译 名：
BIOLOGICAL STUDIES OF BRACON CREENI AND EXPERIMENTAL RESULTS OF HOST ALLUREMENT IN THE FOREST
作 者：
LIU CHUNG-LO;TSAI CHIEN-PING;WANG KING-YEN;WANG KING-TI Laboratory of Insect Resources,Institute of Zoology,Academia Sinica Lac Research Institute,Forestry Research Academy
摘 要：
Based on the studies of the biologies of Eublemma amabilis a lepidopterous preda-tor of the lac insect, and of Bracon greeni, a hymenopterous parasite of the moth larva,and on the results of host allurement experiments, the following conclusions seem appro-priate: 1. In view of the severe nature of injury due to Eublemma amabilis, the closecoincidence of its distribution with that of the lac insect, the secure shelter afforded itby the lac encrustation, the constant hazard of its spreading into new areas once vigilenceis relaxed at introduction, the effective control of Eublemma should become an order ofthe day in any effort at promoting lac production. 2. Although the enforcement of such measures as rigid selection of clean brood lac,persistent retrieving of empty brood lac from the trees, timely reduction of used broodinto seedlac will all have their respective effect in eliminating Eublemma, biological con-trol is nevertheless the only available means for destroying it while on the trees beforeharvest. 3. Observations indicate that under Yunnan conditions Eublemma passes through3 to 4 generations within the year and that these generations overlap. This offers asplendid opportunity for Bracon greeni to multiply and to overtake the host reproduc-tively. As a matter of fact, Bracon does have two generations against one of its host. 4. In relation to Eublemma, Bracon greeni is a polyvalent monoxenous parasite.Hence it is a most effective agent in reducing host density. Once thought to be mono-valent, Bracon greeni is now known to be able to develop in a number of fictitioushosts, and therefore can be readily mass-produced for field liberation. 5. Bracon greeni possesses high fertility (average of 113 eggs deposited), shortdevelopmental period (in May to June, a generation requires only 15.2 days), favorablefemale sex ratio (76:24), remarkable female longevity (when adequately supplied withnutrients, 99.9 days), high parasitization rate maintained even in later life (in the labora-tory two months after emergence, 65.1%; in the open, it effects a raise of 25% overthe natural rate), and is from all these considerations very well qualified as a biologicalcontrol agent of Eublemma. 6. As Bracon greeni parasitizes only the later stages of Eublemma larvae (bodylength attaining 3mm) and under a definite thickness of the lac encrustation (not over7mm), it is necessary to so time the liberation that there will be a maximum crop oflarvae of 5--6 mm in length and under a thickness favorable to the parasite. 7. Eupelmus tachardiae acts as a primary parasite of the lac insect and a hyper-parasite of the braconid. Its presence has already been recorded in China. Every effortshould be made to annihilate such as encountered. 8. Host allurement experiments show beyond a doubt that the more concentratedthe host is in an area, the higher the percentage of parasitization. When a shift is madefrom the current scattered type of lac cultivation to one of the plantation type, an in-crease in the effectiveness of Bracon greeni may be reasonably expected. 9. Due consideration should be given to the possibility of microbial control, sincea hundred percent kill of the Eublemma larvae has been registered in the experimentswith Bacillus thuringiensis var. thuringiensis by the Division of Insect Pathology, Labora-tory of Insect Resources, Academia Sinica.
