Demographic Variation And The Relationship Between The Species And Environment Of Coccinellids In Central Hebei Province

Coccinellids is treated as the main predator in the north china.The research starts in the farming area Gu An,central He Bei province,from March,2003 to November, 2008.Studying in the format of"season-habitat-pest-natural enemy"which do effects on Coccinellidae species temporal variation and the habitat selection,it can be summarized as followed:1.The dominant species of coccinellids in agricultural areas in central Hebei province is Propylea japonica and Leis axyridis,the dominant species of coccinellids in different habitats has changed with the season changing,L.axyridis and Coccinella septempunctata were dominant spiecies which roosted in forest belt before the crop planted,P.japonica as the dominant species in the middle and last period of crop planted which roosted in crop belt;2.During the crop growing,Coccinellids turn on different habitat selection.In May, P.japonica and L.axyridis show more efficacious in coppice shoot forest belt(P. japonica P=0.01,α=0.05;L.axyridis P=0.034,α=0.05).In last June and July,the two Coccinellids show more efficacious in Corn-poplar intercrop(P.japonica P=0.047,α=0.05;L.axyridis P=0.03,α=0.05),at the same time,Coccinellids in coppice shoot forest belt very sparse,this phenomenon shows the species of coccinellids move in various patch obviously;3.In different time,coccinellids will have different spatial distribution pattern, during the crop growing,it will appear aggregated distribution in the form of density dependence(lg(v)=0.0256+1.431lg(m)(R=0.9525),lg(v)=0.0246+1.095lg(m) (R=0.9956),lga＞0,b＞1),at other time,it appeared andom distribution and uniform distribution;4.Aphids are the main pests in central Hebei Province.In wheat fields,L.axyridis show the following effect obviously(Sig=0.012,P=0.988),in the early period of the soybean field planted,P.japonica and L.axyridis show the aphids-oriented effect obviously(L.axyridis Sig=0.008,P=0.671;P.japonica Sig=0.06,P=0.474),in the two kinds of cron field,P.japonica has show the aphids-oriented effect more obviously(Corn-poplar Intercrop Sig=0.093,P=0.813;Corn Sig=0.312,P=-0.376). The effect reduced with the lapse time,with the crop full-blown and the development of population;5.Meteorological factors has a certain affected to the density of Coccinellids,it also does its effect on species density of P.japonica in which temperature factor do less effect on it.The most obvious effect is from the duration of sunshine(r(y,1) =0.936＞temperature(0.865)＞precipitation(0.825));6.Different kinds of Coccinellids have difference according to when they are formed.For example,C.septempunctata,in this area,can be featured as discontinuity and low density.Both are limited to be a natural enemy.However,P.japoniaca,as the dominant species,with assistance of coherence and high density in quantities,is doing positive effort on crops;7.The forest belt makes more sense on species forming and rebuilding.It is called as"species pool"towards the farmland natural enemy.Meanwhile,the forest belt is also helpful on the crops' early growing period and on going through the cold winter. Therefore,combined with various forest belts,it can generate more nice conditions for Coccinellids living.