| With the adjustment of crops planting structure,the transformation of land use,crops and crop composition change the food sources and ecological environment of pests,which often have obvious influence on the pest population in the field.The winter wheat-summer maize rotation is one of the main farming pattern in northern China.In recent years,the adjustment of crops planting structure is also aggregating the occurrence of Proxenus lepigone(Moschler),Ostrinia furnacalis(Guenée)and Conogethes punctiferalis(Guenée).However,the ecological mechanism of regulation on these pests at large scale is still unclear.In this paper,the effects of different farmland landscape composition and diversity on three species of pests in northern China.P.lepigone,O.furnacalis and C.punctiferalis population in winter wheat-summer maize rotation farmland system were studied.It shall provide a reference for analyzing the succession law and disaster mechanism of pests within the planting structure adjustment.In total,39 fields with winter wheat-summer corn rotation pattern were selected in northern China in 2018 and 2019 as the central plots of the experimental sites.Sexual attractants were used to trap the three adult insects,and the population was counted.The landscape variables at four scales of 0.5 km,1.0 km,1.5 km and 2.0 km were counted in the field survey,and the landscape variables were subjected to principal component dimensionality reduction treatment.The first three principal components were retained(PC1,PC2,and PC3),then the principal component and the landscape diversity index(Simpson D)were fitted to the values of the peak occurrence of the three adult pests by a linear mixed model.Finally,the effect of farmland landscape pattern on three pest populations in northern China was systematically evaluated according to the optimal model obtained from the Adjusted Akaike’s Information Criterion(AICc).The main findings are as follows:1.In 2018-2019,the overwintering adult of P.lepigone reached its peak period from mid-April to the end of April,the first generation adults at the end of June,the second generation adults at the end of July,and the third generation adults from the end of August and early September.Through the fitting of the same landscape variables,it was found that the response of the overwintering generation to the landscape pattern was not obvious The increase of landscape diversity at 2.0 km scale favored the occurrence of the first generation of adult insects in the wheat field,while the increase of the previous wheat area at 0.5 km scale boosted the occurrence of the second generation adult in the corn field.The occurrence amount of three generations of adults in maize field was positively correlated with landscape diversity at 1.0 km scale.2.In 2018-2019,the first generation of O.furnacalis in maize field reached its peak at early July and the second generation from late August to early September.It was found that wheat area ratio at 0.5 km scale were positively correlated with the population number of the first generation O.furnacalis adults.The planting area of corn and other crops at 1.5 km scale was positively correlated with the population of adult borer of second generation O.furnacalis.3.In 2019,the second generation of C.punctiferalis in the corn field peaked at late August.It was found that the population of the second generation C.punctiferalis adults in the corn field was positively correlated with the landscape diversity at 0.5 km scale and under the 1.0 km landscape scale were positively correlated with the proportion of woodlots in farmland landscape area. |
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