Survey of Heterodera glycines Population Densities and Virulence Phenotypes During 2015-2016 in Missouri.

The soybean cyst nematode (SCN), Heterodera glycines, is one of the most important pathogens of soybean. Periodic monitoring of SCN population densities and virulence phenotypes is necessary for developing management strategies utilizing resistant cultivars, the primary strategy used to combat this pest. Therefore, we conducted a statewide survey of Missouri to determine SCN population densities and virulence phenotypes during 2015-2016 and compared these results with a similar survey conducted in 2005. SCN population densities were determined for 393 soil samples representing 74 soybean-producing counties across eight geographical regions of Missouri. Eighty-eight percent of samples tested positive for SCN, up from 50% in 2005, and population densities ranged from 125 to 99,000 eggs per 250 cm3 of soil. The virulence phenotypes of 48 SCN populations also were determined. For this, female indices (FI) were calculated by dividing the mean number of females that develop on the roots of a set of resistant soybean indicator lines by the mean number of females that develop on the roots of susceptible cultivar Lee74 after 30 days in the greenhouse then multiplying by 100 to obtain a percentage. Notably, all SCN populations evaluated during 2015-2016 had a FI > 10 on PI 88788, the most widely used source of resistance in Missouri, in contrast to 78% in 2005. Moreover, 50% of these populations had a FI > 50 on PI 88788, up from 16% in 2005. Forty-three percent of populations tested also had a FI > 10 on Peking, the second most common source of resistance by farmers. Our results show that over the last decade, SCN has become more prevalent in Missouri fields. Additionally, the percentage of individuals within SCN field populations that are virulent on PI 88788 and Peking has markedly increased. The results stress the importance of rotating cultivars with different types of resistance when using resistant cultivars to manage SCN.

Developmental Trajectories of Child Sexual Behaviors on the Path of Sexual Behavioral Problems: Evidence From a Prospective Longitudinal Study.

There is little information about the onset and the developmental course of child sexual behavior problems (SBPs), including sexually intrusive behaviors (SIBs). Using data from the Vancouver Longitudinal Study on the Psychosocial Development of Children, the current study examined the presence of distinct patterns of sexual development among children. A normative sample of preschoolers ( N = 354) with a small clinical subsample were followed from age 3 to 8 with repetitive measurements of sexual behaviors using a revised version of Child Sexual Behavior Inventory. Semiparametric group-based modeling identified four distinct sexual development trajectories: the very low (10.5%), the low declining (27.8%), the moderate stable (48.3%), and the high-rate increasing (13.4%). In contrast to the other developmental trajectories found, the high-rate-increasing pattern showed that sexual behaviors became increasingly extensive after school entry. Children characterized by this developmental pattern, especially boys, were more likely to be involved in SIBs after elementary school entry than those in the other groups. Findings highlight the presence of multiple developmental trajectories of sexual development with significantly different behavioral patterns after school entry.

Child and Adolescent Disposition Model: An Examination of the Temperament Factor Structure Within Early Childhood.

Lahey and Waldman proposed a temperament theory of conduct disorder (CD). Critical is the hypothesized temperament structure in which three relatively uncorrelated temperament dimensions (i.e., negative emotionality, daring, prosociality) central to CD are theorized to emerge in early childhood. The validity of this hypothesized factor structure in early childhood is unknown. The current study seeks to fill this gap by examining Lahey and Waldman's hypothesized temperament structure utilizing a Canadian sample ( n = 283) of preschoolers. Confirmatory factor analyses (CFAs) were performed to compare the hypothesized relatively uncorrelated temperament structure with two alternative models (i.e., correlated three-factor and single-factor structure). The CFA indicated that the temperament dimensions are present in early childhood and are relatively uncorrelated consistent with previous work at later developmental stages. Of importance, the findings highlighted key gender differences observable at 3 and 4 years of age. The theoretical implications are discussed.