| Lymantria dispar(Linnaeus)belongs to the family Lepidoptera(Erebidae)and Lymantriinae(Lymantriinae).It is a worldwide forestry pest with a wide range of distribution,eating habits,heavy damage,and larvae.Features such as wind migration.Based on geographical distribution and whether the female moth is capable of flying,the gypsy moth is classified into L.dispar dispar,L.dispar japonica and L.dispar asiatica.Compared to European and American type gypsy moths,Asian females have the ability to fly and have a wider host range and have greater potential hazards.In order to rationally use the sex pheromone for population monitoring and behavioral regulation in the region where L.dispar asiatica occur in the future,their adult emergence,calling,mating and oviposition behaviors were observed under natural photoperiod,temperature and humidity conditions.The occurrence pattern of L.dispar asiatica in different types(tree species)of forest stands and the effect of different meteorological factors on trap catches,sticky wing traps baited with the synthetic sex pheromone(+)-disparlure were tested in five types of forest stands in Harbin City,P.R.China.Traps baited with three different solvent extracts of the female pheromone glands were also tested in a birch stand;Results revealed that:(1)The gypsy moth emergence peaks occurred 11 days(for females)and 12 days(for males)after their pupations.Both sexes of adults emerged from 2:00 am(2 hrs before the onset of photophase)to 9:00 pm(3 hrs into the scotophase),with an emergence peak occurring at 9:00 am for males and one at 11:00 am for females,respectively.The female adults started to call about 2 hrs after their emergence.The "calling rate"(%of calling females)for the newly emerged females(1-day-old)increased gradually with time,and reached 75%during the 1st photophase hr,and near 100%after that for the older females(2-day-old or older).Adults started mating on the same day after their emergence,with a major peak occurring during daytime at 2:00 pm(11 hrs into the photophase)and a second(minor)peak appearing during night at 0:00 am(6 hrs into the scotophase).The major ovipositon peak occurred during the photophase at 6:00 am,and the second(minor)ovipositon peak appeared during the scotophase at 8:00 pm.In summary,L.dispar asiatica adults displayed obvious circadian rhythms in their emergence behaviors.(2)Traps baited with the female gland extracts with n-hexane,methylene chloride and diethyl ether in the birch stand captured a total of 58,50,and 16 males,respectively.The n-hexane-based extract was the most attractive(46.8%of the overall trap catches)and its trap catch was significantly higher than that of diethyl ether extract(P<0.05),but was not different from that of methylene chloride extract(P>0.05).The electroantennogram(EAG)responses from male antennae to n-hexane extract were significantly higher than to the other two extracts(P<0.05).The sex pheromone content/production was the highest in the 2-day-old females,and then decreased with aging.In conclusion,hexane is the best solvent for extracting the female sex pheromone glands of the Asian gypsy moth among the three solvents tested,L dispar asiatica adults displayed obvious circadian rhythms in their reproductive behaviors.(3)Traps baited with(+)-disparlure in the elm(Ulmus pumila),birch(Betula platyphylla),Mongolian oak(Quercus mongolica),Mongolian Scotch pine(Pinus sylvestris var.Mongilica Litv.),and Dahurian larch(Larix gmelinii)stands captured a total of 34,30,29,9 and 15 L.dispar asiatica males,respectively.The numbers of male moths captured in the elm,birch,and Mongolian oak stands were significantly higher than those in the other two stands(P<0.05;n=3).The first trap catches of L.dispar asiatica males occurred in the elm stand,and trap catch peaks appeared earlier in the elm,birch and larch forest stands than in the pine and Mongolian oak forest stands.The trap catches stopped almost at the same time for all the five stands.Meteorological factors showed a significant effect on the number of L.disparasiatica males captured.At the wind speed level III(3.4-5.4 m/s)or higher,the trap catches were significantly lower than those at the wind speed levels I-II(0.3-3.3 m/s).Sunny/cloudy or raining(precipitations)days showed no significant effects on the trap catches.The daily maximum and minimum temperatures both affected the captures;based on a linear relationship between the temperatures and the average daily male moth captures,the trap catches increased with the rising daily minimum temperature within the range of 14 to 23 ?.The daily maximum temperatures at 26-30 ? range seemed to be optimal for the male flight activities,and furfher increase in the daily maximum temperature resulted in a decrease in the trap catches.In conclusion,the occurrences of the L.dispar asiatica are affected by the host plant species,wind speeds and temperatures in the forests. |
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