Trap Nets Research Articles

Production of Rhizophora Mangrove Leaf Litter in The Sungai Bersejarah Mangrove Ecosystem, Siak Regency

The mangrove ecosystem is one of the coastal ecosystems that has important ecological roles and functions in supporting marine and fishery resources. Marine and fisheries resources are largely determined by the contribution of mangrove litter. The aims of this study was to determine the production of Rhizophora mangrove leaf litter in Sungai Bersejarah mangrove ecosystem, and to determine the value of environmental parameters related to litter. The research was conducted in January until March 2021 in Sungai Bersejarah mangrove area Kayu Ara Permai, Siak Regency. Line transect plot were used to calculate the density of Rhizophora. Rhizophora litter production was measured using the trap net method placed at three sampling site. Three litter trap nets measuring 1 m x 1 m are placed at each station. Rhizophora tree density ranges from 316 - 444 ind./ha. The production of Rhizophora mangrove leaf litter in Sungai Bersejarah mangrove ecosystem was 0.82 – 1.39 g/m2/day (3.00 – 5.09 ton/ha/year), average was 4.11 ton/ha/year. Analysis of variance test showed that there was a significant difference in Rhizophora leaf litter production between sampling points with different Rhizophora tree densities (p<0.05). Mangrove vegetation density has a moderate relationship (r=0.43) to the production of Rhizophora mangrove leaf litter. Environmental parameters indicate that the condition of the Sungai Bersejarah mangrove ecosystem is still good and can support the life of mangrove vegetation.

Species Variety of the Calf and Human-Attracted Mosquitoes in Southwest Iran.

Background:Any mosquito control methods requires precise information about population dynamics, variety, biology and mosquito habitat. This research assessed Culicid mosquitoes’ attraction to a human host and a calf to better understand their behavior.Methods:Adult mosquitoes were sampled in 22 weeks in southwestern Iran’s Nur Ali Village from May to October 2015. The mosquitoes were drawn to the person and calf as bait, while the unbaited trap was also used. A substantial statistical difference between attracted mosquitoes to the hosts was determined in the T-test.Results:Within 22 weeks, 29821 mosquitoes were captured. Only 9% were collected from the human baited net trap, 89.1% from the calf baited net trap, and 1.9% from the unbaited net trap. The number of collected female mosquitoes was statistically significantly higher using the calf baited net trap of the total mosquitoes, 916 were randomly identified at the species level by local identification keys. Of these, 63 were Anopheles stephensi (human: 16%, calf: 75% and unbaited: 9%), 83 An. pulcherrimus (human: 27%, calf: 60% and unbaited: 13%), 118 Aedes caspius (human: 24%, calf: 69% and unbaited: 7%), 493 Culex tritaeniorhynchus (human: 52%, calf: 37% and unbaited: 11%), 153 Cx. quinquefasciatus (human: 44%, calf: 47% and unbaited: 9%), and 6 Cx. theileri (human: 33%, calf: 50% and unbaited: 17%).Conclusion:The obtained results here provide useful insights into the mosquito population and the possibility of using this information as an essential part of integrated vector management regarding the reemergence of malaria or other mosquito-borne.

Entomological survey in two communes with residual malaria transmission in Gia Lai Province in the central highlands of Vietnam

BackgroundIn 2018, the National Malaria Control Programme in Vietnam switched from prioritizing malaria control to elimination. However, with the ongoing elimination programme, there are still areas where residual malaria transmission persists, including the central highlands. This entomological survey was conducted to evaluate Anopheles diversity and host-seeking activity of Anopheles vectors in two communes with very low malaria transmission in Gia Lai Province.MethodsAnopheles species were collected in Ia DReh commune and Ia KDam commune, Gia Lai Province in the central highlands of Vietnam. Collections were conducted using human-baited double net trap, light trap and manual aspiration collections around cattle sheds, in the dry and rainy season. Mosquito specimens were identified morphologically, and members of species complexes were distinguished molecularly. Mosquito night-feeding patterns were investigated during the dry and rainy seasons.ResultsOverall, 18,835 specimens including 19 taxa were collected in Ia KDam and Ia DReh communes. These included the primary malaria vectors, Anopheles dirus and Anopheles minimus, and other secondary vector species. Anopheles dirus was observed to be an anthropophilic species, whereas An. minimus and a number of secondary vectors were observed to be zoophilic. Anopheles vagus was the dominant species, followed by Anopheles sinensis and Anopheles peditaeniatus. The majority of specimens were collected in the rainy season due to the relatively large number of An. vagus, while An. peditaeniatus, An. dirus, Anopheles kochi, Anopheles monstrosus and Anopheles tessellatus were collected in greater numbers during the dry season. The peak of host-seeking activity for An. dirus, An. sinensis, and An. vagus was between 18.00 and 19.00 h.ConclusionThis study provided information on the diversity, seasonal prevalence and behaviour of Anopheles at the study sites. Identifying the diverse mosquito fauna in the central highlands of Vietnam allows species-specific control measures to be implemented by the National Programme to reduce malaria in areas of very low malaria transmission. The peak Anopheles host-seeking activity observed in this study was between 18.00 and 23.00 h, which highlights the need to better characterize Anopheles behaviour in this region of Vietnam to inform on vector control strategies.

Australian mosquito assemblages vary between ground and sub-canopy habitats

BackgroundThe surveillance and control of mosquito-borne diseases is dependent upon understanding the bionomics and distribution of the vectors. Most studies of mosquito assemblages describe species abundance, richness and composition close to the ground defined often by only one sampling method. In this study, we assessed Australian mosquito species near the ground and in the sub-canopy using two traps baited with a variety of lures.MethodsMosquitoes were sampled using a 4 × 4 Latin square design at the Cattana Wetlands, Australia from February to April 2020, using passive box traps with octenol and carbon dioxide and three variations of a sticky net trap (unbaited, and baited with octenol or octenol and carbon dioxide). The traps were deployed at two different heights: ground level (≤ 1 m above the ground) and sub-canopy level (6 m above the ground).ResultsIn total, 27 mosquito species were identified across the ground and sub-canopy levels from the different traps. The abundance of mosquitoes at the ground level was twofold greater than at the sub-canopy level. While the species richness at ground and sub-canopy levels was not significantly different, species abundance varied by the collection height.ConclusionsThe composition of mosquito population assemblages was correlated with the trap types and heights at which they were deployed. Coquillettidia species, which prefer feeding on birds, were mainly found in the sub-canopy whereas Anopheles farauti, Aedes vigilax and Mansonia uniformis, which have a preference for feeding on large mammals, were predominantly found near the ground. In addition to trap height, environmental factors and mosquito bionomic characteristics (e.g. larval habitat, resting behaviour and host blood preferences) may explain the vertical distribution of mosquitoes. This information is useful to better understand how vectors may acquire and transmit pathogens to hosts living at different heights.Graphical abstract

Analyzing the Current Status and Challenges of Coastal and Inshore Fisheries: A Review of the Impacts and the Legislative Improvements

Jung, B.-K. and Lee, N.-U., 2021. Analyzing the current status and challenges of coastal and inshore fisheries: A review of the impacts and the legislative improvements. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 604–608. Coconut Creek (Florida), ISSN 0749-0208. This study analyzed and reviewed the current status and challenges of coastal and inshore fisheries, which have the greatest impact on the continuous use of fishery resources and the protection and management of the marine ecosystem, and recommended measures to address such challenges. In particular, among the coastal and inshore stationary fishing boats and fisheries in the southern waters of South Korea, the current conditions and problems of gill net and fish trap fishery were analyzed by comparing them with the current fishing regulation system. Using a training ship, the waters where a large amount of fishing work involving coastal and inshore fishing vessels is being done were classified into A, B, and C and the waste fishing gears deposited in such waters were investigated in terms of their trawling means. In addition, the marine debris that was collected was directly identified.Through such practical field surveys and comparative analyses of the relevant information aimed at preventing disputes over fishing in coastal and inshore waters (which have been diverse and continuously occurring) as well as over the creation of waste fishing gears caused by deliberate or environmental factors, and their consequent adverse effects on the fishery resources ecosystem, this study presents a legislative improvement plan that could achieve the sustainable use of fishery resources and thus, promote the growth and development of fisheries in South Korea.

Population structure three species of Family Syngnathidae in Merowi River, Kecamatan Kembayan, Kabupaten Sanggau Kalimantan Barat

Pipe fish is a type of freshwater fish that has potential as ornamental fish. The research objective was to determine the status and habitat conditions of the Merowi River pipe fish as a member of Syngnathidae. The research was conducted from July to December 2019. The research stations were determined based on differences in existing environmental bases. Sampling had done randomly by using scoop net and umbrella fish trap. The data used include population density, age group,test Chi-Square and Principal Component Analysis (PCA). The results showed that 2 genera consisted of 3 species of pipe fish, as much 248 individu. Doryichthys deokhatoides 26 individu (0.042 Catch/Unit Efort); D. martensii 209 individu (0.34 Catch/Unit Efort); Microphis retzii 13 individu (0.02 Catch/Unit Efort). The length of the pipe fish ranged from 48.1 mm to 87.4 mm, and the ratio of male to female is 1: 1 (balanced). The presence of members of Syngnathidae in the Merowi River was effect by temperature and current velocity.

Diversity of Butterflies1 in the Core Zone of the Nature Reserve “El Tisey-La Estanzuela”, Estelí, Nicaragua: An Ecological Conservation Approach

Species of the Papilionidae, Pieridae, and Nymphalidae families of Lepidoptera were inventoried, diversity of habitats of the core area of the ecological reserve “El Tisey-La Estanzuela” (natural protected area) of Nicaragua was analyzed, and butterfly food guilds and efficiency of collection methods were determined. The study was at 11 sites: Bosque Pino Santa Rosa, Bosque Mixto Napoleón, Bosque Ripario, Café Almaciguera, Café Jalacate, Camino, Potrero Zontul, Potrero Cerro Tisey, Potrero Las Brisas, Roble Amarillo Cuchilla, and Roble Amarillo Zontul. Each habitat was systematically sampled using two collection methods (insect net and baited trap) once per week for 4 months (November 2014 to February 2015). An insect net was used with non-linear and linear transects and a trap was baited to attract butterflies for sampling. In total, 2,516 specimens in 18 subfamilies, 59 genera, 93 species, and 22 subspecies were collected. Adelpha paroeca paroeca Bates (Limenitinae), Diaethria pandama Doubleday (Eurytelinae), and Vanessa cardui L. (Nymphalinae) of the Nymphalidae family and Heraclides paeon thrason C. & R. Felder (Papilioninae) of the Papilionidae family were recorded for the first time in Nicaragua. The most abundant species were Hermeuptychia hermes Fabricius, Anartia fatima Fabricius, Heliconius charithonius L., Eurema salome jamapa Reakirt, and Eunica monima Stoll. Low richness and high species equity were recorded at “Bosque Mixto Napoleón” and “Roble Amarillo-Cuchilla”, while other habitats had high richness with low equity. The Potrero Cerro Tisey habitat had the greatest species equity. H. hermes was in 11 environments, and Camino and Potrero Zontul habitats had the greatest similarity of species. Basic information on biological diversity allows efforts to be focused on conserving species.

Using logbook‐based catch‐rate data to detect yellow eel population trends in the southern Baltic Sea

AbstractWithin recent years, a slight but significant increase of European eel Anguilla anguilla (L.) recruitment has been documented, but it remains questionable whether or not the increased recruitment levels resulted in higher eel numbers at the regional scale. To detect the changes in yellow eel numbers, logbook data covering a 15‐year time series of catch per unit effort (CPUE) data from the German Baltic Sea were analysed. Monthly mean catch rates were calculated for two different size classes for two passive gears: fyke and stationary trap nets. Change‐point analysis was applied to discover changes in the catch data. After a period of decreasing or constant catch rates, the fyke net data indicated that yellow eel numbers increased slightly in recent years in the Baltic Sea. Besides increasing numbers of immigrating juvenile eels, other population dynamics or conservation efforts might have added to the observed positive stock trend.

The diversity of insects in opened land utilization with a cultivation of Brachiaria mutica forage in ‘Sentrum Agraris Lotta’

An opened land which has been abandoned could be revitalized by forage cultivation could be a good alternative, but the extent to which the diversity of insects visiting and or engaging in this cultivation was not well known. The presence of insects in Brachiaria mutica cultivation site could play an integrated role on various components of the environment. This study aimed to determine the level of insect diversity found in B. mutica grass cultivation sites on opened land without restriction of solar radiation. The identification of insects in this study was carried out at the family level. The collection of insect visiting and or engaging at the B. mutica cultivation site was carried out at 10 points on the transect line using a pitfall-trap at 5 points A and a swing net trap at 5 points B. The insect diversity was calculated based on the Shannon-Wiener index calculation. The results obtained were fourteen insect families detected at the research location, and the most widely monitored were from the Formicidae family (n=219), followed by Acrididae (n=23), Termitidae (n=17), Tortricidae (n=17), Tettigoniidae (n=15), Pentatomidae (n=16), Culicidae (n=14), while the other families detected were between 1 and 7 individuals. The obtained Shannon-Wiener index value was H’= 1.520 which indicated that the diversity level of insects at the observation site was at a moderate level.

Insect Population in Rice Ecosystems with Various Types of Irrigation and Local Rice Varieties

System of Rice Intensification is a new method of cultivation that has been widely done to improve the efficiency of water use, which can affect pest and predator populations. The research aims to determine the types of pests and natural enemies as predators in various irrigations and local varieties of rice. The study was conducted at the Research Field and Laboratory of Protection of the Faculty of Agriculture, University of Muhammadiyah Yogyakarta. The research was carried out with a 3x4 Strip Plot Design in a Completely Randomized Block Design with 3 replications. The factor I was the type of irrigation, consisting of 3 types of treatment, namely conventional irrigation, SRI intermittent irrigation for 10 days inundated 5 days dried, and irrigation for 7 days inundated, 3 days dry. Factor II was rice variety, which consists of 4 varieties, namely Rojolele Genjah, Mentik Wangi, Pandan Wangi, and Ciherang. Observation of pests and predators was done once a week for 5 weeks using the Sweeping Net trap. The numbers of pests and predators were analyzed by Generalized Linear Model analysis. The difference in the mean was further tested by the Tukey test. The results showed that the method of irrigation and varieties gave different effects depending on the role of the insect. Types of irrigation do not affect the population of pests, but irrigation affects the predator population. Varieties affect pest populations and predators. Irrigation types and varieties interact in determining pest populations and predators.

Developing traps for the overwintering tree-of-heaven weevils Eucryptorrhynchus scrobiculatus and E. brandti (Coleoptera: Curculionidae).

The tree-of-heaven root and trunk weevils, Eucryptorrhynchus scrobiculatus (TRW) and E. brandti (TTW) are important boring pests of Ailanthus altissima in China. Overwintering TRW and TTW adults can continue to damage A. altissima trees and reproduce after they emerge from the soil each year. There is a lack of studies regarding the development of control measures during the overwintering period. A polyethylene terephthalate bottle trap (PETBT) and corrugated paper box trap (CPBT) were evaluated for their ability to trap TRW and TTW adults descending from trees to overwinter in the soil in Wutongshu and Shabatou locations in Ningxia, China. Significantly more overwintering TRW adults were caught by the PETBT than the CPBT. There were no significant differences in the TTW captures in PETBT when compared to the CPBT. Both PETBT and CPBT have little effect on trapping overwintering TTW adults. Further trapping studies showed that PETBT treatments significantly reduced overwintering TRW numbers caught in population monitoring trap nets placed on the A. altissima tree trunks (an average annual reduction of 42% than the untreated trees). These results demonstrate that PETBT is effective for trapping overwintering TRW adults. PETBT could be recommended as an alternative for managing TRW in the framework of integrated pest management. © 2021 Society of Chemical Industry.

Development of fish-based indices of biological integrity for Minnesota lakes

Indices of biological integrity (IBIs) have been developed for a wide variety of locales and ecological systems to describe their biological condition. Due to variability in geophysical and chemical conditions, IBIs are often developed regionally and applied to similar ecological systems. Researchers in Minnesota previously developed a fish IBI (FIBI) for lakes; however, its application was limited to lakes 40–200 ha surface area and located in central Minnesota. The objectives of this study were to develop FIBIs and ecologically meaningful thresholds for application to a broader suite of Minnesota lakes with surface areas 40–4,050 ha. Fish communities in 419 lakes throughout Minnesota were sampled using gill nets, trap nets, backpack electrofishers, and beach seines between mid-June and early-September 2005–2013. Fish species were assigned to functional groups based on family, tolerance, primary feeding niche, special habitat use, and whether they were native to Minnesota. Lakes were classified into seven groups based on their geophysical and chemical attributes, and four groups were ultimately used in FIBI development. A suite of potential metrics was evaluated for each of the four FIBIs based on their relationships to measures of human-induced watershed and in-lake stressors and 8–15 were retained for each FIBI. Metrics that were retained were summed, and composite scores were scaled 0–100. Biological Condition Gradient (BCG) models were developed for each FIBI. The BCG models established thresholds for impairment and exceptional condition. The FIBIs and thresholds are being used to guide clean water planning, restoration, and protection efforts and to complement pollutant-based water quality sampling efforts in lakes during the Minnesota watershed assessment process.

Factors determining spawning run dynamics and current state of sockeye salmon &lt;i&gt;Oncorhynchus nerka&lt;/i&gt; resources in the Kamchatka River

Hydrological regime and morphodynamics of the outlet part of the Kamchatka River, dynamics of mixing zone, patterns of juvenile Pacific salmon distribution and migration in the coastal waters of Kamchatsky Gulf in the zone of operating trap nets were analyzed on the results of complex field works prowided in summer period in 2018–2019; fishing and specifics of sockeye salmon spawning run in the river was described. In the course of analyzing the entire complex of available long-term data, an assessment of the likely impact of some key factors on the dynamics of anadromous migration of sockeye salmon in the Kamchatka River was made; biological statistics of spawners and current state of reproduction of this stock was demonstrated. It is found, that natural environmental factors, neither abiotic nor biotic (including fish health as population internal factor), could not cause disturbance of sockeye salmon spawning run dynamics in the Kamchatka River in recent years. Smoller body size and physiological imperfection of the spawners before the anadromous migration due to effects of high number of pink salmon in recent years are suggested to be the most likely cause of spawning run delay in late sockeye salmon morph. Regime of commercial use of the stock and general increasing pressure on the spawning stock by coastal fisheries are demonstrated to be the strongest outer factors to affect modern state of the resources and sockeye salmon population structure in the Kamchatka River, causing permanent escapement deficiency on spawning grounds in the river basin (first of all in the late morph), and also infact lead to disballance between different subpopulation groups in the composition of the stock. Recommendations in order to provide recovery and sustainable level of the Kamchatka River sockeye salmon stock are given in the perspective of more efficient commercial use of the stock next several years; highlights for further researches are outlined.

Degree of Nematodes Worm Infection in Pelagic Fish Populations from the Romanian Black Sea waters

"Pelagic fish species can be affected by a series of infectious and parasitic diseases. The data used for this study are represented by the biological material collected between 2018 and 2019, from trap nets along the Romanian Black Sea waters. To establish the degree of parasitism, the following species of pelagic fish were studied: Sprattus spratus -sprat, Engraulis encrasicholus - anchovy and Trachurus mediterraneus- horse mackerel. Four species of endoparasites were identified, belonging to nematodes, as follows: Hysterothylacium aduncum, Contracaecum sp., Porrocaecumsp. and Anisakis sp. The parasites, especially found as larvae, more in free state and less trapped in the internal organs, infested the abdominal cavity, leading to degenerations, atrophies and reduction of the fish functions. The intensity of the parasitism infestation could be lethal, the size of the stocks being severely damaged. At the analysed fish species, the infestation degree was under 20 parasites per host, a low number of species recording the maximum value of 40 parasites per host. The parasites tend to accumulate with the increase of the fish's size, young stages being less affected. Key-Words: parasites, fish, nematodes, intensity, infestation degree "

Evaluation of Light Trap System in Monitoring of Rice Pests, Brown Planthopper (Nilaparvata lugens)

Brown Planthopper (Nilaparvata lugens) is a major rice pest insect in Malaysia. Series of the outbreak has been recorded in 1991, 1909, 2011, and 2015 which caused heavy yield losses. The light trap is now commonly used to monitor the pest population to predict the outbreak. The population sampling was conducted based on the crop stage at a specific sampling point and area. It has been done manually through field observations using netting, sweeping, board tapping, or survey patrol. Those methods are laborious and time-consuming. Malaysia Agriculture Research and Development Institute (MARDI) has developed an early warning system for brown planthopper monitoring consisting of modular light traps and a weather database to provide earlier forecasts and more effective outbreak prediction. However, there is not much information about how effective the light trap operated in the open field to draw and trap the insects. The light trap's efficiency depends on a few factors like the trap design, type of light source, duration, and sampling time; all affect the trap's effectiveness. A 30W Compact fluorescence light (CFL) has been selected and used to build four operated light traps and placed at the appropriate selected location. Sampling works were conducted twice a week for three hours per night throughout the planting season (15 weeks). Comparative statistical analysis was conducted to evaluate the effectiveness of the light trap compared to the aerial netting method. The results showed that the difference is statistically significant between light trap and aerial netting with a value of 0.0167 at p &lt;0.05. Therefore, brown planthopper population monitoring is more effectively done using the new design light trap.

Status and Decline Causes of Fish and Prawn Diversity and Catch Efficiency of Fishing Gears in Gorai River, Bangladesh

Gorai River is one of the important rivers in Bangladesh for rich aquatic biodiversity. The river is originated from the Ganges-Padma River system, a trans-boundary river between India and Bangladesh. Once the river was rich in fish biodiversity, but due to man-made and natural causes the availability of fish reduced drastically. A comprehensive analysis of fish diversity indices, gear efficiency, catch composition and decline causes of fish diversity in Gorai River, Bangladesh was accompanied. The data were collected monthly basis from January to December 2018 from four major fishing sites of the river. A total of 62 fish and 2 prawn species under 12 orders and 24 families were recorded. Cypriniformes was the leading order consisting 27% of the total catch. The overall values of Shannon-Weaver diversity (H'), Margalef’s richness (d) and Pielou’s evenness (J') indices were recorded as 1.478, 15.115 and 0.481, respectively. The highest and lowest CPUE were recorded from seine net (5.2±1.72 kg gear-1 haul-1) and hook & long lines (0.0135±0.0015 kg gear-1 haul-1), respectively whereas, highest and lowest gear efficiency were recorded from lift net (0.321±0.036 kg gear-1 person-1 hour-1) and fish trap (0.0005±0.0002 kg gear-1 person-1 hour-1), respectively. Alternatively, the highest fish catch were recorded on April (21228±464.38 kg) and lowest on August (3855±138.21 kg). The fishermen identified a few noteworthy dangers to fish diversity, which should be addressed properly to enhance the fish biodiversity of Gorai River.

New Records of Alcidodes karelinii (Boheman, 1844) (Coleoptera: Curculionidae) in Stavropol Region, Russia

The data on discoveries of an adventive species of weevil Alcidodes karelinii (Boheman, 1844) (Coleoptera: Curculionidae) in Stavropol Region are presented. A. karelinii is collected in July and August 2011, 2014, 2015 and 2020 on forbs in an abandoned arable land, at the edge of a sunflower field, in a robinium forest belt, in a weedy grasses of cultivated plots. The material is collected by methods of entomological net mowing and soil trap lines. The species occurs sporadically in the Region, and is few in number in its habitats. The new records supply the data on the distribution of A. karelinii in the Cis-Caucasus.

Game fish response to dredging of a eutrophic urban lake in Minnesota

Mundahl ND, Hoisington J. 2020. Game fish response to dredging of a eutrophic urban lake in Minnesota. Lake Reserv Manage. 37:170–185. We compared relative abundances, average weights, and growth rates of 6 game fish species before and after the 1999–2001 partial dredging of Lake Winona, a eutrophic, urban lake in Minnesota, to determine whether lake dredging sustainably changed fish population structure to the benefit of anglers. Relative catch rates (trap nets, gill nets, electrofishing) and growth rates were obtained from various fish population assessments and lake surveys conducted by the Minnesota Department of Natural Resources (MN DNR) from 1980 to 2016 for both Lake Winona and Lake Oscar, an ecologically similar lake that has not been dredged. Before-after control-impact (BACI) analyses revealed that compared to Lake Oscar, relative catch rates in Lake Winona after dredging declined significantly for bluegill (Lepomis macrochirus), black crappie (Pomoxis nigromaculatus), and northern pike (Esox lucius), and increased significantly for walleye (Sander vitreus) and largemouth bass (Micropterus salmoides). Average weights of yellow perch (Perca flavescens) and pike increased significantly after dredging. Only black crappie displayed improved growth after dredging. Largemouth bass catch rates for quality- and preferred-size fish increased in postdredging surveys. Although predredging data are lacking, population size structures and relative weights of bluegill, crappie, and bass post dredging were within ranges that meet MN DNR management objectives. Overall, dredging of Lake Winona was followed by improved quality and structure of game fish populations in this system, something that decades of previous biomanipulation and macrophyte management had not accomplished.

Length‐to‐weight and length‐to‐length ratios of six cavefish species from the Pearl River Basin, South China

Length-to-weight and length-to-length ratios were estimated for six cavefishes including Yunnanilus longibarbatus, Yunnanilus bailianensis, Yunnanilus jinxiensis, Oreonectes polystigmus, Paranemachilus pingguoensis, and Paranemachilus genilepis from the upper reaches of the Pearl River, Guangxi Province, China (between 106.26E, 23.14N and 111.42E, 24.85N). The fish were captured between May and October in 2018 and 2019 using trap nets (mesh size 7 mm) set in front of selected caves at 6:30–7:30 p.m. and were hauled out at 6:30–7:30 a.m. the next day. After removal, the fish were measured and weighed immediately to the nearest 0.1 cm and 0.1 g, respectively. The regression parameter r2 was between .95 and .98. The total length-to-standard length ratios were also calculated with r2 ≥ .98. This study should provide a useful reference for biological studies and biodiversity conservation of cavefish.

Urbanisation is a main driver for Aedes aegypti dynamics and arboviral risk in Côte d’Ivoire

Abstract Background Aedes mosquito-borne arboviruses have (re-)emerged and caused considerable public health concerns in major sub-Saharan African cities subjected to rapid urbanisation. We assessed the effects of urbanisation on Aedes aegypti dynamics and biting pattern, and the risk of transmission of yellow fever (YF) and dengue (DEN) viruses along urban-rural gradient in Côte d'Ivoire. Methods We collected Aedes mosquitoes as eggs, larvae/pupae, and adults seasonally in urban, suburban and rural areas using ovitrap, larval survey and human-baited double net trap methods from January 2015 to December 2016. We sampled household data and characterised Aedes larval breeding sites. Ae. aegypti indices and biting rates were compared by area. Results Ae. aegypti was the most abundant species in all areas. It showed higher abundance in urban areas (n = 26,072; 99.4%). Larval indices were associated with human activities, including waste and water management. Tires and discarded containers were the most productive breeding sites in all areas. Household water receptacles displayed high Aedes-positive rate (23.6%) in urban areas. Positive ovitrap index was higher in urban (53.5%) compared to suburban (43.1%) and rural (29.7%). Stegomyia indices were highest in urban followed by suburban and rural areas, with respective house index of 67.2, 51.4 and 27.8, container index of 57.1, 43.5 and 19.7, and Breteau index of 95.2, 78.9 and 8.8. Biting rate was 4.3 and 2.7-fold higher in urban (83.5 bite/person/day) and suburban (52.1 bite/person/day) compared to rural (19.4 bite/person/day), respectively. Ae. aegypti indices were higher during rainy seasons. Conclusions In Côte d'Ivoire, urbanisation raised Ae. aegypti abundance and biting rate. As a result, YF and DEN risk indices were above WHO-established epidemic thresholds in urban area thus exposing local communities to high risk of getting diseases. Integrated community-based vector control programs should be applied to reduce arboviral risk. Key messages Urbanisation raises Aedes aegypti abundance and arboviral disease risk in Côte d’Ivoire. Integrated community clean-up actions are required to control Aedes vectors.