the protein normal metabolism. Thus the content of total protein is low greatly.When sprayed ALA or injected PpIX respectively on the fifth-instar larvae of Oxya chinensis in the artificial light, the results shown that there were significantly different between the treated with PpIX and the control (p=0.0489 and p=0.0343) in molting number and mortal number. While there were not significantly different between the treated with ALA and the control(p=0.0489 and p=0.0343) in molting number and mortal number(p=0.23 ^P p=0.14).At the same time, it is shown that both the PpIX content of per milligram protein and the total protein of per gram tissue were not different between the treated and the control. Analyzing from the above we can conclude that ALA might induce PpIX accumulate in the insect and the PpIX might have toxin on the insect in the artificial light.In conclusion, The object of the paper is to study the results and the mechanisms of ALA on Oxya chinensis administered in different conditions such as lights and doses as well as instar. In addition, in order to further study the mechanisms of ALA, we designed injected treatment with PpIX. The results indicated that both the average of molting number and the average of mortal number were significantly different between A treatment and the control when administered insect of the forth-instar with different doses of ALA in natural light (p<0.05). While B treatment and C treatment were...
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