Effects And Mechanism Of Antiaphrodisiac Pheromone On The Mating Behavior Of Apolygus Lucorum

Mating is an important process in the reproduction of insects,which determines the continuation of insect population.The reproduction strategies of most insects in nature are polygyny and polyandry,which means that male or female insects can mate with multiple spouses in their lifetime.In the multiple mated insects,the male insects produce a variety of chemical compounds in their sperm,such as antiaphrodisiac pheromone,which will be transmitted to the females through copulation.These compounds can make the females lose their attraction to other males and stop mating in a short time,so as to reduce the competition of sperm.Studying the mating behavior and mating inhibition of insects,understanding the influencing factors of insects mating and reproduction,and controlling the number of their offsprings are of great significance for pest management.In this study,the mating behavior of Apolygus lucorum was studied and the significant mating inhibition phenomenon was observed in the newly mated insects.On this basis,we systematically studied the phenomenon and mechanism of the mating inhibition of the newly mated A.lucorum.The main results obtained are as follows:1.Through systematic mating behavior experiments,the mating characteristics,mating peaks and mating rhythm were clarified in detail.The mating process of A.lucorum can be divided into four steps: female calling,male approaching,male contacting and mating.The mating process is short,lasting for only 72.68 � 1.72 seconds.The results showed that A.lucorum begins to copulate from 3 days after emergence.The 7-day-old bug has reached the mating peak.The mating process mainly occurs in the photoperiod,the mating peak is at the first hour,and there are few mating occurs in the dark period.2.We confirmed the second mating of female in A.lucorum was inhibited within the 72 hours after mating,and the mating refractory period is at least 36 hours.Behavioral experiments showed that the extracts of accessory glands of unmated male and the spermathecae of mated female could significantly inhibit the mating rate of A.lucorum.In addition,the results showed that the myristyl acetate(MA),an antiaphrodisiac pheromone of other mirid bugs,had no effect on the mating behavior of A.lucorum.Hexyl butyrate(HB),which is known as the anti-pheromone could significantly reduce the mating rate.Through GC-MS comparative analysis of the extracts from the abdomen of virgin females and males and the spermathecae,we preliminarily found that MA was not identified in A.lucorum and the content of HB was very low in the spermathecae,so neither of the two compounds was the antiaphrodisiac pheromone of the A.lucorum.Acetic acid icosyl ester,which presented in unmated males and spermathecae,but not in virgin females,is predicted to be the antiaphrodisiac pheromone in A.lucorum.3.When using traditional chemical ecology methods to identify the antiaphrodisiac pheromone,we also studied the in vitro functions of several odorant receptors highly expressed in the male antenna of A.lucorum,according to the reverse chemical ecology method.The full-length cDNA sequences of 9 odorant receptors were cloned from the antennae of adult males and females.The qPCR results showed that all the 9 odorant receptors highly expressed in male and female antennae,and the expression levels of 2 odorant receptors in male antennae were significantly higher than that in female antennae.The in vitro functions of these 9 odorant receptors were studied by using Xenopus oocytes expression combined with the two-electrode voltage clamp technique.The responses the 9 odorant receptors to 61 odor compounds including sex pheromones,host plant volatiles and MA were tested.The results showed that AlucOR47 responded to linalool and its structural analogues.AlucOR57 responded to several plant volatiles.The remaining 7 odorant receptors could not be activated by any tested compounds.