Studies On The Occurrence Of Conopomorpha Sinensis Bradley And Its Key Control Techniques

It was reported that the damage characteristics of litchi fruit borer (Conopomorphasinensis Bradley), the relationship between development period of the pests and the period ofgrowth of host plants, as well as their injured loss and the control technique with pesticidesand the residue degradation dynamics of 2 insecticides used on longan were conducted. Themain results were listed as follows:1. The damage selectivity of C. sinensisThe famel adults preferred to lay eggs young fruits on litchi than on the longan. Thepests preferred to injure the Chuliang and Dawuyuan and their injured rate were higher, butlower on the late varieties such as Nation and Bailu on longan.There was significant difference that the distribution of the eggs and larvae of C. sinensisin different parts on litchi and longan. The eggs and larvae were only found on young leaves.They could be discovered on the expanding fruits, as the fruits growed up to mature, theycould be injured seriously by the pests as well.2. The effect on output and quality of fruits injured by C. sinensisThe both weight and the soluble solids content of fruits were decreased at degreecompare with non-injured fruits. The slip of weight of fruit was 0.13%～9.83%, while theslip of content was 1.33%-15.73%. The decreasing amplitude varied from different varieties.3. The correlation between the population density of the C. sinensis and the rate ofinjured fruits of host.The correlation between injured fruits and dropped fruits rate with the rate of viopositedfruits on young fruits period was significant respectively on Jizui litchi. Their correlativeequations were:Y_injured=-2.2038+0.3464X_{rate of vioposited fruits} (r=0.9098);Y_dropped=13.0748+0.4881X_{rate of vioposited fruits} (r=0.9800);The correlation between injured fruits and dropped fruits rate with the eggs per fruitswere significant on longan too. Their correlative equations were:Y_injured=-1.5586+6.6166X_eggs (r=0.9265);Y_dropped=13.9884+8.0856X_eggs (r=0.9869).However, their correlations were inapparent in the period of expanding fruits.4. The relations of between the growth and development period of the pest and thephonological phase of hosts. The research results of dynamic of population of litchi fruit borer in filed showed thatthere was a stable relationship between occurrence period of the pest and phonological phaseof host plants. The density of pupas of the pest was larger in the period from the middle tendays of May to the first ten days August. The peak of the pupas was occurred in July on litchiand in August on longan when the fruits were maturing.5. The key control techniques against C. sinensis with pesticidesThe results from laboratory tests showed that pesticides of Chlorpyrifos 480 EC,Abamectin-Phentriazophos 150 ME and Dimilimat 200 SC provid good control effect againstthe pests by dilutiing 1500 times, which adjucted mortality rate were from 80.38% to 84.16%,respectively; The results in field trial showed that Cyhalothrin, Chlorpyrifos.Cypermethrin,Dimilimat, Alphacypermethrin and Chlorpyrifos were efficiecy against the pests, thier controleffects were from 73.68% to 83.41%, respectively.The mixture1 # which mixed Laurocapram and essential oil A with Chlorpyrifospresented more effective, its control effect was 94.58% by diluting 1500 times, whichincreased 14.20 percent than Chlorpyrifos. Its LC₅₀ was 51.81 mg/L, and its toxicity was 2.33times as much as Chlorpyrifos. It showed conspicuous synergistic action. The control effectsof the mixturel # and the mixture of Laurocapram and essential oil A withAlphacypermethrin against C. sinensis in field trail were 87.58% and 85.83% when they werediluted 1500 times, respectively. The effectiveness was much better than the Chlorpyrifos andAlphacypermethrin. The results showed that the penetration enhancer of Laurocapram mixedwith essential oil A could increase obviously effectiveness6. The degradation dynamics of 2 insecticides used on longan fruitsThe residue degradation reaction of Cypermethrin was slow comparatively in longanfruits. Its degradation half life was 3.88d; and 0.95mg/Kg residue on Shixia longan fruitssurface at teenth day after spaying Cypermethrin100 EC at a dilution of 500 times. But it wasnot detected out in fruit flesh. The residue degradation reaction of Chlorpyrifos was fastcomparatively in longan fruits. Its degradation half life was 2.16d; and blow 1mg/Kg residueon fruits surface at fourteenth day after spaying Chlorpyrifos 480 EC at the dilution of 500times. The residue was detected out in fruit flesh, but lower. Considering both the MaximumRresidue Level (WRL) and its dosages in practice, it was advisable that the interval ofapplication of Cypermethrin was set at more than 10 days; Chlorpyrifos was set at more than14 days.