Studies On Population Dynamics And Control Of Bactrocera Dosalis (Hendel) In Pear Orchards Of Luxi County

Yunnan Province is one of the main pear production areas,and the damage of Bactrocera dosalis(Hendel)in Yunnan pear orchards has gradually increased since 2019,and the persistent damage of B.dosalis has been found in several pear orchards in Luxi County,Honghe,while the appearance of B.dosalis populations can threatened the yield and quality of pears.Nowadays,there are few reports on the damage and integrated prevention and control of the pear orchard,and it is especially important to conduct a systematic study on the occurrence and control of the pear orchard for the damage of the pear orchard in Yunnan area.In order to understand the occurrence of B.dosalis populations in pear orchards in Luxi County and the effect of different measures for its control.In this study,the population occurrence pattern of B.dosalis and the degree of influence of each factor in each orchard could be determined by monitored the population dynamics of B.dosalis and natural enemy insects,environmental temperature and humidity in three pear orchards in Luxi County,Yunnan Province.The daily occurrence pattern at the peak of its occurrence and the degree of influence of temperature and humidity on the daily activity of B.dosalis can be determined by investigation of the daily flight activity rhythm of B.dosalis and environmental temperature and humidity.It can be understood the insect community structure of the pear orchard by compare of the trapping effects of three different colors of sticky boards and sex attractants on male and female of B.dosalis,other pests,natural enemies and neutral insects in pear orchards,and to screen out the appropriate method.It can be finded out the types of insecticides and application concentrations for efficient control of B.dosalis by compare the toxic effects of three insecticides in pear orchards on the male adults B.dosalis in pear orchards.The purpose of this study is to find out the occurrence pattern of B.dosalis and the degree of influence of related factors,so as to determine the suitable time for control,meanwhile to screen out appropriate sticky boards and insecticides with good effect on B.dosalis and less influence on non-target insects.It could provide better guidance for the comprehensive control of B.dosalis in Luxi County.The main results are as follows:(1)The population dynamics of B.dosalis in three pear orchards,Longtanhe,Shanlinshao and Yanggehei,Luxi County,Yunnan Province were measured,was monitored from July 28-November 25,2022.The results showed that the high incidence of B.dosalis in Longtanhe pear orchard was concentrated in July-September,and the peak occurred in August 24-September 5;the high incidence of B.dosalis in two pear orchards,Shanlinshao and Yanggehei,was concentrated in September-November,and the peak occurred in October23-November 5 and September 26-October 8,respectively.It can be deduced that Longtanhe pear orchard B.dosalis control should be carried out before July,Shanlinshao and Yanggehei pear orchard should be carried out before September.(2)The effects of various factors on the occurrence of B.dosalis populations were analyzed respectively.The results showed that the environmental temperature and humidity were the main factors affecting the population dynamics of B.dosalis in Longtanhe pear orchard.The fruit development degree of Xuehua pear and Meirensu has a certain influence on the population dynamics of B.dosalis in the pear orchard of Shanlinshao and Yanggehei;Braconidae and Chalcididae have good control effect on the occurrence of all kinds of fruit flies,which has a greater influence on the population dynamics of B.dosalis in the pear orchard of Shanlinshao,followed by the two orchards of Longtanhe and Yanggehei.In addition,the application of insecticides in Shanlinshao and Yanggehei orchards,had a greater impact on the occurrence of B.dosalis populations dynamics.(3)We investigated the daily rhythm of fly activity at the peak of B.dosalis occurrence and analyzed the effect of environmental temperature and humidity on the activity of B.dosalis.The results showed that the dynamic model of the number of males captured was a two-peak curve,with two peaks recorded at 9:00 to 10:00 and 17:00 to 18:00,and troughs recorded at 12:00 to 14:00;environmental temperature and humidity were the more important factors affecting the daily fly activity of B.dosalis.It was negatively correlated with temperature and positively correlated with relative humidity.Indicate that the best time for the B.dosalis was at 09:00 or 17:00,and that the control of B.dosalis was weak at temperatures above 30 °C and humidity below 50 %.(4)The trapping effects of three colors of sticky boards on male and female B.dosalis,other pests,natural enemies and neutral insects in pear orchards were investigated.The results showed that the use of methyl eugenol significantly enhanced the trapping effect of different colors’ sticky boards on sexually immature males of B.dosalis,which showed the effect of yellow sticky board> green sticky board> blue sticky board,while there was no distinctive on the trapping efficacy of sexually mature males and females.The use of methyl eugenol in all colors of sticky boards reduced the trapping of neutral insects by about 69 %,while there was no effect on the trapping of natural enemies and pests.The highest benefit to harm ratio was found in blue sticky boards and green boards with water,and the lowest benefit to harm ratio was found in yellow boards with water and yellow and green boards with ME,which were 0.24,0.28 and 0.29,respectively,indicating that the use of yellow boards with methyl eugenol in pear orchards can effectively control B.dosalis while reducing the impact on other insects and effectively protect insect diversity.(5)We used by the film method to compare of the touch toxicity of three common insecticides against male adults of B.dosalis in pear orchards.The results showed that the LC50 of the male adults of B.dosalis to Emamectin benzoate,Spinetoram and β-Cypermethrin were 10.609(9.375-12.457)mg/L,23.329(16.736-50.838)mg/L and28.770(18.231-101.172)mg/L.It showed that Emamectin benzoate still had a better control effect on B.dosalis compared with Spinetoram and β-Cypermethrin.