Research Articles (Zoology and Entomology)

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A collection containing some of the full text peer-reviewed/ refereed articles published by researchers from
the Department of Zoology and Entomology

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Southern Ocean food-webs and climate change : a short review and future directions
(Public Library of Science, 2024-03-11) Queiros, Jose P.; Borras-Chavez, Renato; Friscourt, Noemie; Groß, Jasmin; Lewis, Candice B.; Mergard, Georgia; O’Brien, Katie
Food-webs are a critical feature of ecosystems and help us understand how communities will respond to climate change. The Southern Ocean is facing rapid and accelerating changes due to climate change. Though having evolved in an isolated and somewhat extreme environment, Southern Ocean biodiversity and food-webs are among the most vulnerable. Here, we review 1) current knowledge on Southern Ocean food-webs; 2) methods to study foodwebs; 3) assessment of current and future impacts of climate change on Southern Ocean food-webs; 4) knowledge gaps; and 5) the role of Early Career Researchers (ECRs) in future studies. Most knowledge on Southern Ocean food-webs come from the pelagic environment, both at macro- and microbial levels. Modelling and diet studies of individual species are major contributors to the food-web knowledge. These studies revealed a short food-web, predominantly sustained by Antarctic Krill (Euphausia superba). Additionally, alternative pathways exist, involving other krill species, fish, and squid, which play equally important roles in connecting primary producers with top predators. Advantages and disadvantages of several techniques used to study Southern Ocean food-webs were identified, from the classical analyses of stomach contents, scats, or boluses to the most recent approaches such as metabarcoding and trophic-biomarkers. Observations show that climate change can impact the foodweb in different ways. As an example, changes to smaller phytoplankton species can lengthen the food-web, increasing assimilation losses and/or changing nutrient cycles. Future studies need to focus on the benthic-dominated food-webs and the benthopelagic coupling. Furthermore, research during the winter season and below the ice-shelves is needed as these areas may play a crucial role in the functioning of this ecosystem. ECRs can play a significant role in advancing the study of Southern Ocean food-webs due to their willingness for interdisciplinary collaboration and proficiency in employing various methodologies, contributing to the construction of high-resolution food-webs.
Transgenerational cross-susceptibility to heat stress following cold and desiccation acclimation in the angoumois grain moth
(Wiley, 2024-12) Mpofu, Precious; Machekano, Honest; Airs, Paul M.; Nyamukondiwa, Casper
The Angoumois grain moth, Sitotroga cerealella (Olivier), is a significant cosmopolitan primary pest of cereals worldwide and has thrived in divergent environments. However, the mechanisms underlying its survival in multiple contrasting environments are poorly understood. Here, we hypothesised that when facing diverse environmental stress, F1 generation exhibits transgenerational cross-protection as a mechanism to persist under divergent stressful environments. Notably, F1 acclimation to cold or desiccation conditions could either enhance or lower heat tolerance in the F2 generation. Specifically, we tested whether typical diurnal fluctuations and/or winter rapid or chronic cold temperatures (18–22 C) as well as desiccation acclimation of F1 parental population yields transgenerational cross-protection/susceptibility to heat stress on F2 offspring. F1 moths were exposed to cold hardening (2 h), chronic (72 h) and variable (fluctuating between 18 and 22 C for 72 h) temperature treatment groups. Desiccation treatment included incubation at 0%–1% relative humidity (24 h). F2 generation moths were then assessed for heat tolerance using critical thermal maxima (CTmax) at three different ramping rates (0.06, 0.25 and 0.5 C/min) as well as heat knockdown time (HKDT). Findings indicated that (i) desiccation, cold hardening and chronic low-temperature acclimations in F1 reduced heat tolerance in F2 populations and (ii) ramping rate was crucial to decipher differences between treatment groups, with lower ramping rates associated with lower CTmax. Transgenerational cross-susceptibility to heat stress indicates possible fitness costs of exposure to multiple contrasting stressors in the Angoumois grain moth and can be used in designing physical pest management strategies.
Successful alien plant species exhibit functional dissimilarity from natives under varied climatic conditions but not under increased nutrient availability
(Wiley, 2025-03) Milanovic, Marija; Bakker, Jonathan D.; Biederman, Lori; Borer, Elizabeth; Catford, Jane A.; Cleland, Elsa; Hagenah, Nicole; Haider, Sylvia; Harpole, W. Stanley; Komatsu, Kimberly; Macdougall, Andrew S.; Roemermann, Christine; Seabloom, Eric W.; Knapp, Sonja; Kuehn, Ingolf
AIMS : The community composition of native and alien plant species is influenced by the environment (e.g., nutrient addition and changes in temperature or precipitation). A key objective of our study is to understand how differences in the traits of alien and native species vary across diverse environmental conditions. For example, the study examines how changes in nutrient availability affect community composition and functional traits, such as specific leaf area and plant height. Additionally, it seeks to assess the vulnerability of high-nutrient environments, such as grasslands, to alien species colonization and the potential for alien species to surpass natives in abundance. Finally, the study explores how climatic factors, including temperature and precipitation, modulate the relationship between traits and environmental conditions, shaping species success. LOCATION : In our study, we used data from a globally distributed experiment manipulating nutrient supplies in grasslands worldwide (NutNet). METHODS : We investigate how temporal shifts in the abundance of native and alien species are influenced by species-specific functional traits, including specific leaf area (SLA) and leaf nutrient concentrations, as well as by environmental conditions such as climate and nutrient treatments, across 17 study sites. Mixed-effects models were used to assess these relationships. RESULTS : Alien and native species increasing in their abundance did not differ in their leaf traits. We found significantly lower specific leaf area (SLA) with an increase in mean annual temperature and lower leaf Potassium with mean annual precipitation. For trait–environment relationships, when compared to native species, successful aliens exhibited an increase in leaf Phosphorus and a decrease in leaf Potassium with an increase in mean annual precipitation. Finally, aliens' SLA decreased in plots with higher mean annual temperatures. CONCLUSIONS: Therefore, studying the relationship between environment and functional traits may portray grasslands' dynamics better than focusing exclusively on traits of successful species, per se.
Temporal dynamics of scout release-behavior of termitophagous ponerine ant, Megaponera analis
(Springer, 2024-11-05) Modiba, Rifilwe V.; Pirk, Christian Walter Werner; Yusuf, Abdullahi Ahmed
Megaponera analis is an obligate termitophagous species endemic to sub-Saharan Africa. The species forages by sending out scouts to search for termites. Once termites are located, the scouts return to the nest and recruit nest mates. Scouts face unpredictable environmental conditions, including sudden flooding, temperature changes, high winds and predation by natural enemies. We observed 519 scouting trips from 18 different colonies over three years to determine how long it takes for the colony to replace a scout that has likely died while on scouting duty or is lost due to environmental perturbations. Study areas were at Maremani, Musina, Masebe and D’nyala Nature Reserves in the Limpopo Province of South Africa. We introduced definitions of scouting turnover, scouting trip, and scouting session. Scouting turnover is the time it takes a successive scout to leave the nest for a trip, whereas a scouting trip is the journey a scout takes from the nest in search of food. Since M. analis shows bimodal foraging behavior, the morning observations were recorded as the first scouting session, while the subsequent session, which starts in the afternoon, was recorded as the second scouting session. The mean scouting turnover for all 519 trips was 9.36 ± 0.64 (SD) minutes. When turnover was divided into sessions, the first scouting session lasted a mean of 7.77 ± 12.17 (SD) minutes, while the second had 10.34 ± 18.32 (SD) minutes. The minimum turnover was zero minutes, and the maximum was 124 minutes.
The effects of diet and semiochemical exposure on male Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) metabolic rate at a range of temperatures
(Elsevier, 2024-12) Dacre, Dylan Christopher; Duncan, Frances D.; Weldon, Christopher William; cwweldon@zoology.up.ac.za
The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is an invasive species that has rapidly spread across the African continent, endangering the security of agricultural industries. The sterile insect technique (SIT) is being investigated as a viable additional pest management tool to suppress B. dorsalis populations after its successful implementation in other parts of the world. There is evidence to suggest that pre-release nutritional and semiochemical treatments for sterilised males can enhance their competitive performance against wild type males in SIT programs. This study examined how sterilisation, a diet rich in protein (addition of yeast hydrolysate) or containing semiochemicals (methyl eugenol or eugenol) affected the resting metabolic (RMR) of male B. dorsalis at different temperatures (15 – 30 ◦C), measured using flow-through respirometry. Our results indicated that the negative effect of sterilisation on RMR decreased as temperature increased and that duration of exposure to semiochemicals for 1 to 4 days was not a significant influencing factor on male B. dorsalis RMR. Protein-rich diet increased average RMR, but the difference in RMR between dietary groups decreased as temperature increased. Semiochemical feeding reduced the average RMR in male B. dorsalis. The difference in RMR between males that consumed semiochemical and those that did not increased with as temperature increased.
From parachuting to partnership : fostering collaborative research in protected areas
(Wiley, 2025-01) Smit, Izak P.J.; Fernández, R.J.; Menvielle, M.F.; Roux, D.J.; Singh, N.; Mabuza, S.; Mthombeni, B.M.; Macgregor, N.A.; Fritz, H.; Gandiwa, E.; Foxcroft, L.C.; Cook, C.N.
Research in protected areas (PAs) is often dominated by scientists from outside the conservation agencies managing them. This can potentially lead to misalignment with local needs, insensitivity to the local context and a lack of investment in and use of local expertise. These issues often arise when international researchers work in another country without local engagement (known as ‘parachute science’). Despite PAs being key end users of actionable science, there is limited understanding of the prevalence and impact of parachute science in these areas. Here, we investigate parachute versus collaborative research in two national parks in the Global South (Kruger National Park, South Africa; Nahuel Huapi National Park, Argentina) and one park from a developed economy (Kakadu National Park, Australia). To explore the prevalence, risks, benefits and complexities of research practices, we analyse the patterns of authorship, funding and acknowledgement in a random sample of peer-reviewed papers from research conducted in these parks. Our findings show a higher incidence of potential parachute science in Kruger National Park (18% of papers with only out-of-country authors) compared to Nahuel Huapi (4%) and Kakadu (2%) national parks. However, the occurrence of internationally collaborative research (national and international authors) was double in Global South parks (35%–38%) than in the Australian park (18%). The study illustrates the potential benefits of international collaboration for PAs, including increased research productivity, expanded funding sources and possibly higher impact and visibility of published studies. PAs in developed countries may have fewer opportunities to obtain those benefits. Most papers, even those with in-country authors, lacked authors affiliated with the agency managing the PA and often failed to even acknowledge these agencies. This suggests the potential for a different form of parachute science (which we term ‘park parachuting’) in which lack of local involvement may hamper integration of research with management. SYNTHESIS AND APPLICATIONS : Establishing conditions that foster collaboration between national and international researchers, and between PA agency staff and external researchers (regardless of their nationality), would enable parks to better serve as catalysts for research collaboration. This collaborative approach can facilitate access to additional funding, enhance research capacity, increase research productivity and amplify research impact.
Using indicators to assess the status of biological invasions and their management on islands─the Prince Edward Islands, South Africa as an example
(Springer, 2025-03) Fernandez Winzer, Laura; Greve, Michelle; Le Roux, Peter Christiaan; Faulkner, Katelyn T.; Wilson, John R.U.
Addressing the challenge biological invasions pose to island biodiversity is pivotal to achieving Target 6 of the Kunming–Montreal Global Biodiversity Framework. Using a suite of 24 indicators, we evaluated the current status of biological invasions and their management on the Prince Edward Islands, South Africa’s sub-Antarctic territories, and provide recommendations for management. There are 45 established alien taxa on Marion Island, of which 25 are invasive, and nine invasive taxa on the less frequently visited Prince Edward Island. However, despite stringent biosecurity, new alien taxa continue to arrive, potentially through ten introduction pathways, but particularly as contaminants on goods and stowaways on transport vectors. Not all detected taxa have been systematically recorded or identified—identifying incursions to species level may help pinpoint gaps in biosecurity. Three invasive plant species have caused Major environmental impacts (as per the Environmental Impact Classification for Alien Taxa categories), and Massive impacts have been recorded for the house mouse. An ambitious plan to eradicate the house mouse is being developed. A further eight taxa are controlled and four monitored to determine whether they have been eradicated. We argue that systematically tracking and documenting biological invasions is vital to improve the appropriateness, adaptability, and responsiveness of management; and we recommend a dedicated, integrated reporting process involving all stakeholders. Such monitoring is particularly important for remote sites given competing demands to reduce the human footprint, manage biological invasions, and allow access. This article is part of the theme issue ‘Managing biological invasions in protected areas: moving towards the new Global Biodiversity Framework targets’.
Sleep in the East African root rat, Tachyoryctes splendens
(Wiley, 2024-12) Kruger, Jean‐Leigh; Bhagwandin, Adhil; Katandukila, Jestina V.; Bennett, Nigel C.; Manger, Paul R.
The present study reports the results of an electrophysiological analysis of sleep in the East African root rat, Tachyoryctes splendens, belonging to the rodent subfamily Spalacinae. Telemetric electroencephalographic (EEG) and electromyographic recordings, with associated video recording, on three root rats over a continuous 72 h period (12 h light/12 h dark cycle) were analyzed. The analysis revealed that the East African root rat has a total sleep time (TST) of 8.9 h per day. Despite this relatively short total sleep time in comparison to fossorial rodents, nonrapid eye movement (non‐REM) sleep and rapid eye movement (REM) sleep states showed similar physiological signatures to that observed in other rodents and no unusual sleep states were observed. REM occupied 19.7% of TST, which is within the range observed in other rodents. The root rats were extremely active during the dark period, and appeared to spend much of the light period in quiet wake while maintaining vigilance (as determined from both EEG recordings and behavioral observation). These recordings were made under normocapnic environmental conditions, which contrasts with the hypercapnic environment of their natural burrows.
Expression of honey bee (Apis mellifera) sterol homeostasis genes in food jelly producing glands of workers
(Wiley, 2024-06) Yusuf, Abdullahi Ahmed; Pirk, Christian Walter Werner; Buttstedt, Anja
Adult workers of Western honey bees (Apis mellifera L.) acquire sterols from their pollen diet. These food sterols are transported by the hemolymph to peripheral tissues such as the mandibular and the hypopharyngeal glands in the worker bees' heads that secrete food jelly which is fed to developing larvae. As sterols are obligatory components of biological membranes and essential precursors for molting hormone synthesis in insects, they are indispensable to normal larval development. Thus, the study of sterol delivery to larvae is important for a full understanding of honey bee larval nutrition and development. Whereas hypopharyngeal glands only require sterols for their membrane integrity, mandibular glands add sterols, primarily 24‐methylenecholesterol, to its secretion. For this, sterols must be transported through the glandular epithelial cells. We have analyzed for the first time in A. mellifera the expression of genes which are involved in intracellular movement of sterols. Mandibular and hypopharyngeal glands were dissected from newly emerged bees, 6‐day‐old nurse bees that feed larvae and 26‐day‐old forager bees. The expression of seven genes involved in intracellular sterol metabolism was measured with quantitative real‐time PCR. Relative transcript abundance of sterol metabolism genes was significantly influenced by the age of workers and specific genes but not by gland type. Newly emerged bees had significantly more transcripts for six out of seven genes than older bees indicating that the bulk of the proteins needed for sterol metabolism are produced directly after emergence.
Light sensitivity of the circadian system in the social highveld mole-rat Cryptomys hottentotus pretoriae
(Company of Biologists, 2024-09) Chanel, Pauline N.C.; Bennett, Nigel C.; Oosthuizen, Maria Kathleen
Highveld mole-rats (Cryptomys hottentotus pretoriae) are social rodents that inhabit networks of subterranean tunnels. In their natural environment, they are rarely exposed to light, and consequently their visual systems have regressed over evolutionary time. However, in the laboratory they display nocturnal activity, suggesting that they are sensitive to changes in ambient illumination. We examined the robustness of the Highveld mole-rat circadian system by assessing its locomotor activity under decreasing light intensities. Mole-rats were subjected to seven consecutive light cycles commencing with a control cycle (overhead fluorescent lighting at 150 lx), followed by decreasing LED lighting (500, 300, 100, 10 and 1 lx) on a 12 h light:12 h dark (L:D) photoperiod and finally a constant darkness (DD) cycle. Mole-rats displayed nocturnal activity under the whole range of experimental lighting conditions, with a distinct spike in activity at the end of the dark phase in all cycles. The mole-rats were least active during the control cycle under fluorescent light, locomotor activity increased steadily with decreasing LED light intensities, and the highest activity was exhibited when the light was completely removed. In constant darkness, mole-rats displayed free-running rhythms with periods (τ) ranging from 23.77 to 24.38 h, but was overall very close to 24 h at 24.07 h. Our findings confirm that the Highveld mole-rat has a higher threshold for light compared with aboveground dwelling rodents, which is congruent with previous neurological findings, and has implications for behavioural rhythms.
Evolutionary shifts in the thermal biology of a subterranean mammal : the effect of habitat aridity
(Company of Biologists, 2024-12) Merchant, Hana N.; Hart, Daniel William; Bennett, Nigel C.; Janse van Vuuren, Andries Koch; Freeman, Marc Trevor; McKechnie, Andrew E.; Faulkes, Chris G.; Mordaunt, Nathan D.; Portugal, Steven J.
Subterranean mammals representing a single subspecies occurring along an aridity gradient provide an appropriate model for investigating adaptive variation in thermal physiology with varying levels of precipitation and air temperature. This study examined the thermal physiological adaptations of common mole-rats (Cryptomys hottentotus hottentotus) across five populations along an aridity gradient, challenging the expectation that increased aridity would lead to reduced metabolic rate, lower body temperatures and broader thermoneutral zones. No significant, consistent differences in metabolic rate, body temperature or thermal conductance were observed between populations, suggesting uniform thermoregulatory mechanisms across habitats. Instead, behavioural strategies such as huddling and torpor may play a more prominent role than physiological adaptations in managing temperature regulation and water balance. The study also observed osmoregulatory differences, with populations employing distinct behavioural cooling strategies in response to water availability. These results underscore the need for further research into the responses of subterranean species to climate change, particularly in understanding how increasing global temperatures and aridification might influence species distribution if they lack the physiological capacity to adapt to future climatic conditions.
Contest competition and injury in adult male sub-Antarctic fur seals
(Springer, 2024-05) Bester, Marthan Nieuwoudt; Rossouw, G.J.; Van Staden, Paul Jacobus; mnbester@zoology.up.ac.za
We recorded intra-sexual behaviour of adult male sub-Antarctic fur seals Arctocephalus tropicalis at Gough Island, Southern Ocean, during the 1975/76 summer breeding season. Our re-analysed data address male ‘contest competition’, which relates to the costs of intra-sexual disputes, including fights. We considered the risks/benefits of fighting through investigation of injuries (n = 353) sustained by adult males (n = 124) in fights. Injuries were predominantly on the forequarters, especially around the insertion areas of the front flippers (41%) with its sparse pelage, compared to the neck and chest areas combined (29%), an area which is well protected by thick pelage. The infliction of serious, sometimes debilitating, injuries to competitors increases a male’s access to females. Injuries predominate in injured, defeated males that gather at non-breeding sites, suggesting that injuries inflicted by dominant males were successful in excluding competing males from breeding sites.
Use of acoustic signals in Cape fur seal mother–pup reunions : individual signature, signal propagation and pup home range
(Company of Biologists, 2024-07) Martin, Mathilde; Gridley, Tess; Immerz, Antonia; Elwen, Simon H.; Charrier, Isabelle
The Cape fur seal (Arctocephalus pusillus pusillus) is one of the most colonial mammals, with colonies of up to hundreds of thousands of individuals during the breeding season. During the lactation period, mothers and pups are regularly separated as females undertake multiday foraging trips at sea. Mothers and pups use a mutual vocal recognition system to reunite after separation. Such communication is highly constrained by both high background noise and risk of individual confusion owing to the density of seals. This study aimed to experimentally assess the acoustic features relevant for mother–pup vocal identification and the propagation properties of their calls. Playback experiments revealed that mother and pup individual vocal signatures rely on both temporal and frequency parameters: amplitude and frequencymodulations, timbre and fundamental frequency (f0). This is more parameters than in any colonial species studied so far. The combinational use of acoustic features reinforces the concept that both environmental and social constraints may have acted as selective pressures on the individual vocal recognition systems. Theoretical propagation distances of mother and pup vocalisations were estimated to be below the range of distances at which mother–pup reunions can occur. This suggests that Cape fur seals may have strong abilities to extract vocal signals from the background noise, as previously demonstrated in the highly colonial king penguin. Investigating the transmission of information throughout the propagation of the signal as well as the ability of the receiving individual to decipher vocal signatures is crucial to understanding vocal recognition systems in the wild.
A mouse in the spotlight : response capacity to artificial light at night in a rodent pest species, the southern multimammate mouse (Mastomys coucha)
(Elsevier, 2024-12) Oosthuizen, Tasha; Pillay, Neville; Oosthuizen, Maria Kathleen; moosthuizen@zoology.up.ac.za
Multimammate mice are prolific breeders, can cause significant agricultural damage, and are reservoir hosts for a number of pathogens. They are nocturnal and given their success in urbanised rural environments, we were interested in how they would respond to increasingly bright anthropogenic spaces. We evaluated the locomotor activity of southern multimammate mice (Mastomys coucha), under four treatments: in an outdoor enclosure with natural light and temperature fluctuations, in a laboratory under a standard light regime, and two artificial light at night (ALAN) regimes (2 Lux) of varying proximity. The study animals remained nocturnal for the duration of the experiments. They were more active under the laboratory conditions with lower day-time light levels compared to the outdoor treatment but reduced their activity under ALAN. When the night light originated remotely, activity levels decreased by more than 50%, whereas under direct ALAN from above the cages, there was a 75% decrease in activity. The onset of activity was later during the two LAN treatments. We concluded that Mastomys coucha is strongly averse to light and show severe behavioural and circadian responses to light at night. We predict that it is unlikely that Mastomys will flourish in cities, but that they could thrive in and around dark urbanised refugia.
Orientation, thermal characteristics and structural dimensions of Mangrove Kingfisher Halcyon senegaloides nest cavities in arboreal termitaria in central Mozambique
(Taylor and Francis, 2024) Pietersen, Darren William; Davies, Gregory B.P.; Symes, Craig Thomas
The breeding ecology of the Mangrove Kingfisher Halcyon senegaloides (family Alcedinidae) remains poorly known. While the few nests recorded in southern and East Africa have been in tree hollows, a seasonal population in central Mozambique woodland breeds in cavities in arboreal termitaria. Despite this breeding strategy being widely recorded in many tropical kingfisher species, it has received little research attention in the Afrotropical realm. We report on the siting and structural characteristics of arboreal termitaria used as nesting sites by Mangrove Kingfishers in central Mozambique and document the thermal dynamics of a nesting cavity in an arboreal termitarium. Arboreal termitaria (average volume 40.1 ± 23.8 l) occurred at a density of 0.52 ± 0.22 termitaria ha–1 in large trees or shrubs, mostly of the families Fabaceae and Malvaceae. Termitaria containing nest cavities were situated 10.8 ± 3.1 m above the ground, and most nests (78.6%) faced north. Nest cavity temperatures averaged 31.4 ± 2.6 °C, which is warmer and more stable than the average ambient temperatures of 28.7 ± 4.0 °C. ‘Carton’ termitaria (comprising a mixture of faecal matter and wood fragments) are thus believed to confer a thermal advantage for summer-nesting Mangrove Kingfishers.
Polyandry contributes to Gonipterus platensis (Coleoptera: Curculionidae) rearing
(PeerJ Inc., 2024-08) Ribeiro, Murilo F.; Cavallini, Gabriela; Solce, Gabriel N.; Favoreto, Ana L.; De Souza Passos, José R.; Hurley, Brett Phillip; Wilcken, C.F.
BACKGROUND: Gonipterus platensis Marelli, 1926 (Coleoptera: Curculionidae) is one of the main defoliating beetles in Eucalyptus plantations. Biological control with egg parasitoids is one of the main control strategies for this pest and a constant supply of fresh host eggs is required to rear the parasitoids. Polyandry can influence Gonipterus oviposition by increasing female fecundity and fertility; however, the high density of individuals in laboratory colonies can lead to male harassment, resulting in lower reproduction rate. The aim of this study was to measure the effects of monoandry and polyandry on the reproduction of G. platensis and the effects of male harassment on laboratory rearing conditions. METHODS: Reproductive parameters were compared between three treatments: monoandry, where the female was allowed to mate daily with the same male; no choice polyandry, where the female was allowed to mate daily with a different male; and polyandry with choice, where the female was allowed to mate daily, but with a choice between five different males. Another experiment varying the density of males was conducted to evaluate the effect of male harassment. RESULTS: Polyandry with choice resulted in the longest period of oviposition, highest fecundity and highest number of eggs per egg capsules when compared to monoandrous females. No negative effect related to male harassment in the laboratory, such as decreased fertility, fecundity, or number of eggs per egg capsule, was detected. CONCLUSION: Polyandry contributes to mass rearing as it increases fecundity and oviposition period on females and there is no evidence of male harassment on G. platensis.
Conservation gaps and priorities of range-restricted birds in the Northern Andes
(PeerJ Inc., 2024-02) Medina, Wilderson; Pimm, Stuart L.; Huang, Ryan
The ongoing destruction of habitats in the tropics accelerates the current rate of species extinction. Range-restricted species are exceptionally vulnerable, yet we have insufficient knowledge about their protection. Species’ current distributions, range sizes, and protection gaps are crucial to determining conservation priorities. Here, we identified priority range-restricted bird species and their conservation hotspots in the Northern Andes. We employed maps of the Area of Habitat (AOH), that better reflect their current distributions than existing maps. AOH provides unprecedented resolution and maps a species in the detail essential for practical conservation actions. We estimated protection within each species’ AOH and for the cumulative distribution of all 335 forest-dependent range-restricted birds across the Northern Andes. For the latter, we also calculated protection across the elevational gradient. We estimated how much additional protection community lands (Indigenous and Afro-Latin American lands) would contribute if they were conservation-focused. AOHs ranged from 8 to 141,000 km2 . We identified four conservation priorities based on cumulative species richness: the number of AOHs stacked per unit area. These priorities are high-resolution mapped representations of Endemic Bird Areas for the Tropical Andes that we consider critically important. Protected areas cover only 31% of the cumulative AOH, but community lands could add 19% more protection. Sixty-two per cent of the 335 species have ranges smaller than their published estimates, yet IUCN designates only 23% of these as Threatened. We identified 50 species as top conservation priorities. Most of these concentrate in areas of low protection near community lands and at middle elevations where, on average, only 34% of the land is protected. We highlight the importance of collaborative efforts among stakeholders: governments should support private and community-based conservation practices to protect the region with the most range-restricted birds worldwide.
A frog in hot water : the effect of temperature elevation on the adrenal stress response of an African amphibian
(PeerJ Inc., 2024-08) Scheun, Juan; Venter, Leanne; Ganswindt, Andre
Amphibians, with their unique physiology and habitat requirements, are especially vulnerable to changes in environmental temperatures. While the activation of the physiological stress response can help to mitigate the impact of such habitat alteration, chronic production of elevated glucocorticoid levels can be deleterious in nature. There is no empirical evidence indicating the physiological response of African amphibians to temperature changes, where individuals are unable to emigrate away from potential stressors. To rectify this, we used the edible bullfrog (Pyxicephalus edulis) as a model species to determine the effect of elevated temperature on the adrenocortical response of the species using a recently established matrix. While a control group was kept at a constant temperature (25 ◦C) throughout the study period, an experimental group was exposed to control (25 ◦C) and elevated temperatures (30 ◦C). Mucous swabs were collected throughout the study period to determine dermal glucocorticoid (dGC) concentrations, as a proxy for physiological stress. In addition to this, individual body mass measurements were collected. The results showed that individuals within the experimental group who experienced increased temperatures had significantly elevated dGC levels compared to the control animals. Furthermore, there was a significant difference in the percentage mass change between experimental and control animals . These findings indicate the physiological sensitivity of the edible bullfrog to a thermal stressor in captivity. While this study shows the importance of proper amphibian management within the captive environment, it also highlights the coming danger of global climate change to this and similar amphibian species.
Only incandescent light significantly decreases feeding of Anopheles funestus s.s. (Diptera: Culicidae) mosquitoes under laboratory conditions
(Springer, 2024-10) Van Zyl, Layla; Burke, Ashley M.; Koekemoer, Lizette L.; Coetzee, Bernard Walter Thomas; bernard.coetzee@up.ac.za
Recent work has demonstrated that exposure to artificial light at night (ALAN) may alter mosquito feeding behavior and so must be considered a moderator of vector-borne disease transfer. Anopheles funestus mosquitoes are a primary malaria vector in sub-Saharan Africa, but no study to date has tested the impact of ALAN on their feeding behavior. Here we test if the exposure to commonly used household lights (compact fuorescent lights, light-emitting diodes, and incandescent lights) alters Anopheles funestus feeding. Mated, unfed female mosquitoes were exposed to a light treatment, at the onset of darkness, followed by a blood-feeding assay. The light treatments consisted of a 30-min light pulse of one of the three household lights, each in individual experimental containers, versus controls. All three household lights resulted in a reduction in the percentage of females taking a blood meal, but only mosquitoes exposed to incandescent light showed a statistically significant reduction in feeding of 19.6% relative to controls which showed a 42.8% feeding rate. Our results suggest that exposure to some household lights during the night may have an immediate inhibitory effect on Anopheles funestus feeding. By helping identify which light types lead to a suppression of feeding, the findings of this study could provide insight necessary to design household lights that can help minimize mosquito feeding on humans.
Feeding habits and malaria parasite infection of Anopheles mosquitoes in selected agroecological areas of Northwestern Ethiopia
(BMC, 2024-10) Belay, Aklilu; Asale, Abebe; Sole, Catherine L.; Yusuf, Abdullahi A.; Torto, Baldwyn; Mutero, Clifford Maina; Tchouassi, David Poumo
BACKGROUND: Surveillance of the host–anopheline mosquitoes’ interaction is important for assessing malaria transmission risk and guiding vector control. We assume that changes in malaria vector species’ feeding habits, as well as the surrounding environment, have a substantial impact on varied malaria transmission. In this study, we determined the vertebrate host feeding patterns of anopheline mosquitoes to characterize entomologic risk factors for malaria in Jabi Tehnan, Northwestern Ethiopia. METHODS: Blood-fed anophelines surveyed during malaria surveillance in Jabi Tehnan district of northwestern Ethiopia were utilized in this study. They were collected using Centers for Disease Control and Prevention (CDC) light traps deployed in selected households per village, placed indoors and outdoors, spanning three agroecological settings (dry mountain, plateau, and semiarid highlands) between June 2020 and May 2021. The engorged mosquitoes were analyzed for host blood meal sources and Plasmodium infection via polymerase chain reaction (PCR) and/or sequencing. Infection rates and bovine and human blood indices were calculated and compared for abundant species; between indoors and outdoors and between agroecology using a chi-squared test for equality of proportion in R package at a significant level of p≤0.05. RESULTS: A total of 246 mosquitoes were successfully typed (indoor, 121; outdoor, 125), with greater relative abundance indoors in mountain and plateau highlands, and outdoors in semiarid areas. Despite ecological differences in blood-fed capture rates, cattle served as the most utilized blood meal source by 11 anopheline species with an overall bovine blood index (BBI) of 74.4%. This trend was dictated by Anopheles gambiae s.l. (198/246; BBI=73.7%), which exhibited the most plastic feeding habits that included humans (human blood index=15.7%) and other livestock and rodents. A total of fve anopheline species (An. gambiae s.l., An. funestus s.l., An. coustani s.l., An. pretoriensis, and An. pharoensis) fed on humans, of which the first three were found infected with Plasmodium parasites. Most of the infected specimens were An. arabiensis (5.6%, 11/198) and had recently fed mainly on cattle (72.7%, 8/11); one each of infected An. funestus s.l. and An. coustani s.l. had fed on humans and cattle, respectively. CONCLUSIONS: The results demonstrate communal feeding on cattle by anophelines including primary and secondary malaria vectors. This study also indicates the importance of cattle-targeted interventions for sustainable control of malaria vectors in the study areas.

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