| Bactrocera dorsalis(Hendel)is a worldwide citrus fruit pest,which seriously threatens the safety of citrus industry.In Guangdong alone,the annual loss caused by B.dorsalis can reach 200 million yuan.Because the females lay their eggs under the skin of the fruit,the adults are small and good at flying,and the control ability of tactile chemical pesticides on them is limited.Therefore,it is necessary to develop new prevention and control technologies to improve the control system of B.dorsalis.Under natural conditions,courtship and mating of B.dorsalis usually take place at dusk.The decreasing light intensity is an important condition for the initial courtship and mating behavior of B.dorsalis.Males release rectum gland compounds to attract females in the process of wing fanning courtship.Therefore,this study firstly systematically observed the basic rules of courtship and mating of B.dorsalis by behavioral technology,and systematically studied the regulation of light on this behavior.The pyrazine compounds(2,3,5-trimethylpyrazine: TMP;2,3,5,6-tetramethylpyrazine: TTMP)behavioral response rule;Finally,using the odor receptor co-receptor Bdor Orco mutant constructed in the laboratory,the differences in electrophysiological and behavioral responses of female worms of the wild type and mutant to two pyrazines were compared.The main results are as follows:1.The peak time of mating behavior of day-old adults was observed by using the high definition shooting system in the laboratory.It was found that the peak time of mating behavior of both group and single pair adults was 17:30-18:30.The specific wing fanning behavior of males was recorded systematically.The results showed that males began wing fanning at 6days of age and reached a peak at 9 and 12 days of age.Males(12 days of age)began flapping at 17:30 and reached a peak at 18:30 in a single day,and then the frequency of wing fanning behavior gradually decreased.But the frequency of wing fanning was significantly lower;The effects of light intensity on mating and wing fanning behavior were further systematically studied.The results showed that mating behavior usually occurred under low light conditions(50-1000 lux),while strong light(2000-30000 lux)significantly hindered mating.Wing fanning behavior was also regulated by light conditions.Basically consistent with mating behavior.In the absence of light(0 lux),the mating and wing fanning behavior of the male did not occur.2.The behavioral effects of TMP and TTMP on female worms were systematically observed using behavioral techniques.The results showed that the optimal dose of TMP and TTMP was 10 mg at different doses.The induced effective dose of TMP was 0.1 mg,and that of TTMP was 1 mg.When TMP and TTMP are mixed in a ratio of 1:1,the attractant effect is significantly stronger than that of TMP alone.The TMP and TTMP tendencies of female worms were significantly affected by rhythm.In the setting time,the reactivity time was mainly located at dusk(16:00-18:00),which was consistent with the mating behavior time,while in the daytime(8:00-16:00),there was almost no tendency to pyrazine behavior.Similar to the wing-fluttering behavior of males,light intensity also regulated the female’s tendency toward pyrazines.Strong light(10,000 lux)inhibited the female’s tendency toward TMP in the whole process,medium light intensity(2000 lux)delayed the female’s tendency toward TMP,while dark condition(0 lux)did not.3.Furthermore,the behavioral and electrophysiological responses of Bdor Orco mutants to pyrazines were compared between the mutant and wild-type females using behavioral and electrophysiological techniques.The results showed that in the absence of Bdor Orco,females almost lost their tendency behavior towards pyrazines.Meanwhile,the female mutant had weak responses to TMP and TTMP of 1 mg.To sum up,this study used behavioral techniques to study courtship and mating rules of adult B.dorsalis,further clarified the behavioral effects of two key proctoid gland compounds released by males on female,and preliminarily analyzed the molecular mechanism of pyrazine receptors in female bactyliae by combining the constructed mutant and electrophysiological techniques.It was found that light intensity could regulate the courtship and mating behaviors of B.dorsalis,especially the behavioral effects of females on pyrazine compounds.It was also identified that odor receptor co-receptors play an important role in proctoid gland substance perception.This study can provide reference for the development of new optical control technology and the improvement and development of behavior regulator. |
