| Bactrocera dorsalis(Hendel)is one of the most important pests of fruits and vegetables in agricultural production.Facing the situation that the insect is invading many kinds of fruit trees in the north and posing a serious threat to the industry.Researchers in this paper through the investigation and laboratory testing between farmland the way of combining biology characteristics,growth in the field of B.dorsalis the demise of the dynamic change and lay their eggs on peach,apple and other fruit characteristics are studied,the purpose is to find B.dorsalis in taian on all kinds of fruit trees and change rule.Therefore,in view of the planting risks of main edible fruits in north China,it provides a theoretical basis for formulating effective countermeasures and prevention and control strategies.The main results of this study are as follows:1.The basic biological characteristics of B.dorsalis were studied through careful indoor feeding and observation.It was found that the adults of B.dorsalis could fly and feed in the laboratory environment under the appropriate conditions of light,temperature and humidity.Females lay eggs for about 10 days,with a period of 30 to 40 days.The oviposite tube normally retracts into the basal segment of the oviposite under normal natural conditions,exposing only the part of the needling process.Through observation,it was found that the egg-laying process of female ovipositor was mainly divided into three stages: resting state,pre-laying preparation state and egg-laying state.However,the development time of the insect larvae in different fruits varied,with the total time ranging from 5 to 14 days,while the pupal stage ranged from 10 to 14 days.Adults of this insect can emerge all day in the laboratory,regardless of time period.Meanwhile,from 08:00 a.m.to 10:00 a.m.is the peak period of emergence,and all the pupae on the same day will emerge within 2 to 3 days.2.Through the observation of taian orchard,it was found that B.dorsalis adult appeared in early June,and ended all activities in late November.There was a peak of activity in the middle of the five months,and the annual trapping time from larva to adult was as long as162 d.The onset of adult seaging of B.dorsalis in 2018 occurred in late August,with a peak in early September and an end in late September.Compared with 2018,the occurrence time of each stage of the adult B.dorsalis in 2019 is about a month later,and the peak period begins in late September,peaks in early October and ends in late October.However,in both years the emergence cycle was completed within a month.There was also a significant difference in the number of B.dorsalis in different orchards.The study and statistical data showed that the number of B.dorsalis was in order : Jujube orchard > Peach orchard > Apple orchard > Pear orchard > Pomegranate orchard.At the same time,the trees around the orchard and fruit wholesale markets and other places can also attract B.dorsalis adults.3.Meanwhile,the observation of peaches of different colors showed that B.dorsalis preferred to lay their eggs on the bright red peaches,followed by the yellow peaches,and the least favorite was the green peaches.There was also a significant difference in the amount of spawning in different varieties of peaches.The selectivity of the fruit was higher than that of the almond.The result was in order of Chuanzhongdao > Dajiubao > Daizong > Zhongpan 11.The results showed that the number of larvae produced by the fruit was only 13.17 per fruit in the flat medium of the fruit,while the number of larvae produced by the fruit was 56.83 per fruit in the spherical medium of the fruit.However,there was no correlation between the number of larvae in the fruit and the firmness of the flesh,soluble solid content and other factors,and there was a significant positive correlation between the number of larvae and the content of starch in the fruit,but a significant negative correlation between the number of larvae and titratable acid content.4.At the same time,observe B.dorsalis in a day of different varieties of apple visit times.The visit is mainly in the daytime,and there is a peak visit at noon and afternoon respectively.The overall visit frequency is in order: Fushi > Jinshuai > Xinhongxing.The order of the number of egg-laying on the female fruit was: Jinshuai > Fushi > Xinhongxing,and the order of the larva weight in apple fruit was: Fushi > Jinshuai > Xinhongxing.Analysis result shows that B.dorsalis in choice of apple lay their eggs and larvae growth were influenced by apple itself,a variety of features,the number of holes and lay their eggs on apple fruit with apple fruit starch content existed significant positive correlation,and is significantly negative correlation with fruit titratable acid,other female worm eggs with no significant correlation between the fruit quality.Under scanning electron microscope,the most tip of the oviposition of B.dorsalis was blunt,and the diameter of the upper end of the needling process was 40.12 meters,while the diameter of the most tip was less than 11.05 meters.Due to the crack size,fruit peel skin package of wax layer thickness,layer number of the skin cells will influence factors,such as B.dorsalis eggs,bagging of golden Marshall at the same time,the average surface crack length is 100.07 mum,width of 29.91 microns,were greater than the scale at the top of the ovipositor,therefore very suitable for the female insect B.dorsalis puncture and lay eggs.The Xinhongxing apple,with its thick skin and fewer cracks,is the second most unsuitable for spawning.5.As the main fruits in shandong include peach,apple and jujube,these three kinds of fruits are suitable for the growth of B.dorsalis.Based on the occurrence of various conditions in farmland and the evaluation of female egg-laying selectivity,the researchers found that middle and late ripening peaches and fushi apples were at greater risk of being harmed by B.dorsalis,and it was necessary to strengthen the quarantine monitoring of these fruit trees and take comprehensive measures to carry out unified management and management. |
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