Conspecific and heterospecific pheromones stimulate dispersal of entomopathogenic nematodes during quiescence

Ascaroside pheromones stimulate dispersal, a key nematode behavior to find a new food source. Ascarosides produced by entomopathogenic nematodes (EPNs) drive infective juvenile (IJ) emergence from consumed cadavers and dispersal in soil. Without ascarosides from host cadavers, Steinernema feltiae (EPN) reduce dispersal substantially. To determine whether other Steinernema spp. exhibit the same behavior, we compared S. feltiae and S. carpocapsae IJs without host cadaver pheromones. Unlike S. feltiae, S. carpocapsae IJs continued to disperse. However, S. carpocapsae IJs exhibited a temperature-dependent quiescent period. The IJ quiescent period increased at ≤20 °C but did not appear at ≥25 °C. Consistent with this, S. carpocapsae IJ quiescence increased from 30 min to 24 h at ≤20 °C over 60 days. The quiescent period was overcome by dispersal pheromone extracts of their own, other Steinernema spp. and Heterorhabditis spp. Furthermore, S. carpocapsae IJ ambush foraging associated behaviors (tail standing, waving, and jumping) were unaffected by the absence or presence of host cadaver pheromones. For S. feltiae, IJ dispersal declined at all temperatures tested. Understanding the interaction between foraging strategies and pheromone signals will help uncover molecular mechanisms of host seeking, pathogenicity and practical applications to improve the EPN’s efficacy as biocontrol agents.AFRI (2018-67013-28064)Space Florida Israel Innovation Partnerships (018-057)USDA-ARS (58-6042-6-001)USDA-NIFA Agriculture and Food Research InitiativeU.S. Department of AgricultureNational Institute of Food and AgricultureSmall Business Innovation Research (2017-33610-26808

The impact of caregiver mental health on child prosocial behavior: A longitudinal analysis of children and caregivers in KwaZulu-Natal, South Africa.

BackgroundProsocial behavior has positive social, cognitive, and physical health effects on the individual exhibiting the behavior as well as on society as a whole, and is integral to overall mental and physical wellbeing. The development of prosocial behavior is rooted in early childhood and learned through observation. As such, those spending time with children, especially their caregiver, play a critical role in their prosocial development. The current study investigates the impact of caregiver mental health on the prosocial development of young children over time.MethodsThis paper presents a secondary analysis of child prosocial development in the Asenze Study, a longitudinal, population-based cohort study based in KwaZulu-Natal, South Africa. Children were followed-up over time from an average age of five to seven years along with their caregivers. Linear GEE regression analysis was used to assess whether a change in presence of a mental health disorder in a caregiver during this 2-year interval (using the Client Diagnostic Questionnaire) impacted the development of their child's prosocial behavior (using the Strengths and Difficulties Questionnaire).ResultsAfter adjusting for early child-care, child HIV status, SDQ child prosocial subscale, SDQ total difficulties score, and household order score (CHAOS), children whose caregivers acquired a mental health disorder had a significantly smaller increase in prosocial behavioral development compared to children whose caregivers never had a mental health disorder.ConclusionsIdentifying contextually relevant modifiable factors such as this will help stimulate the development of interventions to promote prosocial development in childhood