| The tomato leafminer,[Tuta absoluta(Meyrick)],is a devastating migratory pest that feeds on a variety of plants,especially Solanaceae plants.The damage is mainly caused by larvae feeding on leaves.Tomato leafminer was first detected in Ningxia in 2021,posing a threat to the tomato industry in Ningxia.Its morphological characteristics,biological habits,occurrence characteristics and control techniques have not been studied.In this paper,the morphological characteristics and biological habits of each stage of tomato leaf miner were studied by indoor feeding,aiming to lay a preliminary foundation for the identification and control of tomato leaf miner.In addition,the occurrence regularity and damage of tomato leafminer in Ningxia were preliminarily clarified through field investigation and monitoring.The indoor toxicity of 12 different insecticides to tomato leaf miner was determined.On this basis,the field control effect evaluation test was carried out,and the insecticides for controlling tomato leaf miner were screened.At the same time,the trapping effect of color plates with different treatments and suspension densities on the adults of tomato leaf miner was evaluated The test results are as follows:1.The morphological characteristics and biological habits of tomato leafminer.In order to clarify the morphological characteristics,developmental duration and living habits of tomato leaf miner,the larvae and adults were fed with fresh tomato leaves and 5%honey water,respectively.The growth and development of tomato leaf miner were observed and recorded under the conditions of temperature 28℃,humidity 40%,photoperiod L//D=16//8 and illumination 6000 lx.The results showed that the average generation time was 46.11 d,and the average duration of egg,larva,pupa and adult was 5.15,14.21,6.50 and 20.25 d,respectively.The larvae have 4 instars,which can be distinguished by body length,body color and other characteristics.The adult has the habit of day and night,and does not like the strong light environment.The female likes to lay eggs on the new leaves;the short-distance movement of larvae is mainly completed by spinning,and they prefer to pupate in places such as soil surface.2.Occurrence and damage of tomato leafminer in Ningxia.In order to preliminarily clarify the occurrence and harm of tomato leafminer in Ningxia,the occurrence regularity and harm of tomato leafminer in Ningxia were.preliminarily proved by field investigation and monitoring in Pingluo County,Yongning County and Shapotou District of Ningxia.The results showed that the occurrence of tomato leafminer in open field in Ningxia increased with time.The occurrence of tomato leafminer in open field in Ningxia could be roughly divided into three stages.The first stage was from June 1 to June 29.The number of each stage increased,but the rate of increase was relatively slow.The second stage was from June 29 to July 6,the number of each stage decreased.The third stage is from July 6 to August 17,showing an increasing trend and the growth rate is faster than the first stage.After August 17,the number of various stages of tomato leafminer decreased.The damage of tomato leafminer in Ningxia showed a continuous increase except that the fruit-boring rate index decreased on August 3 and August 24.The number of insect channels increased from 1.07 to 139.57.The fruit decay rate increased from 5.2%to 8.2%,decreased to 6.7%on August 3,and decreased to 5.9%on August 24.The leaf damage rate increased from 0.8%to 88.1%.The occurrence regularity of greenhouse tomato leafminer adults in Yongning County and Shapotou District in different regions of Ningxia is basically the same,which can be divided into three stages.The first stage of Yongning County is from March 14 to March 21;the second stage is the increase in the number from March 21 to April 21;the third stage was from April 21 to May 6,and reached a maximum of 252.41 on May 6.Compared with the growth rate of the three stages,the third stage increases the fastest,followed by the first stage,and the second stage increases the speed.The first stage in Shapotou District was from March 5 to March 10,and the number of tomato leafminer adults increased.The second stage is from March 10 to March 21,and the number decreased;the third stage was from March 21 to April 29,the number increased and the growth rate was faster than the first stage.The number of insects reached a maximum of 18.33 on April 29.The population began to decline after April 29.3.Evaluation of trapping effect of different treatments and suspension density on tomato leaf miner.By hanging color plates with different treatments in the field,the test results showed that the 7-day maximum trapping amounts of blue plate,yellow plate,blue plate plane trap and yellow plate plane trap to tomato leaf miner were 69.6,8.6,447 and 377,respectively.The trapping effect of blue plate is better than that of yellow plate,and the trapping effect of blue plate plane trap is better than that of yellow plate plane trap.By hanging different density color plates in the field,the trapping effect of 40 pieces/hm2 was the best,the trapping effect of 30 pieces/hm2 was in the middle,and the trapping effect of 20 pieces/hm2 was the worst.It is recommended to hang 40 pieces/hm2 blue plate plane trap in actual production.4.Indoor toxicity determination and field control effect evaluation of 12 different insecticides on tomato leafminer larvae.In this experiment,in order to screen out the agents with better control effect on tomato leaf miner larvae in actual production,the tomato leaf miner larvae were used as the research material,and the indoor toxicity determination and field control effect evaluation of 12 different agents were carried out by leaf dipping method and spray method.The results showed that the LC50 value of 2%emamectin benzoate EC was 0.0468 mg/L.At the same time,6%abamectin·chlorantraniliprole SC,35%chlorantraniliprole WG and 60 g/L spinetoram SC showed extremely high insecticidal activity against tomato leaf miner larvae,with LC50 values of 0.0586,0.106and 0.225 mg/L,respectively.In the field control experiment,6%abamectin·chlorbenzoyl EC,60g/L spinetoram SC and 2%emamectin benzoate EC showed excellent performance.After the second application,the control effect reached a maximum of more than 90%,which were 92.46%,91.76%and 90.64%,respectively.Although the indoor toxicity of 35%chlorantraniliprole WG was strong,it did not perform well in field control.In the actual production of tomato,it is recommended to use 6%abamectin·chlorantraniliprole SC,60g/L spinetoram SC and 2%emamectin benzoate EC,which can be used in rotation with traditional pesticides to control tomato leaf miner larvae. |
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