Impacts of ground ultra-low volume adulticide applications on Culex pipiens and Culex restuans (Diptera: Culicidae) abundance, age structure, and West Nile virus infection in Cook County, Illinois

Since the introduction of West Nile virus (WNV) to the United States over 20 years ago, thousands of cases of human disease and death have been reported. Yearly seasonal outbreaks continue to persist, and the city and suburbs of Chicago, Illinois, is considered a "hot spot" for WNV activity. To interrupt WNV transmission, ground ultra-low volume (ULV) adulticide applications are regularly used to reduce Culex pipiens L. and Culex restuans Theobold (Diptera: Culicidae) abundance and infection. The real-world effectiveness of adulticide applications has not been comprehensively assessed, and prior studies, including our own investigation, have yielded inconclusive or conflicting results. Therefore, we expanded our prior work and evaluated the effects of 5 sequential weekly truck-mounted ULV adulticide applications in large residential areas in the northern suburbs of Chicago, Illinois, in 2019 and 2020. Each day, Cx. pipiens and Cx. restuans host-seeking and gravid mosquitoes were collected to assess abundance, age structure, and WNV infection rates. Adulticide applications resulted in significant reductions of both host-seeking and gravid abundance on the night of treatment. The reduction in host-seeking mosquitoes was followed by a reduction in gravid mosquitoes trapped 3 and 4 days after adulticide application and an increase in the proportion of nulliparous mosquitoes. WNV infection rates were significantly reduced in treatment sites as compared to untreated sites when infection rates were higher in 2020. This large-scale study provides comprehensive evidence that ground ULV adulticide applications are an effective tool in an integrated mosquito management program for combating WNV vectors and infection risk.

Depression moderates the association between pregnancy and suicidal ideation among pregnant and non-pregnant reproductive age women in Brazil

BACKGROUND

Maternal mental health problems are a serious public health concern. Previous data reported that pregnancy might have a protective effect against suicide. In contrast, more recent studies suggested that the prevalence of suicidal ideation (SI) is higher among pregnant women compared to the general population. Using a nationally representative population-based sample of Brazilian reproductive-aged women, this study aims to assess whether SI is more prevalent among pregnant women in comparison with nonpregnant woman.

METHODS

We used data from the Brazilian National Health Survey (PNS) of 2019, a cross-sectional study that comprised a representative sample of residents in private households in Brazil. For the analysis of this study, we selected women aged between 15 and 49 years old who have answered the questionnaire of the Selected Resident of the PNS, which comprised a sample of 27,249 women. Logistic regression models were performed to obtain crude and adjusted odds ratios (OR) and 95% confidence intervals (95%CI) for the association between pregnancy status and SI.

RESULTS

The prevalence of SI during pregnancy was 6.8% (95% CI: 6.2-7.4). The association between pregnancy status and SI was modified according to the recent clinical diagnosis of depression (interaction term: OR = 41.72, 95% CI: 5.64-308.45, p < 0.001). Our findings indicated that among nondepressed women, pregnancy status seems to decrease the probability of SI. Additionally, SI is associated with a vulnerable profile that includes being an adolescent, having an unpartnered/not married status, lower family income, lower education, and a recent clinical diagnosis of depression.

CONCLUSION

SI is a common problem for reproductive-age women. In the presence of a recent depression clinical diagnosis, pregnancy increases the risk of SI. Management of SI among pregnant women should correctly identify sociodemographic risk factors and the presence of a recent clinical diagnosis of depression.

A 70% Reduction in Mosquito Populations Does Not Require Removal of 70% of Mosquitoes

We added a vector control component to our existing abundance model to simulate intensive vector control in Puerto Rico. Removing 20-30% of gravid females in the model matches observed 60-80% reductions. The model's capacity to reproduce vector control increases its utility for planning and evaluation strategies.

Gravid Culex pipiens Exhibit A Reduced Susceptibility to Ultra-Low Volume Adult Control Treatments Under Field Conditions

In July and August of 2018, a field trial was conducted to examine the effectiveness of the North Shore Mosquito Abatement District's operational ultra-low volume (ULV) adulticide program. Two study sites were selected in Skokie, IL, and treated by truck-based ULV with d-phenothrin and prallethrin synergized with piperonyl butoxide over the course of a month. Natural mosquito populations were sampled via Biogents (BG)-counter baited with CO₂ or Alfalfa infusion. The results from this study demonstrate that host-seeking mosquitoes were reduced by 65.3% after ULV treatment while gravid mosquitoes were reduced by only 29.2%. In addition, host-seeking mosquitoes rebounded dramatically (303.1%) 3 days posttreatment while gravid mosquitoes did not (5.7%). Based on the differential effect between gravid and host-seeking mosquitoes, we concluded that the gonotrophic cycle and timing of ULV adulticide operations are important factors affecting the resistance of West Nile virus vectors to pyrethroid exposures.

Identification of gravid mosquitoes from changes in spectral and polarimetric backscatter cross sections

Improving the survey of mosquito populations is of the utmost importance to further enhance mitigation techniques that protect human populations from mosquito-borne diseases. While mosquito populations are generally studied using physical traps, stand-off optical sensors allow to study insect ecosystems with potentially better spatial and temporal resolution. This can be greatly beneficial to eco-epidemiological models and various mosquito control programs. In this contribution, we demonstrate that the gravidity of female mosquitoes can be identified from changes in their spectral and polarimetric backscatter cross sections. Among other predictive variables, the wing beat frequency and the depolarization ratio of the mosquito body allows for the identification of gravid females with a precision and recall of 86% and 87%, respectively. Since female mosquitoes need a blood meal to become gravid, statistics on gravidity is of prime importance as only females that have been gravid might carry infectious diseases. In addition, it allows to detect possible breeding habitat, predict a potential increase in the mosquito population and provide a better overall understanding of the ecosystem dynamics. As a result, targeted and localized mitigation techniques can be used, reducing the cost and improving the efficiency of mosquito population control.

How to walk carrying a huge egg? Trade-offs between locomotion and reproduction explain the special pelvis and leg anatomy in kiwi (Aves; Apteryx spp.)

Kiwi (Aves; genus Apteryx) are famous for laying an enormous egg in comparison with their relatively small body size. Considering the peculiar gait of this flightless bird, we suspected the existence of morpho-functional trade-offs between reproduction and locomotion. To understand how structural constraints, imposed by a large egg size, might influence the terrestrial locomotion of Apteryx, we analysed the anatomy of the limb osteomuscular system in two species of kiwi (Apteryx mantelli and Apteryx owenii). We performed detailed dissections and brought to light specific anatomical features of kiwi, in comparison with other ratites and neognathous birds. Our osteological study revealed a strongly curved pelvis, a rigid tail, and enlarged ribs. Our myology study showed an unusual location of the caudofemoralis muscle origin and insertion. The insertion of the pars pelvica along the entire caudal face of the femur, contrasts with the proximal insertion usually seen in other birds. Additionally, the pars caudalis originates along the entire tail, whereas it only inserts on the uropygium in the other birds. To interpret these specificities from a functional point of view, we built three-dimensional osteomuscular models based on computed tomography scans, radiographies and our dissections. We chose three postures associated with reproductive constraints: the standing position of a gravid compared with a non-gravid bird, as well as the brooding position. The 3D model of the brooding position suggested that the enlarged ribs could support the bodyweight when leaning on the huge egg in both males and females. Moreover, we found that in gravid females, the unusual shape of the pelvis and tail allowed the huge egg to sit ventrally below the pelvis, whereas it is held closer to the rachis in other birds. The specific conformation of the limb and the insertions of the two parses of the caudofemoralis help to maintain the tail flexed, and to keep the legs adducted when carrying the egg. The caudal location of the hip and its flexed position explains the long stance phase during the strange gait of kiwi, revealing the functional trade-off between reproduction and locomotion in this emblematic New Zealand bird.

A Small-Scale Investigation Into the Effect of A Larvicidal Oil On Oviposition Site Preference By Aedes aegypti

Larvicidal oils can be used to control immature Aedes aegypti and other pestiferous mosquitoes. To test whether oil-based larvicides also act as oviposition deterrents, indoor and semi-field trials were conducted at the Navy Entomology Center of Excellence in Jacksonville, FL. In both studies, treatment cages consisted of oviposition cups lined with seed germination paper as an oviposition substrate and filled with 1-wk-old southern live oak ( Quercus virginiana) leaf litter-infused water. Treatment cages consisted of 2 cups treated with CocoBear™ Mosquito Larvicidal Oil, while 2 cups were untreated. Control cages contained oviposition cups with only oak leaf litter-infused water. Gravid Ae. aegypti were released into cages and allowed to oviposit for 24 h, after which eggs were counted. The number of eggs deposited in treatment and control cages was not significantly different (indoor P = 0.0865; outdoor P = 0.9765). However, the number of eggs deposited in untreated cups was significantly greater than that deposited in treated cups within treatment cages (indoor P < 0.0001; outdoor P = 0.0050). These results suggest that the presence of the larvicidal oil CocoBear may cause gravid female Ae. aegypti to seek alternative oviposition sites.