Preliminary Studies On Morphology And Reproductive Biology Of Sexuals Of The Semiaphis Heraclei On Honeysuckle

Honeysuckle is one of the important bulk common Chinese herbs in China with Lonicera japonica Thunb.as its plant origin.With the increasing of honeysuckle cultivation area,its pests and diseases are becoming more and more serious.The aphid,Semiaphis heraclei(Takahashi),is the dominant pest in honeysuckle production areas and the most important biological factor affecting the yield and quality of honeysuckle.In spring,this aphid feeds on the honeysuckle shoots and tips,resulting in leaf deformation,abnormal flower development.The damaged leaves often roll up to protect the aphid from chemical pesticide,which make the aphid extremely difficult to control.Besides,the aphid reproduces with high rates.If aphid control is not thorough,a small number of individuals can cause the population to rebound rapidly.So The aphid has become a bottleneck problem limiting the green development of the honeysuckle industry.There is an urgent need to find new means of prevention and control.The S.heraclei reproduces solitarily for most of its life history,with only one generation of male and female sexual aphids mating before overwintering to lay eggs.The population size of the sexual aphid generation determines the number of overwintering eggs and the intensity of the aphid outbreak in the following spring,so the sexual aphid is a key stage in the life history of the S.heraclei,and studying the reproductive biology of the sexual aphid,especially the chemical communication mechanisms between the two sexes,can provide a basis for research on control tools.In this paper,we studied the morphological and behavioral characteristics and reproductive biology of male and female S.heraclei by combining morphological and behavioral methods,field observations and laboratory experiments.Furthermore,we used scanning electron microscopy to clarify the ultrastructure of the possible sex pheromone releasing and reception organs(scent plaques and antennal sensilla),and lay the foundation for resolving their mate recognition mechanism.The main results are as follows:1.Among the two wingless morphs(sexual female and apterae),the shape of the abdomen is the main feature for distinguishing sexual female from apterae.The abdomen of the female aphid is fusiform.Secondly,it can be distinguished by body width,head width,antennae length,mouthparts length,fore tibia length,middle tibia length,hind tibia length,cornicle length and cauda length.All indexes of apterae are greater than those of sexual female.2.Among three winged morphs(male,alatae and gynopara),they were distinguished mainly by the presence of external genitalia and abdominal color.The male has yellowish brown abdomen and external genitalia can be seen on the abdomen.Alatae has yellowish to yellowish green abdomen and no external genitalia was observed on the ventral surface.The gynopara has a green abdomen and no external genitalia was observed on the abdomen.Besides,body width,antennal length,fore tibia length,middle tibia length,forewing length and metathorax area were different among three winged morphs.The antennae of male was the longest,the other indexes were the shortest among three morphs.3.The male of S.heraclei actively searched the sexual female during mating process,which can be divided into six stages:searching,positioning,probing,pairing,insertion of sperm transfer and separation.The male may get off during probing and pairing stage.The male has no special courtship behavior(eg,dancing,chirping)during courtship,but the male’s antenna swing at high frequencies during the search process.Sexual aphids have a distinct rhythm of mating,only during the light period,but not during the dark period,and the daily mating peak was at 10:00-14:00.The sexual female has distinctive characteristics for the selection of egg laying sites,the main factors being the availability of nutrient sources and sites sufficiently secluded,with branches with bud scales being preferred,followed by bud scales and finally bark crevices.This result provides an important basis for finding the best time and site for S.heraclei control.4.The antennae of male and sexual female of S.heraclei had sex dimorphism.The antennae length of male aphid was about 1.90 times as that of female aphid.The difference of antennae between males and females was mainly manifested in the flagellum.There are 3 types sensilla and 3 types rhinaria,including trichoid sensillum subtype Ⅰ,trichoid sensillum subtype Ⅱ,campaniform sensillum,primary rhinaria subtype Ⅰ,primary rhinaria subtype Ⅱ and secondary rhinaria.The number of sensillum trichoid subtype Ⅰ in male aphid was significantly higher than that in female aphid.The secondary rhinaria only distributed on the antennae of male.The hind tibia of male is slender,while the hind tibia of sexual female is short and thick,and a large number of gonad patches are distributed.In this study,the identification characteristics of male and sexual female and reproductive biological characteristics of sexual aphid in S.heraclei were investingeted,which provided a theoretical basis for the prevention and control of it.At the same time,the secondary rhinaria on the antennae of male and the gonadal plaques of the hind tibia of sexual female were observed,which laid a foundation for the mate recognition mechanism of S.heraclei and the exploitation and utilization of sex pheromones.