Influence Of Winter Crops On Arthropod Community In Winter And Early Rice Fields

Improving habitat management is an effective way of biological control. To explore the impact of arthropod community structure and dynamic as well as the effect of biological control in different winter crops in winter and the coming year, we designed an experimental model system of a microlandscape that included four treatments, three main local crops( Astragalus sinicus L., Brassica campestris L., Allium sativum L.) rotations with rice and fallow fields as controls, in order to provide theoretical basis for winter habitat management and biological control, and provide theoretical reference for agricultural landscape design and the selection of winter crop varieties.Based on the systematic investigation, the survey uncovered 101 species from 48 families and 9 orders, and the total individual number was 22999. The arthropod community of whole rice habitats mainly included arthropod natural enemies and non-pests, which species, number and richness level were the highest in Astragalus sinicus L. and Brassica campestris L. fields.As the weather cools, the climate deteriorated, the species and number of arthropod community in fallow fields and Allium sativum L. field sustained reduction in the winter, at the end of January to reach a minimum value. However Astragalus sinicus L. and Brassica campestris L. fields provided better habitat or refuge to arthropod, the specie richness and diversity index of arthropod community did not reduce in the period of cool and worst climate, ensured the abundance of overwintering arthropod community. The number and abundance of nun-pests in planting winter crop fields than in fallow fields before and after plowing. The results showed that planting winter crops(mainly Astragalus sinicus L. and Brassica campestris L.) had better protective effect of natural enemy community and nun-pests community in winter and early rice field.The species, specie richness and diversity index of pests were the highest in fallow fields, and the species, diversity index and community stability of natural enemies were the highest in Astragalus sinicus L. and Brassica campestris L. fields before plowing. After plowing, the species and specie richness of pests in Astragalus sinicus L. field was higher than in fallow fields, Allium sativum L. field was the lowest. The diversity index and evenness index of pests was the highest in fallow fields and was the lowest in Astragalus sinicus L. field, the species, specie richness, diversity index and evenness index of natural enemies were higher in Astragalus sinicus L. and Brassica campestris L. fields and was the lowest in Allium sativum L. field. The results showed that planting Astragalus sinicus L. and Brassica campestris L. could increase richness level of natural enemies in winter and the early rice field, and there was not growing trend of pest community.The one hundred worm strain rate of two target pests, Chilo suppressalis Walker and Cnaphalocrocis medinalis Guenee was the highest in fallow fields, the lowest number of Chilo suppressalis Walker in Brassica campestris L. field and the lowest number of Cnaphalocrocis medinalis Guenee in Astragalus sinicus L. field after plowing. At the peak of Chilo suppressalis Walker and Cnaphalocrocis medinalis Guenee damage, the one hundred worm strain rate of two target pests were the highest and damage was the most serious in fallow fields. In entire paddy habitats, natural enemy increased with increasing pest, and decreased with decreasing pest. In general, the characteristic parameters ratio of arthropod community was the highest in Astragalus sinicus L. field, followed by Brassica campestris L. field, and fallow fields were the lowest before and after plowing. The results showed that natural enemies had better biological control effect in paddy habitats. Planting winter crops, Astragalus sinicus L. and Brassica campestris L. could increase structural stability of ecosystem and biological control effect of pests, but planting Allium sativum L. had not distinct advantage than fallow fields. On the whole, Astragalus sinicus L. as a winter cover crop is better choice, followed by Brassica campestris L..