A Preliminary Sdudies On The Multiplication And Application Of Buzura Suppres Saria Nuclear Polyhedrosis Virus

Buzura suppressaria Guenee (Lepidoptera:Geometridae)(Bs) is a polyphagous pest, which could cause extensive damage to forest tree. Bs is one of the main pests of Eucalyptus spp., Vernicia fordii, Camellia oleifera, Cinnamomum cassia, Citrus, Loquat, Castanea mollissima, Persimmon spp., Mulberry spp., Myrica rubra and so on. At present, Bs has become one of the most important eucalyptus pests in Guangxi province.This paper systematically studied the key technologies of artificial rearing of Bs basing on its biological characteristics. Moreover, it preliminarily studied the multiplication and application technique of Bs nuclear polyhedrosis virus (BsNPV) according to the optimum breeding conditions of Bs. The main results as follows:1. It was found that there were no significant differences between Bs sampled from Luorong in Liuzhou and Tianlin in Baise on the indices of pupal size, pupal weight, emergence rate, mortality, fecundity and hatchability.There were also no significant differences between Bs from two places on the indices of body length, weight, head width and developmental duration after fed with mature leaves of Eucalyptus clones GL-UG9(E. grandis×E. urophylla). These indicated that Bs from two places could be used as the insect source of artificial rearing. 2. The4th instar larvae were fed with mature leaves of three kinds of eucalyptus clones (DH184-1:E. urophylla×E. camaldulensis, GL-WC3:E. urophylla×E. camaldulensis, GL-UG9:E. grandis×E. urophylla), but little differences had been found in its feeding amount, and no obvious feeding preferences. The results showed that these eucalyptus clones were Bs’favorite food. So we used eucalyptu clones GL-UG9as its food, and observed some of its biological charecteristics. It was found that larvae obviously preferred mature leaves and old leaves to tend leaves;the relative growth rate of the3rd-5th instar larvae fed by mature leaves slightly higher than that fed by old leaves; the efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) of larvae fed by mature leaves were relatively higher than that of larvae fed by old leaves. Therefore, mature leaves were the best food for artificial feeding of Bs.3. Bs larvae growth rate was measured at25℃to31℃, and the growth rate was the slowest at25℃and the highest at31℃. These indicate that there was a positive correlation between temperature and Bs larvae growth rate. However, the mortality of Bs larvae could up to80%at high temperature (31℃). Considering the growth rate and mortalily, its optimum temperature was27℃-29℃.4. The amount of proliferation of BsNPV was the largest in the5th instar larvae, which was161.9times larger than it in the2nd instar larvae,13.7times larger than it in the3rd instar larvae, and3.7times larger than it in the4th instar larvae. In the other word, there was a positive correlation between the amount of proliferation of BsNPV and the size of the polypide. But the amount of proliferation of BsNPV in the unit of body weight in each Bs instar larvae had no significant difference. So the4th or5th Bs instar larvae, would be the best host to produce BsNPV.5. The production of BsNPV were highest when proliferated at temperature of25℃, then30℃. And the yield per unit body weight was the smallest at temperature of35℃. These results suggested that temperature is one of the important factors affecting the proliferation of BsNPV.6. Within a certain range of concentration, the mortality of larvae increased with the concentration of BsNPV. However, at the same concentration of BsNPV, the mortality of larvae decreased with instar stage. So Bs would be more efficiently controlled by BsNPV before the3rd instar larvae.7. The preservation time would significantly affect the activity of BsNPV. The activity of BsNPV respectively decreased by5.45%and8.01%at room temperature one and two year later. The viability of BsNPV gradually reduced with the storage time extended.8. Different concentrations of BsNPV did not cause obvious pathological effect on the5th instar silkworm. This illustrated that BsNPV had significant specificity.