Discarded vehicle tires and their association with mosquito vector abundance across socioenvironmental gradients in New Orleans, LA.

Discarded vehicle tires serve as habitat for mosquito vectors. In New Orleans, Louisiana, discarded tires are an increasingly important public concern, especially considering that the city is home to many medically important mosquito species. Discarded tires are known to be associated with mosquito abundance, but how their presence interacts with other socioenvironmental gradients to influence mosquito ecology is poorly understood. Here, we ask whether discarded tire distribution could be explained by social factors, particularly median income, home vacancy and human population density, and whether these factors interact with urban heat islands (UHI) to drive mosquito vector assemblages. We surveyed tire piles across the city and adult mosquitoes in 12 sites, between May and October of 2020. We compared this data with the social indicators selected and UHI estimates. Our results show that median income and human population density were inversely related to tire abundance. Tire abundance was positively associated with Aedes albopictus abundance in places of low heat (LS) severity. Heat was the only predictor for the other monitored species, where high heat corresponded to higher abundance of Aedes aegypti, and LS to higher abundance of Culex quinquefasciatus. Our results suggest that low-income, sparsely populated neighborhoods of New Orleans may be hotspots for discarded vehicle tires, and are associated with higher abundances of at least one medically important mosquito (Ae. albopictus). These findings suggest potential locations for prioritizing source reduction efforts to control mosquito vectors and highlight discarded tires as a potential exposure pathway to unequal disease risk for low-income residents.

Do container size and predator presence affect Culex (Diptera: Culicidae) oviposition preferences?

ABSTRACT Organisms with complex life cycles typically do not exhibit parental care. Hence, the ability of adult females to choose quality oviposition sites is critical for offspring success. Gravid females of many insect taxa have the capability to detect environmental conditions in water-holding containers (e.g., resource level, presence of competitors or predators) and to choose the sites that are most suitable for offspring growth and development. Mosquitoes may also detect physical container characteristics related to water permanence such as surface area, volume, or container size, and some species such as those in the genus Culex have been shown to prefer larger containers. However, predators may also preferentially colonize larger containers; thus, ovipositing females may face decisions based on cues of site quality that balance the costs and benefits for offspring. We used a field experiment to evaluate the oviposition preferences of two Culex species in response to experimental container size and predator abundances within the containers. We found that both species avoided ovipositing in the largest containers, which have high abundances of Chaoborus sp. and dragonfly larvae (predators). However, the container size most commonly chosen for oviposition (15-L buckets) also had high mean abundance per liter of dragonfly larvae. These results suggest either prey naiveté or reduced vulnerability of these species to dragonflies compared to Chaoborus sp. Other potential mechanisms for the observed patterns are discussed.

Forest litter crickets prefer higher substrate moisture for oviposition: Evidence from field and lab experiments.

For insects, choosing a favorable oviposition site is a type of parental care, as far as it increases the fitness of its offspring. Niche theory predicts that crickets should show a bell-shaped oviposition response to substrate moisture. However, lab experiments with mole crickets showed a linear oviposition response to substrate moisture. Studies with the house cricket Acheta domesticus also showed a linear juvenile body growth response to water availability, thus adult ovipositing females should respond positively to substrate moisture. We used a field experiment to evaluate the relationship between oviposition preference and substrate moisture in forest litter-dwelling cricket species. We also evaluated oviposition responses to substrate moisture level in Ubiquepuella telytokous, the most abundant litter cricket species in our study area, using a laboratory study. We offered cotton substrate for oviposition which varied in substrate moisture level from zero (i.e., dry) to maximum water absorption capacity. We used two complementary metrics to evaluate oviposition preference: (i) presence or absence of eggs in each sampling unit as binary response variable, and (ii) number of eggs oviposited per sampling unit as count response variable. To test for non-linear responses, we adjusted generalized additive models (GAMM) with mixed effects. We found that both cricket oviposition probability and effort (i.e., number of eggs laid) increased linearly with substrate moisture in the field experiment, and for U. telytokous in the lab experiment. We discarded any non-linear responses. Our results demonstrate the importance of substrate moisture as an ecological niche dimension for litter crickets. This work bolsters knowledge of litter cricket life history association with moisture, and suggests that litter crickets may be particularly threatened by changes in climate that favor habitat drying.

What does not kill them makes them stronger: larval environment and infectious dose alter mosquito potential to transmit filarial worms.

For organisms with complex life cycles, larval environments can modify adult phenotypes. For mosquitoes and other vectors, when physiological impacts of stressors acting on larvae carry over into the adult stage they may interact with infectious dose of a vector-borne pathogen, producing a range of phenotypes for vector potential. Investigation of impacts of a common source of stress, larval crowding and intraspecific competition, on adult vector interactions with pathogens may increase our understanding of the dynamics of pathogen transmission by mosquito vectors. Using Aedes aegypti and the nematode parasite Brugia pahangi, we demonstrate dose dependency of fitness effects of B. pahangi infection on the mosquito, as well as interactions between competitive stress among larvae and infectious dose for resulting adults that affect the physiological and functional ability of mosquitoes to act as vectors. Contrary to results from studies on mosquito-arbovirus interactions, our results suggest that adults from crowded larvae may limit infection better than do adults from uncrowded controls, and that mosquitoes from high-quality larval environments are more physiologically and functionally capable vectors of B. pahangi. Our results provide another example of how the larval environment can have profound effects on vector potential of resulting adults.

Witnesses to hunger: participation through photovoice to ensure the right to food.

Currently 30.2% of female-headed households with children in the United States experience food insecurity, defined as the lack of access to enough food for an active and healthy life. In 2007, approximately 12.4 million children were at risk for hunger. When female-headed households and households with children have the highest prevalence of food insecurity and hunger in the US, the participation of low-income mothers in the development and administration of policies and programs related to nutrition and poverty are fundamental to the process of ending hunger and improving child well-being. In this article, we describe the Witnesses to Hunger program, a participatory advocacy project that uses the "photovoice" technique to engage mothers to take photos and record their stories about poverty and hunger with the intent to inform social welfare policy in the US. Witnesses to Hunger is grounded in the human rights framework that is supported by international conventions on the rights of women, the rights of the child, and economic, social, and cultural rights. The Witnesses to Hunger program works to increase civic participation of low-income women and to maintain a strategic public awareness campaign. After introducing the Witnesses to Hunger program, this article describes the past decade of unchanging food insecurity disparities, demonstrates the lack of participatory dialogue in health and welfare programs, and provides examples of how Witnesses to Hunger counters the conventional dialogue about welfare. Throughout, this paper demonstrates how the participatory approach of the Witnesses to Hunger program improves our understanding of basic human needs and the social determinants of health, and informs legislators on how to improve health and welfare policy.

The negative effects of poverty & food insecurity on child development.

This paper addresses the importance of the first three years of life to the developing child, examines the importance of early childhood nutrition and the detrimental effects on child health and development due to poverty and food insecurity. As development experts learn more about the importance of the first three years of life, there is growing recognition that investments in early education, maternal-child attachment and nurturance, and more creative nutrition initiatives are critical to help break the cycle of poverty. Even the slightest forms of food insecurity can affect a young child's development and learning potential. The result is the perpetuation of another generation in poverty. Conceptualizing the poorly developed child as an embodiment of injustice helps ground the two essential frameworks needed to address food insecurity and child development: the capability approach and the human rights framework. The capability approach illuminates the dynamics that exist between poverty and child development through depicting poverty as capability deprivation and hunger as failure in the system of entitlements. The human rights framework frames undernutrition and poor development of young children as intolerable for moral and legal reasons, and provides a structure through which governments and other agencies of the State and others can be held accountable for redressing such injustices. Merging the development approach with human rights can improve and shape the planning, approach, monitoring and evaluation of child development while establishing international accountability in order to enhance the potential of the world's youngest children.