三种类型稻田节肢动物群落结构、亚群落内禀增长率与链节数的关系

The relationship among structures, intrinsic rate of increase of functional guilds, and link numbers of arthropod community in three types of rice field under organic rice production system

通过对 3类型稻田 (有机养鸭田、有机稻田和常规化防田 )田间节肢动物群落调查 ,比较了节肢动物总群落丰富度、丰盛度、周转量、3个亚群落 (天敌、中性昆虫、害虫 )调查期间的平均内禀增长力 (r)和通过构建以稻田蜘蛛为顶、中位物种的群落食物网的链节数与害虫、天敌亚群落的 r和链节增长率关系。结果表明 :整个调查期间 ,总群落丰富度呈上升趋势 ,移栽后 72 d前 ,3类稻田总群落丰盛度、丰富度依次为 :有机稻田 >有机养鸭稻田 >常规稻田 ;3类稻田节肢动物群落周转量时间动态均呈上口抛物线趋势 ,其最低值和出现时间依次为 :常规稻田 33.98、74 .1d;有机养鸭田 33.90、79.1d;有机稻田 33.4 9、5 4 .0 d,有机稻田和常规化防田群落周转量和害虫数量呈显著的负相关。 3类稻田中性昆虫亚群落在调查期间的 r依次为 :有机稻田 (0 .0 6 6 5 ) >常规化防田 (0 .0 6 5 2 ) >有机养鸭田 (0 .0 5 0 9) ;天敌 r依次为 :有机稻田 (0 .0 35 2 ) >有机养鸭田 (0 .0 2 4 3) >常规化防田(- 0 .0 132 ) ;害虫的 r依次为 :常规化防田 (0 .0 4 78) >有机养鸭田 (0 .0 199) >有机稻田 (0 .0 198)。 3类稻田总链节数依次为 :有机稻田 (6 6 2 3348) >有机养鸭田 (2 4 982 17) >常规化防田 (136 3372 ) ;

A major characteristic of organic rice production is without the use of any chemical pesticide and fertilizer. In this rice production system, ecological regulation is an important strategy in managing pest problems. To assess the potential of this strategy, it is necessary to understand the relationship among functional guilds (insect pests, neutral insects and natural enemies) of the rice arthropod community. This paper aimed to approach regularities among structures, intrinsic rate of increase of functional guilds, and link numbers of arthropod community in three types of rice field, namely: organic rice field (ORF), organic rice field with ducks release (ODR), and conventional chemical control rice field (CCF). The experiment was conducted in Qianjin farm of Chongming County, Shanghai City with three plots (1500m^2 per plot). At 15 days after transplanting, sampling of arthropods was done on the three rice fields by using a suction device. Sampling was repeated with five days interval. The arthropods were sorted into three functional guilds, that is, natural enemies, insect pests, and neutral insects. All arthropods belonging to the same guild were pooled in the data analyses. The following indices were used: community turnover, To (t) =((a+b)/(c+d-e)) ×100% and mean intrinsic rate of increase of functional guild, r=(2.3/t_2-t_1) × ( lg N_2- lg N_1) . The potential links of food web ( L )=individual numbers of top species×(individual numbers of intermediate + base species) + individual numbers of intermediate × base species, per sampling. The link numbers of each pest = L divided by the total pests and the link numbers per natural enemy = L divided by total natural enemy. Results showed that richness of arthropod community increased with time until 72 days after transplanting. The relationship between community turnovers and time was fitted by a parabola in three types of rice fields. The order of the lowest value of community turnover in each rice field was CCF 33.98,74.1d; ODR 33.90,79.1d; ORF 33.49,54.0d. Community turnovers of ORF and CCF were negatively related to population size of pest. While abundance and richness of arthropod community until 72 days after transplanting is ORF>ODR>CCF. The intrinsic rate of increase of neutral insects is higher in ORF (0.0665) than in CCF (0.0652 and ODR (0.0509). Likewise, natural enemies were greater in ORF (0.0352) than in ODR (0.0243) and CCF (-0.0132). Inversely, insect pests were greater in CCF (0.0478) than in ODR (0.0.0199) and ORF (0.0198). The order of total link numbers is ORF (6623348)>ODR (2498217)>CCF (1363372), and the mean link numbers per natural enemy is ORF (5627.3)>ODR (3652.4)>CCF (2279.9), indicating that ORF had a more robust ecosystem than CCF. There were linear correlations between the intrinsic rate of increase of insect pests and natural enemies, and the increase rate of link numbers. The slope between the intrinsic rate of increase of pests and the increase rate of link numbers for ORF or ODR was 214% and 233% greater than that of CCF. The slope between the intrinsic rate of increase of natural enemy and the increase rate of link numbers of ORF was 151% and 89.4% higher than that of ODR and CCF,respectively.