Study On Oviposition Selection Behavior And The Infact Of Light Factors Of Grapholita Molesta Busck

Grapholita molesta Busck is a worldwide pest of fruit trees.It mainly harms the young shoots and fruits of fruit trees of the rosaceae such as peaches,pears and apples by larvae,seriously affecting the yield and quality of fruits,and is one of the key factors restricting the cultivation of fruit trees with high quality and high yield in China.At present,chemical control is still the main method to control the larvae of G.molesta,supplemented by sex pheromone trapping and mesmerization to kill the male adults or interfere with the mating behavior of the adults,so as to achieve the purpose of reducing pesticide consumption.However,due to its drilling and hidden harm,it is necessary to use high frequency and large dose of chemical agents to achieve the expected prevention and control effect,which leads to serious pesticide residues and the enhancement of insect resistance and other subsequent problems.During the whole activity period of G.molesta,the short period of oviposition followed by the at the beginning of hatched larvae is the sensitive window period in the life cycle of many insect pests,which is the key to accurate pest control.To this end,this experiment accurately investigated the oviposition selection rules of G.molesta in the peach orchard,and analyzed the key factors affecting the oviposition selection behavior.The main research results are as follows:1.Field investigation found that G.molesta in the peach orchard showed obvious to specific parts of the oviposition choice behavior,female adults prefer to lay their eggs in the peach tree canopy top,accounts for over 80.00%of the total amount of spawning G.molesta oviposition selection have significant difference on different position leaves,overwintering generation,mainly lays its eggs on expanded leaf,oviposition rate was 93.33%.The first generation to the fourth generation preferred to lay eggs on the 1～15 leaves of branches,and the oviposition rate reached 80%.The rate of laying eggs on the 3～8 leaves of the first generation to the third generation was as high as 50.00%.In 2019.the oviposition distribution of the fourth generation was relatively scattered without obvious concentration,but in 2020,the oviposition location of the fourthg eneration was concentrated on 8～17 leaves,and the oviposition rate could reach more than 60.00%.There was also a significant difference in the oviposition selectivity between the front and the back of the leaves.Most of the eggs were laid on the back of the leaves,accounting for more than 95.00%of the total amount of oviposition.2.In the natural environment,through the investigation of microenvironmental heterogeneity.it was found that the light intensity of each part of peach tree crown was different,and the brightness of leaves was different in different leaf positions.According to the measurement of spectral intensity of each part of peach tree crown in peach orchard,the light intensity of upper and lower part of peach tree crown is obviously different at sunset,the upper part was significantly higher than the middle and lower part,and the periphery was significantly higher than the interior.There was no significant difference in the light intensity in the southeast,northwest and northwest of the interior,all of which were about 0.10-0.20 lux.The light intensity in the eastern part of the periphery was significantly higher than the other three directions.In the field investigation of the selection of G.molesta spawning,the spawning and non-spawning leaves of G.molesta were randomly refrigerated and brought back to the laboratory for reflectance spectra measurement,The results show that each leaf has similar reflectance spectrum,that is,the color is the same,the brightness is different.The measurement results of light intensity of each part of peach crown and reflectance spectrum of different leaves provide the basis for laboratory experiment.3.Brightness has an effect on the oviposition selection of G.molesta.Brightness contrast had no significant effect on the oviposition selection of G.molesta.In examining the effect of brightness contrast on the oviposition selection of G.molesta,set up four brightness contrast scenes,The background color is dark green,and the foreground color is light green;Light green as the background color,dark green as the foreground color;Light green and dark green are checkerboard;Light green and dark green are separated by a middle line,each half,the results show that G.molesta in have a background in brightness contrast of the oviposition,and no brightness contrast of the background of oviposition has no obvious difference,but in four brightness contrast on the background of oviposition is background color with light green,dark green for foreground lay their eggs in the background of choose the highest rate,as high as 51.27%.In the background with dark green as background and light green as foreground,the oviposition selection rate in the background was significantly higher than that in the foreground with light green as background.Under the background of checkerboard brightness contrast ratio.there was no significant difference in the oviposition selection rate under different brightness,but it was higher in the background of high brightness than in the background of low brightness.On the contrast background with light green and dark green split equally by the middle line,the background region with higher brightness is significantly higher than that with lower brightness.4.Light stimulation can affect the oviposition choice of G.molesta.In the dark state,the oviposition selection rate in the upper part was 72.50%,which was significantly higher than that in the middle part(16.48%)and upper part(11.02%).Under light condition(environmental light 100 lux),G.molesta Busck also preferred to lay eggs in the upper part,and the selection rate was 47.43%,which was significantly higher than that in the middle part(28.79%)and lower part(23.79%).When given light stimulation at the bottom(1001x light intensity),the lower part was preferred,and the oviposition selection rate was 72.1 7%,significantly higher than that at the middle(1 5.32%)and upper(12.51%)parts.