| Orthosia songi Chen et Zhang is one of the most important monophagous insect specifically feeding on Eucommia ulmoides leaves.Orthosia songi population outbroke in rescent years,and caused serious damages to Eucommia ulmoides industry.Gutta-percha is a natural polymer substituting for natural rubber,existed in the seeds,leaves and the skin of Eucommia ulmoides.The researchers found that gutta-percha could be isolated from the feces of leaf-eating insects after feeding eucommia bark,and also observed that obtained gum had higher purity and production,and better colour and lustre compared with the traditional extraction.This offers a new approach for the development and utilization of gutta-percha,and also provides a new idea to maximize the utilization and protection of eucommia ulmoides resource.Therefore,this study investigated the best condition of the O.songi in the lab,in order to provide theoretical basises for the large-scale artificial breeding and pests resource-oriented utilization.The main contents and conclusions were as follows.1.The results of artificial feeding: the larva had six instars,and the sixth instar larva had the longest developmental duration and was easy to distinguish by body colour.The larvae pupated in the soil,and the discrimination of male and female was easier to happen in pupal stage than the adult stage.2.The key techniques of artificial feeding:(1)Eggs could be saved up to 10 d at 4?,but their hatching rate could be significantly decreased after 10 d,and could not be hatched more than 12 d.The eclosion rate of female pupa reduced significantly after two months,while the male pupa showed the same tendency after two and half months.(2)The pupation and eclosion rates are higher in soil compared with the soilless environment,and certain humidity could increase pupation and eclosion rates.So,soil with certain humidity was the best condition for pupation.(3)Adult fecundity.Only when there were more than 6 male or female moths in the 5L container,mating and oviposition could be successful,but the eggs were in a low hatching rate on the whole.(4)Effects of temperature on development,ingestion and defecation of O.songi.The results showed the developmental duration decreased when the temperature increased from 18 to 30?,and the shortest developmental duration exited at 30? with 17 d.The development threshold temperature was 10.72 ?,and the effective accumulated temperature required for the whole generation was 670.37 degree-days.There was no significant difference with head width,body length and body weight of O.songi larvae with the temperature increasing in the range of 18~30?,but there was a significant difference with larval development(P < 0.05).The effects of the temperature and instar on the food consumption and defecation of O.songi larvae had a significant difference(P < 0.05),and food consumption and defecation increase with the growth of the larvae,both reaching a maximum in the final instar of larvae which reached about 70% of the total amount.3.Juvenile Hormone Analogue ZR-515 could prolong the larval developmental duration,gain weight and increase feeding amount and fecal excretion amount,but it would also significantly suppress the rate of pupation and adult eclosion,and lead to high mortalities of the larvae and pupae.With the concentration of hormone increasing,the effect is more obvious;When treated with 4th and 5th instar larvae,their subsequent growth and development could be obviously influenced;Considering the beneficial and adverse effect of hormone,1000ng/?L would be the best treatment concentration and 5th instar was the best treatment instar. |
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