Dimensionamento de amostra na estimação da população de corós em áreas de campo nativo e de cultivo no Estado do Rio Grande do Sul

Distribution of Bemisia tabaci within soybean plants and on individual leaflets

“…According to the Morisita index, most of the leaflets from the middle third of the soybean plants (55%) displayed an aggregate distribution of the whitefly nymphs of the four instars (Table S3); they mainly concentrated in the middle and bottom areas of the leaflets (Figure , Figure S2B). In all samples from this third that presented a Morisita index significantly higher than 1, the variance was higher than the mean and the negative binomial parameter k tended toward zero (k≤6.23) (Table S3), also indicating an aggregate distribution of B. tabaci nymphs for most of the soybean leaflets evaluated (Cargnelutti Filho et al, ).…”

“…On the other hand, the arrangement of the nymphs on the leaflet surface showed a similar pattern of aggregation in 85% of the leaflets evaluated, according to the Morisita index (Table S1), with the nymphs clearly concentrating in the middle and bottom regions of the area (Figure , Figure S1). In all samples that presented a Morisita index significantly higher than 1, the variance was higher than the mean and the negative binomial parameter k tended toward zero (k≤2.9) (Table S1), also indicating an aggregate distribution of B. tabaci nymphs in 85% of the soybean leaflets evaluated (Cargnelutti Filho et al, ). Therefore, B. tabaci nymphs feeding on soybean plants under greenhouse conditions concentrate in the middle and bottom parts of the leaflets.…”

“…On the other hand, in the upper and lower thirds of the soybean plants from the field, the distribution of B. tabaci nymphs in the leaflets was predominantly random, with 61.5% (upper third; Table S2) and 70.8% (lower third; Table S4) of the samples presenting a random arrangement according to the Morisita index. In all samples from these thirds that showed a Morisita index close to 1, the variance was lower or very close to the mean and the negative binomial parameter k did not tend toward zero (Tables S2 and S4), indicating a random distribution of B. tabaci nymphs for most of the soybean leaflets evaluated (Cargnelutti Filho et al, ). Therefore, there is no defined pattern of distribution for B. tabaci nymphs feeding on leaflets from the upper and lower thirds of soybean plants grown under field conditions.…”

“…The Morisita index is used to quantify the degree of dispersion of the individuals inside a certain population, classifying its pattern of spatial arrangement as: random, if I δ = 1; aggregate, if I δ >1; and uniform or regular, if I δ <1 (Cargnelutti Filho et al, ; Moradi‐Vajargah et al, ; Stürmer et al, ).…”

“…The negative binomial parameter k is an aggregation parameter, often used to assess distribution patterns in insect populations (Cargnelutti Filho et al, ; Moradi‐Vajargah et al, ; Stürmer et al, ). Decreasing values of k (tending toward zero) are associated with increased aggregation of the insects within the sample units, whereas increases in k indicate an increasingly random population distribution (Waters, ; Young & Young, ).…”