Reproductive Behavior And The Host Selection Mechanism Of Micromelalopha Sieversi

Micromelalopha sieversi (Staudinger) is an important pest in Poplar plantations whichwidely distributed in the middle-east of China. The huge economic losses and severeenvironmental damage were caused by the outbreakes of the pest. In order to understand itsbiology, develop the attractants and select the resistent Poplar clones for the ecologicalmanagement, its reproductive and ovipositon host selection behavior were observed, sexpheromone component and host volatiles were analynized with GC, GC-MS, and GC-EADmethods. The results are as follows:(1) M. sieversi adult emergence showed two "hump" characteristics, one peak was at4:00andthe another one at17:00. The frist emergence peaks of male adult occurred1h earlier and thesecond peak was1h later than female adult, which was different from the previously reported"unimodal" rhythm. Under the same temperature, humidity, and photoperiod conditionds, theemergence period of M. sieversi became shorter graduadly from1stto4thgeneration.Temperature was the major environment impact factor affecting the adult emergence, humidityalso influenced on the adult emergence, however, the change of photoperiod did not affect theadult emergence rate.(2) The phenomenon that of M. Sieversi had the calling and mating behavior on the dayof emergence indicated that it was close to or sexual maturity at the frist day after emergence.They could copulate in two ways, the most common way of female moth was showed thatcalling behavior via pheromone gland protruding; male moth showed active flying, crawling,and wings fanning behavior and then copulated. In some cases, the1-d-old female moth couldalso complete the mating process through a brief flying and crawling without the releasing ofsex pheromone. The female moth had a clear circadian rhythm of calling behavior which hadtwo peaks at4:00and21:00, respectivly, and the calling behavior did not occur during the photophase. Although the mating rate and calling rate showed no significant difference among1-to5-day old adult, the calling and mating period became shorter with the increasing adultage.(3) Male did not abort mating immediately after ejaculation which completed within45min indicating that there was the protective behavior after copulation. The female moths wereoccupied by male with mating posture after ejaculation. The mating and ejaculation times werenegatively correlated with adult age, but there were no significant differences in ejaculatoryamount among different ages. The duration of mating was shortened as number of the femaleor the number of couples increased, however it was lengthened by increased number of malemoths. The mating rate was reduced and the duration of mating was shortened as theconcentration of sex pheromone increased.(4) The sex pheromone of M. sieversi was extracted by means of solvent extraction,dynamic headspace collection, and SPME. The solvent extraction of pheromone gland hadshowen the EAG activity and trapping efficacy in the wild. M:OAc was the pheromonecandidate of M. sieversi via the analysis of the GC-EAD and GC-MS. Female sex pheromonerelease showed a significant circadian rhythm which was consistant with calling behavior, therelease reached maximum at19:00-20:00, then declined, further showed a second release peakat4:00, and then continued to decline. Their release also declined when the moth ageincreased.(5) There was the response threshold of1-d-old male moths to the crudefemalepheromone gland extracts. This threshold was not only related to the concentration level, butalso to the time range levels. The maximum reaction threshold could be reached by10FE and0.1FE can not evoke any EAG response. One-d-old male had the significant differences inEAG response to the same sex pheromones extracts at different times of a day, and theresponse sensitivity were strongest at19:00and21:00. The EAG response of male moth wasdeclined significantly to the sex pheromones extracts extractd from female moth that older than3d. (6) Female moths had the preference which was not showen on the male among differentPoplar clones. The clones of Biyu and108had the most attraction for the female moths whencompared to other treatments. The mated female moths without oviposition were moreselective to the host than virgin moths. There were more egg masses and the total number ofeggs but less eggs in each egg mass on the preference host.(7) There were19kinds of chemicals identified from5clones of Poplar leaf volatileswhich was mainly composed of alkanes, alkenes, alcohols, esters and aldehydes. The contentsof salicylaldehyde, cis-3-hexenol, cis-3-Hexen-1-acetate,1-hexen-3-ol were relatively high inhost. N-Hexadecane and Caryophyllene were relatively high in the preference host in whichDibutyl phthalate could not be detected.