| Bemisia tabaci（Gennadius）is one of the most harmful pests on vegetables and flowers.It mainly caused decreased of the yield and quality of vegetables through sucking plant phloem sap to cause nutrient loss,secreting honeydew to induce "coal pollution disease",and transmitting plant viruses to cause plant virus diseases.In order to increase yield and quality of vegetable quality and reduce the economic losses caused by B.tabaci,a large number of chemical fertilizers and pesticides have been applied in China.Although the purpose has been achieved to a certain extent,the long-term excessive use of chemical fertilizers and pesticides has brought serious environmental pollution and increased drug resistance of pests.In the long run,it will lead to the decline of the safety of vegetable crops,damage the ecological environment and endanger human health.Therefore,Modern pest control management should be in accord with the concept of green control and strive to form a green pest control system.In this study,pepper were used as experimental materials to explore the control effects of several physical and biological measures such as entomopathogenic nematodes,Paecilomyces and blue light on vegetable B.tabaci.The results will provide a theoretical basis and technology for the implementation of green control of vegetable pests by non-chemical methods.The main results are as follows:1.The infection ability of entomopathogenic nematode to B.tabaci and its control effects on B.tabaci in the field were studied by using Steinernema carpocapsae and Xenorhabditis indica as materials.The results showed that under the condition whten the temperature was（28±2）℃,the relative humidity was（60±5）%and the back of pepper leaves was wet,the nematodes invaded in the nymphs of B.tabaci in about 4 hours and killed them within 2 to 3 days.There were significant differences in the control effects of different nematode varieties on B.tabaci nymphs.After 3 days of treatment,the mortality rates of B.tabaci old nymphs（3rd and 4th instar）and young nymphs（1st and 2nd instar）treated with S.carpocapsae were 14.82%and 23.09%higher than those treated with Xenorhabditis indica LN2 nematode,respectively.Different concentrations of nematodes had different control effects on nymphs of B.tabaci.The lethality rates of 22 IJs/mL,16 IJs/mL and 13 IJs/mL of S.carpocapsae All lines to the old nymphs of B.tabaci were 42.79%,34.74%,29.31%respectively,and to the young nymphs were 44.58%,41.66%and 39.61%respectively.The additive 5%d-limonene soluble solution can be used in combination with nematode,which has a promoting effect.When the nematode concentration was dilute to 22 IJs/mL and mixed with 1000 times of 5%d-limonene solution,the insecticidal effect is the best.The lethality rates of old nymph and young nymph were 60.61%and 61.55%,respectively.The amount of water sprayed on the leaf surface of pepper in the field has a significant effect on the control of B.tabaci.Under the conditions of spraying water of 1.5、1、0.5 L/m2,the corrected mortality rates of old nymphs were 66.49%,66.50%and 47.78%,respectively,and the corrected control effects of young nymphs were 69.30%,58.52%and 51.83%,respectively.In conclusion,spraying nematode has a certain control effect on B.tabaci,and the assistant 5%d-limonene can promote it.Keeping the surface of pepper leaves moist can improve the control effect on B.tabaci.2.The control effect of Paecilomyces on B.tabaci was studied by spraying different concentrations of Paecilomyces spore suspension on potted pepper seedlings and field cultivated pepper seedlings in incubator and outdoor field environment.The results showed that Paecilomyces had a good control effects on B.tabaci,and the corrected control efficiency on B.tabaci increased with the prolongation of Paecilomyces treatment time.When pepper seedlings were treated with 1×106 spores/ml of Paecilomyces,the corrected control effect on B.tabaci increased 39.34%on the 6th day compared with the 2nd day,and 18.33%on the 10th day compared with the 6th day.The control effect of Paecilomyces against B.tabaci increased with the increasing of Paecilomyces concentration.When treated B.tabaci with different concentration of Paecilomyces for 10 days,compared with 1 ×104 spores/ml treatment,the corrected control effect of 1×106 spores/ml Paecilomyces on the 2nd instar nymphs increased by 16.84%,while 1×107 spores/ml increased by 28.5%.Moreover,the corrected control effect of Paecilomyces treatment on young instar nymphs was significantly higher than that of older nymphs,and the corrected control effect of 1 ×107 spores/ml Paecilomyces cerevisiae treatment on second instar was 39.50%higher than that of 4 Instar nymphs.The control effect of Paecilomyces on B.tabaci was also closely related to humidity.When the treatment time was 8 d,the corrected control effect ratios of 80%humidity on the 2 instar nymphs of B.tabaci was 31.33%and 35.16%higher than that at 65%and 50%humidity respectively.In addition,the combination of Paecilomyces and insecticide imidacloprid can improve the control effect on B.tabaci,and the corrected control effect was up to 85.83%.The field control effects on B.tabaci showed an upward trend with the increase of Paecilomyces concentration and time treatment.For example,when the treatment concentration of Paecilomyces was 1×107 spores/ml,the corrected control effect against B.tabaci increased by 31%from the 2nd to the 10th day,and when the treatment time was 6 days,the control effect of 1×X107 spores/ml Paecilomyces was 64.66%and 25.83%higher than that of 1 × 104 spores/ml and 1 × 105 spores/mL,respectively.3.The control effects of physical treatment such as blue light on B.tabaci in the field and the field application technology of using light to repel insects were discussed.The results showed that the strongest repellent effect of blue light on B.tabaci was during the period from 18:00 to 19:00 from 17:00 to 22:00,and the reduction rate of insect population accounted for 50.94%of the total in the experimental period.The repellent effect followed was during 17:00 to 18:00 by 22.29%.Blue light showed a good repellent effect on B.tabaci on protected pepper.After 10 days of blue light treatment,the population reduction rate of B.tabaci on pepper reached 85.73%.There was no significant difference between the upper and middle leaves of pepper.The population of B.tabaci in the blue light treatment area was significantly less than that in the control area. |
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