Study On Host Choice And Niche Of Monochamus Alternatus Larvae

Monochamus alternatus Hope is the important trunk borer of trees, and it’s also thesignificant media of Bursaphelenchus xylophilus. Through the study of food choices and feeding area on different growth conditions in pine branches of Monochamus alternatus Hopeadults, and the study of alternatus’ distribution regularity on black pine, and the study of thespatial niche of Monochamus’ mature larvae, the occurrence regularity of Monochamusalternatus Hope appeared on coastal pine forest were systematic discussed in this paper byecological method.1. The study of the Monochamus adults’ host selection behavior during feeding preferenceFeeding the Monochamus adults adults indoor. Adult feeding on different age alone resultshowed: M. alternatus adult feed at one year branch is the most, life span is the longest. Maleand female adults mean feeding area38.96cm2and35.26cm2in thirty days. Mean life span aretwenty seven days and twenty five days in part. Adult can feed two years old branch directly.Feeding quantity and life span are more than one year old branch. Feeding area of male andfemale adults are15.61cm2and16.11cm2in part. Mean life span are ninth days and twentydays in part. Adult feed three years old branch a little. Life span is twele days. Adult can’t feedfour years old branch directly, but life span is more than control group.Beetle adult has feeding preference at different old branchs in field. Stay time is longer atone to three years old branchs than four years old branchs. Supplement nutrient at one to threeyears old branchs is more. Beetle feeding quantity is more and more from the first emergenceday to the twentieth day, and it’s the most at the twentieth day, about3.86cm2.head-1.d-1, thengradually reduce. The difference value of feeding quantity between ephemeral and biennial isbig, P<0.05, but the difference value between biennial, triennial and the four annual plants is small,P>0.05. A little beetle can feed at oviposition branch at the twentieth day from its emergence,about0.26cm2.head-1, accounting for2.1%of total feeding area only. What’s more, feeding atbranchs on the south is more than other direction, accounting for30.5%of total feeding area.2. Distribution regularities of M. alternatus oviposition scarsWe found M. alternatus can lay eggs in whole trunk. Oviposition site on different plantsare random. as a whole, oviposition scars density is equal on trunk the upper, middle and lowersegment, Only in the middle density slightly largern. There is certain relationship betweenoviposition scars and trunk diameter or tree height. Between oviposition site(y)and trunkdiameter(x)is:y=0.1727x4-8.1411x3+128.13x2-761.34x+1481.7R2=0.907; Between oviposition site (y)and tree height(x) is y=136.67x4-1676.7x3+6983.3x2-11243x+5800R2=1.000. M.alternatus had the highest oviposition preference to trunk diameter of Pinus thunbergii in9~15cm and tree height in4~7m. While trunk diameter in9~13cm, the beetles depositedsignificantly more eggs. In this range, hosts are the most affected by M. alternatus. There areno oviposition scars when diameter of host greater than17cm or tree height greater than7m.there are more oviposition scars in the trunk1~2m, only a little scars in more than3m. At thesame time, the beetles lay eggs in well-lit place, south of the trunk have the most ovipositionscars.3. Distribution of niche of M. alternatus‘s and A. rusticus ‘s mature larvaeThe research results on niches of their mature larvae indicated that the niche breadth of M.alternatus was0.841in April，Larvae distribut in the whole plant, but A. rusticus distribut inthe trunk below3m, the niche breadth was0.640, it’s different in the two bettles, niche overlapwas0.842, coefficient of competition was0.675. The niche breadth of M. alternatus is0.841inJuly, distribution in the trunk below3m in main, the niche breadth of A. rusticus0.470, nicheoverlap was0.880, coefficient of competition was1.50. The two bettle were all in the trunk below2m. the niche breadth were0.500and0.420, resrespective, niche overlap and coefficient ofcompetition is enlargement. Larvae distribut in the whole weak plant, the niche breadth is widerthan A. rusticus. the niche breadth of the two beetles were0.904and0.360, resrespective. M.alternatus distribut in the dead trunk below3m, it’s similar to A. rusticus, the niche breadth ofthe two beetles were0.53and0.46.