Female Abundance Research Articles

I know it when I see it: Incidence, timing and intensity of immigration in spruce budworm

Abstract Incidence of immigration in spruce budworm Choristoneura fumiferana (Lepidoptera: Tortricidae) was inferred with rules of thumb and numerical thresholds contrasting closed populations (residents >> migrants) versus populations subjected to major immigration event, based on attributes of daily time series of abundance at light traps (abundance, statistical mode, sex ratio and protandry level). The data set included time series with known migration event (Bas St‐Laurent, QC, 2013), which were used to calibrate numerical thresholds associated with immigration. The study site on west coast of Newfoundland provided a natural laboratory to infer long‐range immigration due to geographic isolation from the mainland, proximity to the coast and low population density at onset of the study. Time series between 2014 and 2016 exhibited trends consistent with scenario of closed population, including low numbers of budworms, limited variation in day‐to‐day abundance and strong level of protandry (males fly seasonally earlier than females). Time series with candidate major immigration event (Bas St‐Laurent 2013, Sally's Cove 2017, 2018) displayed specific combinations of parameters, including: (a) sharp increment (>one order of magnitude) in abundance of both males and females from one day to the next (statistical mode, approximately corresponding to timing of migration); (b) pure (100%) convergence of pulse detection interval (post‐immigration period when migrants with nonzero survival rate are collected at light traps) across traps for males and females and (c) overall absence of protandrous flight. Parameters related to immigration thresholds highlighted that females are more likely to migrate than males, as indicated by increased ratio of females per male during pulse detection interval. Aerial collection of adult spruce budworms with helikite in 2019 confirmed the preponderance of females among true migrants.

Agricultural landscape affects sex‐specific differences in the abundance of Drosophila suzukii in raspberry orchards

AbstractIn recent decades, the spotted wing Drosophila (SWD) (Drosophila suzukii), an invasive pest, has caused a great deal of damage to fruit crops. There is therefore an urgent need to develop strategies to control the populations of this species. It has been found that the landscape context can buffer or increase the severity of pest outbreaks in agriculture, and it is important to understand how this process works in SWD for all crops. Given this background, we investigated the influence of forest on SWD populations in raspberry orchards and surrounding agricultural land. We selected 10 locations in the central part of Slovenia, five of which were closer than 200 m from the forest edge and five of which were more than 200 m from the forest edge. We collected SWD adults in three habitat types per location from the end of June until the end of October 2020. The results showed that forest harboured a larger SWD population than orchards and agricultural land. Over the season, the number of individuals increased exponentially over time, and the difference between forest and other habitat types increased. The distance from the forest had a negative effect on the abundance of SWD. There was a difference in abundance observed between males and females, with males being less abundant farther away from the forest than females. However, the distance from the forest only had a negative effect on the abundance of females in September. Based on the results, we propose potential measures for the control of SWD in raspberry orchards.

Attraction waves of male fiddler crabs: A visual display designed for efficacy

Animal signals can be very complex, particularly those used in mate attraction. They can contain multiple elements that have different functions- some based on signal efficacy and some on signal content. In this study, we show that the fiddler crab, Austruca lactea, produces a complex mating signal with three sequential wave types, each given in a different context. We suggest that the first two wave types are alerting signals that are designed for signal efficacy. They function to draw female attention before the male switches to the content-carrying signal that is used for female mate choice. We show that males produce ‘broadcast waves’ when no female is visible to them. These waves are given steadily, but at a slow rate, throughout the diurnal low tide mating period. They are effective at drawing the attention of the rare and unpredictable mate-searching females. Once a distant female becomes visible to the male, he switches to producing ‘directed waves’; they are given at a faster rate and their temporal distribution matches the abundance of mate-searching females. Both broadcast and directed waves appear to be designed for signal efficacy rather than signal content. They are alerting signals that draw female attention to the presence and location of the male. The third wave type is the courtship wave; it is given when the female is close to the male and is equivalent to the typical information-carrying mate choice wave found in other fiddler crab species.

Young-Of-The-Year Stone Crab (Genus Menippe) Recruitment in the Gulf of Mexico Off Florida: Key Shallow-Water Hotspots

Knowledge of juvenile recruitment (defined here as the quantitative addition of early benthic life stages to a local population) is important for conserving heavily harvested species and their critical habitats. Stone crabs (genus Menippe) are commercially and ecologically important throughout the Gulf of Mexico nearshore waters off Florida, but very little is known about their recruitment. Using standard commercial stone crab traps, megalopal and postsettlement juvenile (collectively, young-of-the-year, “YOY”) stone crabs were sampled at multiple spatial scales and for multiple stone crab generations to characterize geographical, seasonal, and interannual variation in their distribution and relative abundance (numbers collected on traps) in the Gulf of Mexico off peninsular Florida and north of the Florida Keys (the “Florida Gulf”). The influences of potentially relevant oceanographic and biological variables [temperature, salinity, benthic community on the traps (trap fouling community), depth, distance from shore] on YOY stone crabs were investigated at locations distributed throughout the study area. Trap fouling communities had never been analyzed in detail prior to this study; an importance index was developed to quantify the seasonality, commonality, and density of the fouling communities and organisms composing the communities. Continuous, long-term data from the Tampa Bay location allowed investigation of the effects of biological relationships [relative abundance of female Menippe carrying eggs (ovigerous), occurrences of red tide (Karenia brevis, a toxic dinoflagellate) blooms] and meteorological events [tropical cyclones, El Niño Southern Oscillation (ENSO) occurrences] on temporal patterns of variation in recruitment. High relative abundances of YOY stone crabs were collected off peninsular Florida from dense, complex benthic biota that grew on crab traps located off large, pristine estuaries in relatively turbid water less than 5 m deep, where salinity ranged 24–36 and water temperature averaged 29°C–32°C. Two major recruitment locations, stable through decades, consistently accounted for approximately 50% of the YOY stone crabs collected; two secondary recruitment locations similarly accounted for another 25%. Relative abundance of YOY stone crabs was highest nearshore at the major recruitment locations, particularly during years of high relative abundance. Approximately 65%–75% of the recruits were collected August to October; however, the timing of both peak relative abundance and lowest relative abundance shifted to later in the year as latitude decreased. Patterns of change among months in relative abundance differed among locations within years and among years within locations. Water temperature, salinity, and trap fouling community were the important determinants of temporal and spatial variation in YOY stone crab relative abundance; depth and distance from shore were also important in areas where they varied notably among stations within locations and across broader expanses of the study area. At Tampa Bay, a sharp increase in relative abundance of ovigerous females in spring was followed by a similarly sharp increase in YOY stone crab relative abundance (principally stage 3–5 crabs) 3 mo later; whereas a sharp decrease in ovigerous female relative abundance in autumn was followed by a similarly sharp decrease in YOY stone crab relative abundance 1 mo later. Coincidence of the normal autumnal decrease in YOY stone crab relative abundance with red tides and tropical cyclones prevented assigning clear relationships between seasonal change in relative abundance and these potential external influences. Annual decreases in relative abundance were significantly related to the occurrence of tropical cyclones that came near Tampa Bay during the previous year. Twice, confluences of multiple hurricanes, timely red tides, and ENSO events were followed by nearly complete, 1- to 2-y recruitment collapses. In contrast, a single meteorologically and oceanographically highly anomalous year coincided with exceptionally high abundances of both YOY and ovigerous female stone crabs. A relationship between YOY stone crabs and subsequent fishery harvest was not evident, possibly due to a variety of fishery practices. Because stone crabs are subjected to intense fishing pressure throughout the Florida Gulf, the YOY stone crab recruitment grounds and their associated estuaries should be protected from the effects of development, agriculture, aquaculture, and commercial and recreational crabbing.

The feature of cervical microbiota associated with the progression of cervical cancer among reproductive females

ObjectivesThe aim of this study was to characterize cervical microbiome feature of reproductive-age women in the progression of squamous intraepithelial lesions (SIL) to cervical cancer. MethodsWe characterized the 16S rDNA cervical mucus microbiome in 94 participants (age from 18 to 52), including 13 cervical cancer (CA), 31 high-grade SIL (HSIL), 10 low-grade SIL (LSIL), 12 HPV-infected (NH) patients and 28 healthy controls (NN). Alpha (within sample) diversity was examined by Shannon and Simpson index, while Beta (between sample) diversity by principle coordinate analysis (PCoA) of weighted Unifrac distances. Relative abundance of microbial taxa was compared using Linear Discriminant Analysis Effect Size (LEfSe). Co-occurrence analysis was performed to identify correlation among marker genera, and Phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) to explore functional features and pathways of cervical microbiota. ResultsAlpha diversity(p < 0.05) was higher in severer cervical pathology with lower relative abundance of Lactobacillus as well as higher of anaerobes. Beta diversity (p < 0.01) was significantly different. Marker genera were identified including Porphyromonas, Prevotella and Campylobacter of CA and Sneathia of HSIL. The correlation of differential functional pathways with Prevotella was opposite to that with Lactobacillus. ConclusionOur study suggests differences in cervical microbiota diversity and relative abundance of reproductive-age females in different stages of cervical carcinogenesis. Marker genera might participate in the lesion progression and will be helpful for diagnosis, prevention and treatment. These findings may lead the way to further study of the cervical microbiome in development of cervical cancer.

Field Efficacy of Larvivorous Fish and Pyriproxyfen Combined with Community Engagement on Dengue Vectors in Cambodia: A Randomized Controlled Trial.

ABSTRACT.Evidence on the effectiveness of low-cost, sustainable biological vector control tools for Aedes mosquitoes is limited. Therefore, the purpose of this trial was to estimate the impact of guppy fish in combination with the larvicide pyriproxyfen (PPF) (Sumilarv® 2MR) and communication for behavioral impact (COMBI) activities to reduce entomological indices in Cambodia. In this cluster randomized, controlled superiority trial, 30 clusters comprised of one or more villages each was allocated in a 1:1:1 ratio to receive either 1) all three interventions (guppies, PPF, and COMBI), 2) two interventions (guppies and COMBI), or 3) control (standard vector control). Entomological surveys among 40 randomly selected households per cluster were carried out quarterly. The primary outcome was the population abundance of adult female Aedes mosquitoes trapped using adult resting collections. In the primary analysis, adult female Aedes abundance and mosquito infection rates was aggregated over follow-up time points to give a single rate per cluster. These data were analyzed by negative binomial regression, yielding abundance ratios (ARs). The number of Aedes females was reduced roughly by half compared with the control in both the guppy, PPF, and COMBI arm (AR = 0.54; 95% CI, 0.34–0.85; P = 0.0073); and the guppy and COMBI arm (AR = 0.49; 95% CI, 0.31–0.77; P = 0.0021). The effectiveness demonstrated and extremely low cost of including fish rearing in community-based health structures suggest they should be considered as a vector control tool as long as the benefits outweigh any potential environmental concerns. Sumilarv® 2MR was also highly accepted and preferred over current vector control tools used in Cambodia.

Seasonal Population Structure of the Copepod Temora turbinata (Dana, 1849) in the Kuroshio Current Edge, Southeastern East China Sea

The abundance of adult males, females, and copepodites, and sex ratio of a Temora turbinata population and seawater hydrology were studied from 2018 to 2019 in waters off northeast Taiwan, northwest Pacific Ocean. The hydrological parameters showed significant differences between sampling months caused by interactions of Kuroshio, East China Sea water, and the China Coastal Current. The highest average abundance was recorded from the June 2018 cruise with 2903.92 ± 3499.47 (inds. m−3), followed by a cruise in June 2019 with an average abundance of 1990.64 ± 1401.55 (inds. m−3). The sex ratio ranged between 0.25 and 2.33; the records were significantly higher in samples of June 2018 than during other sampling cruises (one-way ANOVA). The spatiotemporal distribution of T. turbinata showed a clear pattern of seasonal changes among sampling stations and distribution zones. Abundance of females and copepodites correlated significantly positive (r = 0.755, p &lt; 0.001), whereas sex ratio (r = 0.247, p = 0.119) did not correlate significantly. The present study revealed that the abundance of T. turbinate was highest in June and was positively correlated with seawater temperature; furthermore, this is the first time the in situ sex ratio of T. turbinata in western Pacific waters has been reported.

Evolutionary dynamics of the Trivers-Willard effect: A nonparametric approach.

The Trivers–Willard hypothesis (TWH) states that parents in good condition tend to bias their offspring sex ratio toward the sex with a higher variation in reproductive value, whereas parents in bad condition favor the opposite sex. Although the TWH has been generalized to predict various Trivers–Willard effects (TWE) depending on the life cycle of a species, existing work does not sufficiently acknowledge that sex‐specific reproductive values depend on the relative abundances of males and females in the population. If parents adjust their offspring sex ratio according to the TWE, offspring reproductive values will also change. This should affect the long‐term evolutionary dynamics and might lead to considerable deviations from the original predictions.In this paper, I model the full evolutionary dynamics of the TWE, using a published two‐sex integral projection model for the Columbian ground squirrel (Urocitellus columbianus). Offspring sex ratio is treated as a nonparametric continuous function of maternal condition. Evolutionary change is treated as the successive invasion of mutant strategies. The simulation is performed with varying starting conditions until an evolutionarily stable strategy (ESS) is reached.The results show that the magnitude of the evolving TWE can be far greater than previously predicted. Furthermore, evolutionary dynamics show considerable nonlinearities before settling at an ESS. The nonlinear effects depend on the starting conditions and indicate that evolutionary change is fastest when starting at an extremely biased sex ratio and that evolutionary change is weaker for parents of high condition. The results show neither a tendency to maximize average population fitness nor to minimize the deviation between offspring sex ratio and offspring reproductive value ratio.The study highlights the importance of dynamic feedback in models of natural selection and provides a new methodological framework for analyzing the evolution of continuous strategies in structured populations.

Disentangling the effect of sea temperature and stocking density on sea louse abundance using wavelets in a highly infested salmon farming area

Sea louse infestations are threatening the sustainability of the salmon farm industry worldwide; the southern marine ecosystem of Chile is one of the most affected areas. A highly infested management area located in the Los Lagos Region (42.5°S) has been regularly affected by Caligus rogercresseyi outbreaks during the spring-summer period since 2012. In this study, the effect of salmon stocking density and sea surface temperature on the temporal dynamics of juveniles and ovigerous females was analyzed at a regional scale using wavelets. Main periodic oscillations were detected for ovigerous female time series centered at periods equal to 52 weeks (1-year cycle) and 107 weeks (2-year cycle), which are associated with, respectively, the annual sea louse outbreaks occurring during the warmest season (spring-summer), and the periodic increase of lice driven by an increase in salmon stocking density as the farming cycle progresses. The 1-year and 2-year cycles explained between 10%–20% and between 25%–52% of the variance of ovigerous females, respectively. Wavelet coherence and phase analysis showed a significant association between sea surface temperature and ovigerous female abundance associated with the 1-year cycle with a time lag (in weeks) very close to the louse generation cycle. Coherence between stocking density and ovigerous female abundance was significant, associated with the 2-year cycle. These results suggest the existence of a continuous year-round effect of temperature on louse development rate which becomes more relevant during spring-summer outbreaks, specially at high stocking density levels. Two main stocking density (SD)-sea surface temperature (SST) scenarios were identified, and the location and size of major outbreaks at the high SD-high SST scenario were well predicted using ovigerous female integrated 1-year and 2-year cycles. Future studies should be focused on the development of a stocking density regulation model, mainly depending on SD and SST periodic variability, in order to prevent maximum levels of the two factors from coinciding, because this condition is inevitably followed by major ovigerous female outbreaks in this area.

Predatory mite instars (Acari, Mesostigmata) and decomposing tree leaves in mixed and monoculture stands growing on a spoil heap and surrounding forests

In the past, ecological research mainly omitted the sexual and developmental variability of mite communities, and therefore could not fully reflect the actual state and function of mite communities in the ecosystems studied. The aim here was to analyze how habitat conditions (mixed vs. monoculture stands) and single-species litter of 14 tree species (in mixed stands) affect the sex and developmental stages of Mesostigmata mites living on the decomposing litter. The research was conducted in 2011–2016, at the Bełchatów Lignite Mine external spoil heap (Central Poland) in mixed stands growing on the spoil heap, as well as in pine and birch monoculture stands growing on the spoil heap and an adjacent forest area. We found significant influences of habitat on females, males and juveniles. Additionally, we found that soil mean temperature had a significant effect on males and juveniles, but not on females. Moreover, despite the insignificant influence of litter species on mite communities, we found that percentage litter mass loss significantly affected female and juvenile mites. Taking into account habitat type, the percentage litter mass loss significantly affected female and male mites, but not juveniles. The mite abundance calculated per dry litter mass usually gradually increased during decomposition. Interestingly, the highest mean female, male and juvenile abundances were recorded in birch stands growing on the adjacent forest area; however, juvenile mites were also very numerous in mixed stands on spoil heap. Therefore, our results confirm that mixed stands on post-mining areas are a potentially better habitat for development of mesostigmatid communities compared to monocultures, among others by relatively higher humidity and lower temperatures.

Variable coverage in an Autocidal Gravid Ovitrap intervention impacts efficacy of Aedes aegypti control.

Control of the arboviral disease vector Aedes aegypti has shown variable levels of efficacy around the globe. We evaluated an Autocidal Gravid Ovitrap (AGO) intervention as a stand‐alone control tool for population suppression of A. aegypti in US communities bordering Mexico.We conducted a cluster randomized crossover trial with weekly mosquito surveillance of sentinel households from July 2017 to December 2018. The intervention took place from August to December of both years. Multilevel models (generalized linear and additive mixed models) were used to analyse the changes in population abundance of female A. aegypti.We observed that female populations were being suppressed 77% (2018) and four times lower outdoor female abundance when AGO coverage (number of intervention AGO traps that surrounded a sentinel home) was high (2.7 AGOs/house). However, we also observed that areas with low intervention AGO coverage resulted in no difference (2017) or slightly higher abundance compared to the control. These results suggest that coverage rate might play a critical role on how populations of female A. aegypti are being modulated in the field. The lack of larval source habitat reduction and the short duration of the intervention period might have limited the A. aegypti population suppression observed in this study. Synthesis and applications. The mosquito, A. aegypti, is a public health concern in most tropical and subtropical regions. With the rise of insecticide resistance, the evaluation of non‐chemical tools has become pivotal in the fight against arboviral disease transmission. Our study shows that the AGO intervention, as a stand‐alone control tool, is limited by its coverage in human settlements. Vector control programmes should consider, that if the target coverage rate is not achieved, measures will be ineffective unless coupled with other control approaches. Although our multilevel modelling was focused on A. aegypti and the AGO, the approach can be applied to other mosquito vector species.

Ecological, Social, and Other Environmental Determinants of Dengue Vector Abundance in Urban and Rural Areas of Northeastern Thailand.

Aedes aegypti is the main vector of dengue globally. The variables that influence the abundance of dengue vectors are numerous and complex. This has generated a need to focus on areas at risk of disease transmission, the spatial-temporal distribution of vectors, and the factors that modulate vector abundance. To help guide and improve vector-control efforts, this study identified the ecological, social, and other environmental risk factors that affect the abundance of adult female and immature Ae. aegypti in households in urban and rural areas of northeastern Thailand. A one-year entomological study was conducted in four villages of northeastern Thailand between January and December 2019. Socio-demographic; self-reported prior dengue infections; housing conditions; durable asset ownership; water management; characteristics of water containers; knowledge, attitudes, and practices (KAP) regarding climate change and dengue; and climate data were collected. Household crowding index (HCI), premise condition index (PCI), socio-economic status (SES), and entomological indices (HI, CI, BI, and PI) were calculated. Negative binomial generalized linear models (GLMs) were fitted to identify the risk factors associated with the abundance of adult females and immature Ae. aegypti. Urban sites had higher entomological indices and numbers of adult Ae. aegypti mosquitoes than rural sites. Overall, participants’ KAP about climate change and dengue were low in both settings. The fitted GLM showed that a higher abundance of adult female Ae. aegypti was significantly (p < 0.05) associated with many factors, such as a low education level of household respondents, crowded households, poor premise conditions, surrounding house density, bathrooms located indoors, unscreened windows, high numbers of wet containers, a lack of adult control, prior dengue infections, poor climate change adaptation, dengue, and vector-related practices. Many of the above were also significantly associated with a high abundance of immature mosquito stages. The GLM model also showed that maximum and mean temperature with four-and one-to-two weeks of lag were significant predictors (p < 0.05) of the abundance of adult and immature mosquitoes, respectively, in northeastern Thailand. The low KAP regarding climate change and dengue highlights the engagement needs for vector-borne disease prevention in this region. The identified risk factors are important for the critical first step toward developing routine Aedes surveillance and reliable early warning systems for effective dengue and other mosquito-borne disease prevention and control strategies at the household and community levels in this region and similar settings elsewhere.

Estimating Abundance of Desert Mule Deer Using Fecal DNA–Based Capture-Recapture

Wildlife conservationists and managers often need to estimate abundance and demographic parameters to monitor the status of populations, and to ensure that these populations are meeting management goals. DNA capture-recapture surveys have become increasingly common in situations where physical surveys are consistently difficult or counts are small or variable. Desert mule deer (Odocoileus hemionus eremicus) inhabit rugged terrain, occur at low population densities, and demonstrate cryptic behaviors, making monitoring and assessing population status difficult. We assessed the effectiveness of a fecal DNA–based capture-recapture method for estimating abundance and survival of desert mule deer. We designed and implemented a fecal DNA sampling design focused at water sources during the dry season (June–July) of 2015–2017 in the Little Chuckwalla Mountains (study area ∼968 km2) located in the Sonoran Desert of southeastern California. We conducted 6, 5, and 4 surveys in 2015, 2016, and 2017, respectively. We used the capture-recapture data in the POPAN open-population model to estimate abundance and the Cormack–Jolly–Seber model to estimate annual survival. We detected 234, 193, and 211 unique individuals in 2015, 2016, and 2017, respectively. Over the 3-year study, population abundance estimates ranged from 386 in 2015 (95% CI, 264–509) to 301 in 2017 (95% CI, 260–342). Precision (i.e., coefficient of variation [CV]) of male and female abundance estimates ranged from 7% to 16%, and CV for males and females combined ranged from 5% to 15%. Annual apparent survival for females and males was 0.91 (95% CI, 0.59–0.98) and 0.71 (95% CI, 0.51–0.85), respectively. We concluded that fecal DNA–based capture-recapture is an effective method for estimating abundance and survival of desert mule deer. This approach could be expanded to encompass additional areas adjacent to our study site, with the potential to monitor the larger metapopulation of desert mule deer in the Sonoran Desert of California. More generally, DNA mark-recapture may be widely applicable to other species that congregate around water sources (or any required resource) during part of the year. Results from this study will be useful for developing population monitoring plans and for studies evaluating the effects of human development or environmental factors on desert mule deer and other desert ungulates.

Enigmatic Near‐Extirpation in a Boreal Toad Metapopulation in Northwestern Montana

ABSTRACTNorth America's protected lands harbor biodiversity and provide habitats where species threatened by a variety of stressors in other environments can thrive. Yet disease, climate change, and other threats are not limited by land management boundaries and can interact with conditions within protected landscapes to affect sensitive populations. We examined the population dynamics of a boreal toad (Anaxyrus boreas boreas) metapopulation at a wildlife refuge in northwestern Montana, USA, over a 16‐year period (2003–2018). We used robust design capture‐recapture models to estimate male population size, recruitment, and apparent survival over time and in relation to the amphibian chytrid fungus (Batrachochytrium dendrobatidis). We estimated female population size in years with sufficient captures. Finally, we examined trends in male and female toad body size and condition. We found no evidence of an effect of disease or time on male toad survival but detected a strong negative trend in recruitment of new males to the population. Estimates of male and female abundance decreased over time. Body size of males and females was inversely related to estimated population size, consistent with reduced recruitment to replace adults, but body condition of adult males was only weakly associated with abundance. Together, these results describe the demography of a near‐extirpation event, and point to dramatic decreases in the recruitment of new individuals to the breeding population as the cause of this decline. We surmise that processes related to the restoration of historical hydrology within the refuge adversely affected amphibian breeding habitat, and that these changes interacted with disease, life history, and other factors to restrict the recruitment of new individuals to the breeding population over time. Our results point to challenges in understanding and predicting factors that influence population change and highlight that current metrics for assessing population status can have limited predictive ability. Published 2021. This article is a U.S. Government work and is in the public domain in the USA.

Do sexual gonadic maturity and age determine habitat occupancy ofCanthon cyanellusLeConte, 1859 (Coleoptera: Scarabaeidae)?

AbstractHigh-quality habitats presumably have the resources required to sustain relatively high rates of survival and reproduction. We assessed how habitat type and local environmental conditions determine the distribution of individuals ofCanthon cyanellus(Coleoptera: Scarabaeidae), an eurytopic dung beetle, according to age category and sexual gonadic maturity. Beetles were surveyed in forest fragments, live fences, and pastures in Mexico. Individuals were categorised into six age categories according to the glandular volumes in males and oocyte number and length in females. Mature females in forest fragments were the most abundant females found among the habitats. Air humidity and soil hardness were positively and negatively related to mature female abundance, respectively. Mature beetles were the most abundant among males, and higher abundance of males occurred in forest fragments than in live fences and pastures. Light quantity was negatively related to the abundance of young males. Compared to forest fragments, females in pastures had larger oocytes. However, sites with higher soil hardness and air humidity had females with lower numbers of oocytes. Our results demonstrate that, althoughC. cyanellusoccurs across a wide range of habitats, forest habitats might host sexually mature individuals, which translates into more effective individual dispersion and potential reproduction.

The Eco-Bio-Social Factors That Modulate Aedes aegypti Abundance in South Texas Border Communities

Simple SummaryThe Aedes aegypti mosquito is distributed worldwide and has become a major public health concern due to its proclivity for the urban environment, human feeding behavior, and ability to transmit agents of diseases such as Zika, chikungunya, and dengue. In the continental United States, the region known as the Lower Rio Grande Valley is one of the few areas with local mosquito transmission of these pathogens transmitted by Ae. aegypti. With limited resources for mosquito control in this region, understanding the ecological, biological, and social factors that affect Ae. aegypti population can help guide and improve current control efforts. We were able to observe widespread knowledge regarding Zika, but with very low importance given to mosquitoes as a problem. We found that the presence of window-mounted air conditioning units, number of windows and doors, characteristics of the property, and presence of children in the household all influenced the abundance of Ae. aegypti. The current results not only show a need for improved community engagement for increasing disease and mosquito risk awareness, but also provide risk factors that can guide current vector control activities. Aedes aegypti control requires dedicated resources that are usually scarce, limiting the reach and sustainability of vector control programs. This generates a need to focus on areas at risk of disease transmission and also understand the factors that might modulate local mosquito abundance. We evaluated the eco-bio-social factors that modulate indoor and outdoor relative abundance of female Ae. aegypti in communities of South Texas. We conducted housing quality and Knowledge Attitudes and Practices surveys in households that were part of a weekly mosquito surveillance program in November of 2017 and 2018. Our results showed widespread knowledge of mosquitoes and Zika virus by our participants. However, less than 35% considered them as serious problems in this region. The presence of window-mounted air conditioning units increased the risk of female mosquito relative abundance indoors. An increase in outdoor relative abundance was associated with larger properties and a higher number of children between 6 to 17 years of age. Interestingly, we observed that an increasing number of children <5 years of age modulated both indoor and outdoor relative abundance, with a 52% increase indoors and 30% decrease outdoors. The low perception of mosquito and disease risk highlights engagement needs for vector-borne disease prevention in this region. The identified risk factors can help guide public health officials in their efforts to reduce human and vector contact.

Estimation of key population parameters and MSY-based reference points for sidestripe shrimp (Pandalopsis dispar) in the Fraser River Delta, British Columbia

Fishery-independent trawl survey data were used to estimate biological parameters for Sidestripe shrimp, Pandalopsis dispar, in the Fraser River delta of British Columbia. Sidestripe shrimp is a short-lived protandric hermaphrodite. They first mature as males, then transition into females in their second year, and then mature as females in their third year. Taking advantages of this unique life history, we developed a method of estimating individual ages based on life stages identified during surveys to produce a growth model for Sidestripe shrimp. We also estimated the natural mortality rate by comparing the abundance of females in one survey with the abundance of mature males in the previous year’s survey, after taking into account fishery removals of mature males between the two consecutive years. Further, we found a positive correlation between the biomass of spawned-out females and the abundance of mature males, constructing a stock-recruitment model for Sidestripe shrimp. MSY-based reference points were then derived accounting for growth, natural mortality and the stock-recruitment relationship. These reference points may be further used to assess stock status and formulate harvest control rules for the management of the Sidestripe shrimp stock.

Ontogenetic Habitat Use and Density of the Green Lizard (Lacerta bilineata) in Contrasted Landscapes in France and Italy

Habitat modification is a major factor in the decline of reptile populations. The degree of the decline has been shown to be directly related to the intensity of habitat modification. Farming practices and urbanization are just two of the factors involved indicating that the development of practices that minimize or cancel anthropogenic impacts is urgently needed to prevent further declines. This requires knowledge of population ecology of reptiles in both disturbed and pristine habitats. In this paper, we describe aspects of green lizard (Lacerta bilineata) population ecology in a forest–pasture relatively pristine mosaic habitat in central Italy and a fragmented habitat in western France. In Italy, habitat niche overlap was very high between males and females but very low between males and juveniles. For male and female abundances, general linear models showed that the adult abundances increased with the increase of Rubus bushes, whereas juvenile abundance increased with the increase of Spartium bushes. Contingency table analysis showed that juveniles were also much more frequently observed in grasslands than adults of either sexes. The observed ontogenetic structural niche pattern was likely due to intraspecific competition avoidance, competition interference, and cannibalism. The persistence of the same patterns across years demonstrates a temporal stability of the ontogenetic structural niche pattern. Over the length of the study period, population densities were stable in the Italian population, but densities were much higher by around five times in the hedgerow in the fragmented habitat in France. In the hedgerow, monthly lizard presence was uneven, with the greatest number of sightings in June and July. Overall, our study provided no support for the notion that lizard abundance/density should be lower in modified compared to unmodified habitats, and clearly revealed that a careful management of the hedgerows is crucial for the conservation of this lizard species in agro-forest ecosystems.

Host plant water deficit stress impairs reproduction and development of the galling fly (Parafreutreta regalis), a biological control agent of Cape-ivy (Delairea odorata)

Drought leading to water deficit stress is known to reduce performance of galling insects. The shoot tip-galling fly Parafreutreta regalis has been released for biological control of Cape-ivy (Delairea odorata) in California. Lack of moisture during the dry season causes wilting of Cape-ivy shoots, and subsequent reduced host quantity and quality could influence the fly’s ability to multiply and establish. We imposed water deficit stress on potted Cape-ivy plants, then measured the plant’s and insect’s response to water deficit compared to fully-watered plants. Water deficit stress was imposed during female oviposition (short-term), gall development (long-term), or full insect life cycle (long-term). Plants subjected to long-term water deficit showed declines in shoot growth, leaf area, and total biomass. In choice tests, 72% fewer galls were found on water deficit stressed plants, but there was no difference in the numbers of insects per gall. In no-choice tests, long-term water deficit reduced the number and size of galls by up to 51% and 39%, respectively, and puparia inside the galls were up to 35% smaller. Long-term water deficit also increased the time required for the insect to complete its life cycle (egg to adult) by about 10 days, and up to 80% fewer adults emerged, decreasing the fly’s rate of increase by up to five-fold. Our study shows that P. regalis will oviposit and develop successfully on water deficit-stressed plants, but declines in female preference, insect development and abundance could inhibit fly field establishment and/or population growth under climatic drought conditions.

Community deployment of a synthetic pheromone of the sand fly Lutzomyia longipalpis co-located with insecticide reduces vector abundance in treated and neighbouring untreated houses: Implications for control of Leishmania infantum.

The rising incidence of visceral leishmaniasis due to Leishmania infantum requires novel methods to control transmission by the sand fly vector. Indoor residual spraying of insecticide (IRS) against these largely exophilic / exophagic vectors may not be the most effective method. A synthetic copy of the male sex-aggregation pheromone of the key vector species Lutzomyia longipalpis in the Americas, was co-located with residual pyrethroid insecticide, and tested for its effects on vector abundance, hence potential transmission, in a Brazilian community study. Houses within eight defined semi-urban blocks in an endemic municipality in Brazil were randomised to synthetic pheromone + insecticide or to placebo treatments. A similar number of houses located >100m from each block were placebo treated and considered as "True Controls" (thus, analysed as three trial arms). Insecticide was sprayed on a 2.6m2 surface area of the property boundary or outbuilding wall, co-located within one metre of 50mg synthetic pheromone in controlled-release dispensers. Vector numbers captured in nearby CDC light traps were recorded at monthly intervals over 3 months post intervention. Recruited sentinel houses under True Control and pheromone + insecticide treatments were similarly monitored at 7-9 day intervals. The intervention effects were estimated by mixed effects negative binomial models compared to the True Control group. Dose-response field assays using 50mg of the synthetic pheromone captured a mean 4.8 (95% C.L.: 3.91, 5.80) to 6.3 (95% C.L.: 3.24, 12.11) times more vectors (female Lu. longipalpis) than using 10mg of synthetic pheromone. The intervention reduced household female vector abundance by 59% (C.L.: 48.7, 66.7%) (IRR = 0.41) estimated by the cross-sectional community study, and by 70% (C.L.: 56.7%, 78.8%) estimated by the longitudinal sentinel study. Similar reductions in male Lu. longipalpis were observed. Beneficial spill-over intervention effects were also observed at nearby untreated households with a mean reduction of 24% (95% C.L.: 0.050%, 39.8%) in female vectors. The spill-over effect in untreated houses was 44% (95% C.L.: 29.7%, 56.1%) as effective as the intervention in pheromone-treated houses. Ownership of chickens increased the intervention effects in both treated and untreated houses, attributed to the suspected synergistic attraction of the synthetic pheromone and chicken kairomones. The variation in IRR between study blocks was not associated with inter-household distances, household densities, or coverage (proportion of total households treated). The study confirms the entomological efficacy of the lure-and-kill method to reduce the abundance of this important sand fly vector in treated and untreated homesteads. The outcomes were achieved by low coverage and using only 1-2% of the quantity of insecticide as normally required for IRS, indicating the potential cost-effectiveness of this method. Implications for programmatic deployment of this vector control method are discussed.