| Rice leaffolder(RFL),Cnaphalocrocis medinalis Guenée,is one of the major insect pests,belonging to the genus Lepidoptera(Pyralidae),and is one of migratory pests with a wide geographical distribution,high adaptability to the environment.RFL larvae feed the leaves of rice plants with forming a roll of buds,cause damages to rice by mainly affecting the photosynthesis of rice leaves,and prevent the growth of rice plants resulting in rice losses.At present,rice varieties change fastly which may affect the occurrence of RFL.Furthermore,he frequent use of non-target chemical pesticides will also affect the population of RFL.We studied the effects of four different rice varieties and four different non-target chemical pesticides on the development and fecundity of RLF The effects of adjuvants on the control effects of Chloramphenicolamide against RFL in paddy field was also conducted.The main results are summarized below:1.The effects of different rice varieties the development and reproduction of RFL and their compensatory effectThe development and reproductive capacity of RLF feeding on four different rice varieties were observed.The results showed that the larvae and pupal duration of RLF feeding on Zhongzao39 was significantly shortened which was 21.2 ±2.6 d and 9.6±0.4d,respectively.The lowest of eclosion rate(57.14 ± 3.52%)and pupal weight(12.45±0.52mg/individual)of RFL was found on Zhongzheyou8 and Xushui134 respectively.And the lowest fecundity of RFL was also found on Xiushui134,which was 140.1±4.9 eggs/female.The highest chlorophyll content of the leaves of Xiushui134 fed by 5 RFL larvae for ten days was 20.15±0.05,however the activity of rice roots fed by RFL larvae for 5 days was 1.80 ± 0.10mg/(h.g),which is the highest.ZZY 8 was fed with 10 larval of C.Medinalis.,the highest chlorophyll content of rice leaf sheath was found on Zhongzheyou8 fed by 10 RFL larvae for 15 days,which was 4.50 ±2.80.The root activity of Yongyou 15 fed by RFL larvae for 5 days was highest,which was 13.90 ±0.40mg/(h.g).2.The effects of four different neonicotinoid pesticides on the development and reproduction of RFL were evaluated.The results showed that the larvae duration of RFL treated wity Pymetrozine by 1 time and 2 times were significantly shortened,and the pupal weight were also decreased.The larvae duration of RFL treated by Pymetrozine for 2 times was shortest,which was 17.6 ±0.3d.And the lightest pupal weight(16.67 ± 0.23 g/individual)of RFL was fed on rice plants treated with Nitenpyram for 1 time.There was no significant difference found on the fecundity of RFL treated by four neonicotinoid pesticides compared with the control.However,the number of unlaid eggs in the body and total number of eggs of female RFL increased significantly when RFL larvae was treated by the four insecticides.3.Effects of different auxiliaries on the control effect of Chloramphenicolamide against RFL Effects of different auxiliaries on the control effect of 20%Chloramphenicolamide against RFL in paddyfield.The results showed that compared with the control group,control effect of half proposed dosage of Chlorantraniliprole with auxiliaries Jijian was similar with the treatment of proposed dosage of Chlorantraniliprole.It meant that the dosage of chemical pesticides used for controlling RFL can be reduced when they were mixed with auxiliaries Jijian. |
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