Ability Of Predators Research Articles

Predation capacity of Bradymonabacteria, a recently discovered group in the order Bradymonadales, isolated from marine sediments.

Bacterial predation is a vital feeding behavior that affects community structure and maintains biodiversity. However, predatory bacterial species in coastal sediments are comparatively poorly described. In this study, the predation capacity of all nine culturable Bradymonabacteria strains belonging to the recently discovered order Bradymonadales was determined against different types of prey. The predatory efficiency of Bradymonabacteria increased as the initial prey proportion in a mixed culture decreased. When the initial prey proportion was 0.5, the number of surviving prey bacterial cells significantly decreased after 4h of predation with the Bradymonabacteria strains TMQ1, SEH01, B210 and FA350. However, growth of the prey strain occurred in the presence of the Bradymonabacteria strains TMQ4, TMQ2, TMQ3, V1718 and YN101. When the initial prey proportion decreased to 0.1 or 0.01, most of the Bradymonabacteria strains preyed efficiently. Furthermore, established neighboring colonies of prey were destroyed by Bradymonabacteria. This invading predation capacity was determined by the predation ability of the strain and its motility on the agar surface. Our findings provide new insights into the potential ecological significance of predatory Bradymonabacteria, which may serve as a potential probiotic for use in the aquaculture.

Age-Stage, Two-Sex Life Table and Functional Response of Amblyseius orientalis (Acari: Phytoseiidae) Feeding on Different Nutrient Sources.

Amblyseius orientalis Ehara is a predatory mite that belongs to the family Phytoseiidae. It is mainly found in Jiangxi, Shanghai, Guangdong, and other areas of China. Although A. orientalis is a dominant predatory mite species in China and is also important for agriculture and biological control, not many studies have investigated it. Thus, research on A. orientalis is necessary. However, its application in biological control is hindered by the absence of techniques for the mass rearing of A. orientalis in captivity. We conducted experiments to determine the growth, development, reproduction, and functional response of A. orientalis in this study by indoor single-head rearing at 25 ± 1 °C, 65 ± 5% relative humidity, and a photoperiod of a 16 h:8 h light/dark cycle under laboratory conditions. The results of the age stage, two-sex life table showed that the individuals in the pollen + yeast and pollen + yeast + sucrose groups had significantly higher oviposition period, fecundity, net reproductive rate (R0), and gross reproduction rate (GRR) than those in the pollen group. The results of the function response showed that the pollen + yeast + sucrose group was the most favorable for captive breeding of A. orientalis and had the best predatory ability along with rejuvenation and recovery ability. The results of the study provided a theoretical basis for indoor rearing, propagation, and utilization of A. orientalis.

The Toxicity Response of Coccinella septempunctata L. (Coleoptera: Coccinellidae) after Exposure to Sublethal Concentrations of Acetamiprid

Coccinella septempunctata is a nontarget beneficial arthropod and an important aphid predator in agricultural crops. In this study, the toxic effects of the neonicotinoid acetamiprid on C. septempunctata were investigated to determine its applicability and efficacy against the aphid predator. The results of the toxicity test showed that the second instar larvae of C. septempunctata were the most sensitive to acetamiprid. The LC50 values of the 1st, 2nd, 3rd, and 4th instar larvae were 15.767, 9.412, 18.850, and 25.278 mg a.i. L−1, respectively. Compared with that of the control, the predation ability of different larval instars was inhibited by sublethal concentrations of acetamiprid. The results of the predatory function test showed that sublethal concentrations of acetamiprid could reduce the consumption of aphids by fourth instar C. septempunctata larvae over a short duration and significantly inhibited the predatory ability of ladybird larvae. The results of the developmental test showed that sublethal concentration of acetamiprid shortened the growth duration of C. septempunctata larvae. Acetamiprid had considerable adverse effects on the different developmental stages of C. septempunctata. Together, our results provide information for implementation in biological and chemical control strategies for the integrated management of aphids.

Learning behavior of Neoseiulus californicus (Acari: Phytoseiidae) can help in adapting from feeding on alternative prey to target prey

Neoseiulus californicus (Acari: Phytoseiidae) is a commercialized predatory mite that is used as a biological control agent against Tetranychus urticae (Acari: Tetranychidae). Long-term feeding on alternative prey could impact the predatory capacity of N. californicus. Although most studies on the learning behavior of predatory mites have indicated that learning behavior could help them adapt from feeding on thrips (alternative prey) to spider mites (target prey), the role of learning behavior in adapting from feeding on astigmatid mites to spider mites has not been studied thus far. Therefore, this study explored the learning behavior of N. californicus in adapting from feeding on alternative prey (Oulenziella bakeri [Acari: Winterschmidtiidae]) to target mites (T. urticae). The attack latencies, prey preferences, and functional responses of female N. californicus were compared between two strains, N. californicus fed on T. urticae (TU) or O. bakeri (OB), and a learning behavior (LB) treatment. The results showed that the attack latency of OB strain was significantly longer than those of TU strain and LB treatment; OB strain did not show obvious prey preference between protonymphs of T. urticae and O. bakeri; and the functional response among TU, OB, and LB-treated strains were not significantly different. Our results demonstrated that long-term feeding on alternative prey had little effect on the predatory ability of N. californicus. To a certain extent, learning behavior can help N. californicus shift from feeding on alternative prey to target prey. Therefore, in the long run, it is reasonable to rear N. californicus on O. bakeri.

Feeding ecology of Amblychaeturichthys hexanema in Haizhou Bay based on linear mixed model

Many traditional economic marine fishery resources have been declining in the coastal waters of China. Amblychaeturichthys hexanema has become one of the dominant species in Haizhou Bay and some other coastal areas of China, playing an important role in marine food webs. We analyzed the feeding strategy of A. hexanema based on the bottom trawl surveys conducted in the Haizhou Bay and adjacent waters in spring and autumn of 2011 and 2013-2016. The feeding habits and main influencing factors of A. hexanema were studied using linear mixed model (LMM). The results showed that A. hexanema fed on 14 prey groups, with Amphipoda, shrimps, Bivalvia and Ophiuroidea as the main prey groups. A total of 37 species were identified in the preys. The dominant prey species were Gammarus sp., Leptochela gracilis, Monoculodes sp., Moerella iridescens and Alpheus distinguendus. Results of the linear mixed model showed that the feeding intensity of A. hexanema in Haizhou Bay was influenced by body length, water depth, survey season, and bottom water salinity. Among them, water depth and bottom salinity had significantly negative effects, whereas the impact of body length was significantly positive. The feeding intensity was significantly higher in spring than that in autumn. Results of cluster analysis showed that A. hexanema had different feeding habits between two length groups as divided by a threshold of 70 mm body length. The change of feeding habit was mainly attributed to the variations in predation ability and food availability. Feeding strategy analysis showed that trophic niche of A. hexanema had large components between phenotypes and low intraspecific competition for prey. This study would contribute to our understanding of life history characteristics and ecological habits of A. hexanema, and provide scientific support for the sustainable utilization and management.

Melanin Synthesis Pathway Interruption: CRISPR/Cas9-mediated Knockout of dopa decarboxylase (DDC) in Harmonia axyridis (Coleoptera: Coccinellidae).

CRISPR/Cas9 technology is a very powerful genome editing tool and has been used in many insect species for functional genomics studies through targeted gene mutagenesis. Here, we successfully established CRISPR/Cas9 research platform in Asian multi-colored ladybird beetle, Harmonia axyridis, an important natural enemy in biological control. In this study, one pivotal gene dopa decarboxylase (DDC) in melanin synthesis was targeted by CRISPR/Cas9 to generate mutants in H. axyridis by CRISPR/Cas9 technology. Our results showed that injection of single guide RNA of the DDC and Cas9 protein into preblastoderm eggs induced one insertion and four deletion (indels) mutant H. axyridis. Mutations of HaDDC gene generated 25% mutant rate with melanin missing phenotype in larva, pupa,l and adult stage. The predation ability of the fourth instar larvae has no significant difference between wild (control) and mutant H. axyridis (G0), while these mutant fourth instar larvae had longer developmental period than that of the wild type. Consequently, the total predation of the fourth instar larvae was significantly increased in H. axyridis mutants comparing with the wild type. These results indicated that the success of CRISPR/Cas9 gene editing in H. axyridis. The gene editing platform in H. axyridis would facilitate the gene function research and promote special strain of predatory ladybird beetle generation.

New Evidence of Tiger Subspecies Differentiation and Environmental Adaptation: Comparison of the Whole Genomes of the Amur Tiger and the South China Tiger.

Simple SummaryTigers are top predators and umbrella protectors, vital to the stability of ecosystems. The South China tiger has been declared extinct in the wild and only exists in captivity. The Chinese government is actively promoting the reintroduction of the South China tiger into the wild. The future of the wild population of the Amur tiger in China is not optimistic, and the recovery of the population is an essential task for the conservation of the Amur tiger. The recovery of the population is not only a macroscopic problem but also a significant study of molecular ecology. We used high-throughput sequencing technology to study the differences in adaptive selection between Amur tigers and South China tigers. Significant genetic differences were found between the Amur tiger and the South China tiger based on a principal component analysis and phylogenetic tree. We identified functional genes and regulatory pathways related to reproduction, disease, predation, and metabolism and characterized functional genes related to survival in the wild, such as smell, vision, muscle, and predatory ability. The data also provide new evidence for the adaptation of Amur tigers to cold environments. PRKG1 is involved in temperature regulation in a cold climate. FOXO1 and TPM4 regulate body temperature to keep it constant. The research also provides a molecular basis for future tiger conservation.Panthera tigris is a top predator that maintains the integrity of forest ecosystems and is an integral part of biodiversity. No more than 400 Amur tigers (P. t. altaica) are left in the wild, whereas the South China tiger (P. t. amoyensis) is thought to be extinct in the wild, and molecular biology has been widely used in conservation and management. In this study, the genetic information of Amur tigers and South China tigers was studied by whole-genome sequencing (WGS). A total of 647 Gb of high-quality clean data was obtained. There were 6.3 million high-quality single-nucleotide polymorphisms (SNPs), among which most (66.3%) were located in intergenic regions, with an average of 31.72% located in coding sequences. There were 1.73 million insertion-deletions (InDels), among which there were 2438 InDels (0.10%) in the coding region, and 270 thousand copy number variations (CNVs). Significant genetic differences were found between the Amur tiger and the South China tiger based on a principal component analysis and phylogenetic tree. The linkage disequilibrium analysis showed that the linkage disequilibrium attenuation distance of the South China tiger and the Amur tiger was almost the same, whereas the r2 of the South China tiger was 0.6, and the r2 of the Amur tiger was 0.4. We identified functional genes and regulatory pathways related to reproduction, disease, predation, and metabolism and characterized functional genes related to survival in the wild, such as smell, vision, muscle, and predatory ability. The data also provide new evidence for the adaptation of Amur tigers to cold environments. PRKG1 is involved in temperature regulation in a cold climate. FOXO1 and TPM4 regulate body temperature to keep it constant. Our results can provide genetic support for precise interspecies conservation and management planning in the future.

Potensi Ikan Barbir (Pethia conchonius) dan Lemon (Labidochromis caeruleus) Jantan dan Betina sebagai Predator Biologis Larva Nyamuk Aedes aegypti

Fish as natural predators of mosquito larvae is a way of controlling mosquito larvae biologically that does not pose a risk to the health of organisms and environmental damage and overcoming the problem of mosquito resistance to chemical larvacide. One fish tested in the study was the rosy barb (Pethia conchonius) and lemon cichlid (Labidochromis caeruleus). Objectives: To analyzed a difference in the predation ability of male and female fish to the larvae. Methods: This was an experimental study in the laboratory with a post-test-only design and five replications. One aquarium contains one liter of water, one fish, and 25 larvae of Ae. aegypti. Fish testing starts in the afternoon at 15.00 WIB. Observation the predation time of the fish until the fish eat all the larvae. Results: The average predation time of male P. conchonius fish was 1.57 minutes, and the female was 76.05 minutes. The average predation time of male L. caeruleus fish was 36.72 minutes and for females, 22.08 minutes. There was a significant difference between the predation of the male and female P. conchonius fish groups. There was no significant difference between the predation of male and female L. caeruleus fish groups to Ae. aegypti larvae. Conclusion: Rosy barb (P. conchonius) and lemon cichlid (L. caeruleus) have the potential to control the larval population of the Ae. aegypti mosquito. Rosy barb male has faster predation ability than other fish.Keywords: Aedes aegypti, female, Labidochromis caeruleus, Pethia conchonius, male

Underwater visibility constrains the foraging behaviour of a diving pelagic seabird.

Understanding the sensory ecology of species is vital if we are to predict how they will function in a changing environment. Visual cues are fundamentally important for many predators when detecting and capturing prey. However, many marine areas have become more turbid through processes influenced by climate change, potentially affecting the ability of marine predators to detect prey. We performed the first study that directly relates a pelagic seabird species's foraging behaviour to oceanic turbidity. We collected biologging data from 79 foraging trips and 5472 dives of a visually dependent, pursuit-diving seabird, the Manx shearwater (Puffinus puffinus). Foraging behaviour was modelled against environmental variables affecting underwater visibility, including water turbidity, cloud cover and solar angle. Shearwaters were more likely to initiate area-restricted search and foraging dives in clearer waters. Underwater visibility also strongly predicted dive rate and depth, suggesting that fine-scale prey capture was constrained by the detectability of prey underwater. Our novel use of dynamic descriptors of underwater visibility suggests that visual cues are vital for underwater foraging. Our data indicate that climate change could negatively impact seabird populations by making prey more difficult to detect, compounded by the widely reported effects of reduced prey populations.

Doru luteipes (Dermaptera: Forficulidae) and Orius insidiosus (Hemiptera: Anthocoridae) as Nocturnal and Diurnal Predators of Thrips.

Thrips (Thysanoptera, Thripidae) are pests of several crops and their chemical control is mainly hindered by their thigmotactic habits, which in turn allows the use of biological control agents with similar habits. Orius (Hemiptera: Anthocoridae) are effective control agents for thrips and are commercialized in many countries. Habitat overlap exists between Doru luteipes (Scudder) (Dermaptera: Forficulidae) and thrips, making D. luteipes a potential predator in the control of these insects. Our goals were to confirm the predatory ability of D. luteipes when exposed to thrips, Caliothrips phaseoli (Hood), and to evaluate the interaction between D. luteipes and Orius insidiosus Say for the control of thrips using behavioral and feeding preference tests. The ability of D. luteipes and O. insidiosus to prey on thrips at all stages was tested by predation bioassays; adults of D. luteipes consumed 210.9 ± 23.2 thrips per day, while adults of O. insidiosus consumed 32.4 ± 3.6 thrips per day. Intraguild predation was absent, and the predatory behavior feeding of the two predatory species was not altered in the presence of the other predator. In addition, these predators forage at different times-O. insidiosus during the day and D. luteipes at night, indicating that both predators do not interact negatively, allowing the use of both in a biological pest control program for thrips.

Sublethal exposure to pyriproxyfen does not impair the abilities of the backswimmer Buenoa amnigenus to prey upon Aedes aegypti larvae.

Pyriproxyfen is a juvenile hormone analogue that is commonly used to control the immature stages of mosquitoes in both artificial and natural water reservoirs. Recently, concerns have been raised regarding the community effectiveness of pyriproxyfen in preventing vector-transmitted diseases. Such concerns have been based on the unintended effects on non-target organisms and the selection of resistant mosquito populations. This investigation was, therefore, conducted to evaluate the toxicity of pyriproxyfen to Aedes aegypti (Diptera: Culicidae) larvae and the backswimmer Buenoa amnigenus (Hemiptera: Notonectidae), a naturally occurring mosquito larvae predator. We also assessed the abilities of backswimmers exposed to sublethal levels of pyriproxyfen to prey upon mosquito larvae (L2) under three larval densities (3, 6, or 9 larvae/100 mL of water) using artificial containers. Our results revealed that pyriproxyfen killed backswimmers only at concentrations higher than 100 μg active ingredient [a.i.]/L, which is 10 times higher than that recommended for larvicidal field application (i.e, 10 μg a.i./L). The abilities of backswimmers exposed to sublethal levels of pyriproxyfen (100 μg a.i./L) to prey upon mosquito larvae were not affected. Harmful effects on the backswimmer predatory abilities were detected only at concentrations of 150 μg a.i./L and when there was a higher prey availability (i.e., 9 larvae/100 mL of water). Together, our findings indicate that the reduced community effectiveness of this insecticide derives from factors other than its detrimental effects on non-target organisms such as backswimmers.

Predation on sentinel prey increases with increasing latitude in Brassica-dominated agroecosystems.

In natural ecosystems, arthropod predation on herbivore prey is higher at lower latitudes, mirroring the latitudinal diversity gradient observed across many taxa. This pattern has not been systematically examined in human‐dominated ecosystems, where frequent disturbances can shift the identity and abundance of local predators, altering predation rates from those observed in natural ecosystems. We investigated how latitude, biogeographical, and local ecological factors influenced arthropod predation in Brassica oleracea‐dominated agroecosystems in 55 plots spread among 5 sites in the United States and 4 sites in Brazil, spanning at least 15° latitude in each country. In both the United States and Brazil, arthropod predator attacks on sentinel model caterpillar prey were highest at the highest latitude studied and declined at lower latitudes. The rate of increased arthropod attacks per degree latitude was higher in the United States and the overall gradient was shifted poleward as compared to Brazil. PiecewiseSEM analysis revealed that aridity mediates the effect of latitude on arthropod predation and largely explains the differences in the intensity of the latitudinal gradient between study countries. Neither predator richness, predator density, nor predator resource availability predicted variation in predator attack rates. Only greater non‐crop plant density drove greater predation rates, though this effect was weaker than the effect of aridity. We conclude that climatic factors rather than ecological community structure shape latitudinal arthropod predation patterns and that high levels of aridity in agroecosystems may dampen the ability of arthropod predators to provide herbivore control services as compared to natural ecosystems.

Assessing the effect of complex ground types on ground-dwelling arthropod movements with video monitoring: Dealing with concealed movements under a layer of plant residues.

Understanding the effect of ground types on foraging movements of ground‐dwelling arthropods is a key step to managing their spatial distribution as required for successful conservation biological control. Indeed, fine movements at the centimeter scale can strongly influence the foraging ability of pest predators. However, because radio frequency identification or harmonic tracking techniques are not yet suitable for small species and video tracking focuses on uniform and light backgrounds, foraging movements have rarely been studied in relation to ground types. We present a method to track a ground‐dwelling arthropod (the earwig Euborellia caraibea) at night, walking on two contrasted ground types: bare soil and soil partly covered with a stratum of banana plant residues allowing individuals to hide periodically. The tracking of individuals within these ground types was achieved by infrared light, tagging individuals, video treatments, and semi‐automatic cleaning of trajectories. We tested different procedures to obtain segments with identical durations to quantify speeds and sinuosities. These procedures were characterized by the junction time gap between trajectory fragments, the rediscretization time of trajectories, and whether or not to use interpolation to fill in missing points in the trajectories. Earwigs exhibited significantly slower and more sinuous movements on soil with banana plant residues than on bare soil. Long time gaps for trajectory junction, extended rediscretization times, and interpolation were complementary means to integrate concealed movements in the trajectories. The highest slowdown in plant residues was detected when the procedure could account for longer periods under the residues. These results suggest that earwigs spent a significant amount of time concealed by the residues. Additionally, the residues strongly decreased the earwigs' movement. Since the technical solutions presented in this study are inexpensive, easy to set up, and replicate, they represent valuable contributions to the emerging field of video monitoring.

Numbers matter: Predatory ability increases with forager group size in omnivorous ant species with similar predatory traits

Abstract Predation is an important force structuring ecological communities. However, it is still controversial whether larger predator groups are more efficient at exploiting abundant resources. Here, we explored the association between the number of foragers and predation ability in generalist ant species that differ in forager numbers when exploiting resources. We conducted a field experiment by increasing caterpillar density around nests of two abundant Dorymyrmex ant species in the semiarid Patagonian steppe, where D. tener allocates a higher number of foragers to resource exploitation than D. antarcticus. We (1) compared the association between predation effectiveness (success to complete a task) and efficiency (speed of task performance and economy of foragers) with the number of foragers involved between species, and (2) studied how they responded numerically to increasing prey densities, by sequentially adding 3, 6 and 12 larvae in the same foraging arena. Finally, (3) we compared behavioural and morphological traits related to predation between these ant species. Although D. tener discovered a similar number of arenas with larvae than D. antarcticus, it was more effective as it recruited more and removed more larvae. This species was also more efficient than D. antarcticus in all predation subtasks, and the time used to remove one larva depended on prey density, being faster for the high‐larvae density. Besides the number of foragers, ant species did not differ in other behavioural traits, and D. tener's foragers were slightly larger than those of D. antarcticus. This study illustrates how, in social predators, the predator group size and individual behavioural characteristics may act in conjunction, with relevant consequences at ecological, evolutionary, and applied levels, including potential implications for pest control.

Sublethal toxicity, transgenerational effects, and transcriptome expression of the neonicotinoid pesticide cycloxaprid on demographic fitness of Coccinella septempunctata

Evaluating side effects of new neonicotinoids in terms of sublethal doses and transcriptome expression is a crucial but challenging part of integrated pest management (IPM) approaches. To this end, a study of lethal and sublethal effects on Coccinella septempunctata larvae was conducted, and an age-stage, two-sex life table procedure was performed to investigate life-table parameters. Cycloxaprid (CYC) was shown to have adverse effects on survival, development, total longevity, reproductive capacity, and predation ability in C. septempunctata. In addition, demographic growth parameters of the F1 generation such as net reproductive rate, and the intrinsic and finite rates of increase were significantly decreased under sublethal dosage LR30 (1.91 g ai/hm2). These results demonstrated that the population growth of C. septempunctata was impacted by a sublethal dosage of CYC. For transcriptome expression, 544 up- and 338 down-regulated significantly differentially expressed genes (DEGs), were observed between LR30 treatment and control groups. Moreover, pathways related to metabolism of retinol, carcinogenesis, biosynthesis of steroid hormone, P450 metabolism, and metabolism of xenobiotics were identified in KEGG pathway analysis. Ten DEGs were chosen and confirmed with quantitative real-time PCR analysis. Based on these findings, CYC should be considered as a component of IPM strategies in the field.

Practice does not make perfect: Juvenile object play does not improve the predation skills of adult mink in "simulated prey" tests.

In carnivores, juvenile object play is hypothesized to improve the development of adult predation ability. We tested this hypothesis in a model carnivore, the American mink (Neovison vison). Play was induced via the provision of diverse "enrichment" objects to 32 litters from 4 to 15weeks of age on a rotating schedule; control mink (32 litters) were instead provided with one static object. Behavioral observations confirmed that enriched juveniles engaged in more object play than control juveniles (p<.01). Tenacity, strength, and chasing motivations were assessed in 52 mink at 27-29weeks of age using five "simulated prey" tests. These tests showed internal consistency, with measures from the same test being weakly to very strongly correlated (r or ρ: |.33-.95|). Across tests assessing similar skills, some measures of tenacity and strength were also moderately correlated. Treatment had little effect, however, other than on maximum force during vertical pulling, in which control mink unexpectedly scored higher (1.01±0.06kg vs. 0.84±0.06kg, p=.0458). Although we did not find evidence to support the hypothesis that object play leads to improved predatory skills, the tests developed have the potential to be used in humane, prey-free future investigations of predation abilities.

Climate change does not decouple interactions between a central‐place‐foraging predator and its migratory prey

AbstractLittle is known about potential cascading effects of climate change on the ability of predators to exploit mobile aggregations of prey with a spatiotemporal distribution largely determined by climatic conditions. If predators employ central‐place foraging when rearing offspring, the ability of parents to locate sufficient prey could be reduced by climate change. In the Serengeti National Park, Tanzania, migratory species dominate mammalian herbivore biomass. These migratory herds exploit nutrient‐rich vegetation on the southern plains in the rainy season and surface water in the northwest in the dry season. Female spotted hyenas Crocuta crocuta breed throughout the year and use long‐distance central‐place‐foraging “commuting trips” to migratory herds to fuel lactation for ≥12 months. Changes in rainfall patterns that alter prey movements may decrease the ability of mothers to locate profitable foraging areas and thus increase their overall commuting effort, particularly for high‐ranking females that have priority of access to food resources within their clan territory and thus less commuting experience. In hyena clan territories, this may be reflected by a decrease in migratory herd presence and a decrease in the presence of lactating females, as maternal den presence represents the opposite of commuting effort. We investigated the strength of the relationship between rainfall volume, migratory herd presence in three hyena clan territories, and the responses of lactating females to this climate/prey relationship in terms of maternal den presence, using an observation‐based dataset spanning three decades. The probability of migratory herd presence in hyena clan territories increased with the amount of rainfall 2 months earlier, and maternal den presence increased with migratory herd presence. Rainfall volume substantially increased over 30 years, whereas the presence of migratory herds in hyena clans and the strength of the relationship between rainfall and migratory herd presence decreased. Hyenas thus adjusted well to the climate change‐induced decreased the presence of migratory herds in their territories, since maternal den presence did not decrease over 30 years and still matched periods of high prey abundance, irrespective of female social status. These results suggest a high plasticity in the response of this keystone predator to environmental variability.

Sublethal effects of tolfenpyrad on the development, reproduction, and predatory ability of Chrysoperla sinica

The lacewing, Chrysoperla sinica, is a predaceous insect that is important in crop pest management. Chemical pesticides have adversely impacted predaceous insect species. Here we studied the effect of tolfenpyrad on C. sinica. The acute toxicity of tolfenpyrad to the second-instar larvae was determined and indicated that tolfenpyrad is a medium-risk insecticide. Sublethal concentrations (LC10, LC20, and LC30) of tolfenpyrad had effects on the development, reproduction, and predatory ability of C. sinica. When the second-instar larvae of C. sinica were exposed to sublethal concentrations of tolfenpyrad, the activities of protective enzymes, such as superoxide dismutase, peroxidase, and catalase, and detoxification enzymes, including carboxylesterase, glutathione-S-transferase, and P450 monooxygenases, were increased with exposure time. The second-instar larvae of C. sinica exposed to sublethal concentrations of tolfenpyrad exhibited an oxidative stress response that increased the levels of malondialdehyde and reactive oxygen species (ROS). Within 48–120 h after treatment, the contents of mitochondrial respiratory chain complex I and adenosine triphosphate in the second-instar larvae were decreased. This resulted in an imbalance between the production and clearance of ROS and caused cellular damage.

Predation ability Toxorhynchites splendens larvae from Banjarbaru

The population of Toxorhynchites splendens in the rural area of the administrative city of Banjarbaru is quite abundant. This can be developed as part of the control management of Aedes sp. and Culex sp. as disease vectors. The purpose of this study was to test the predation ability of Tx. splendens against larvae of Ae. aegypti and Cx. quinquefasciatus and larval development time of Tx. splendens fed with larvae of Ae. aegypti and Cx. quinquefasciatus. The study used a completely randomized design with 10 replications. The results obtained were the predation ability of Tx. splendens larvae from instar 2 to pupae against larvae of Ae. aegypti and Cx. quinquefasciatus were 5.5 larvae/day and 6 larvae/day, respectively. The average length of the developmental phase of Tx. splendens larvae fed with Ae. aegypti and Cx. quinquefasciatus was 14.55 days and 12 days. The conclusion of this research is Tx. splendens originating from the city of Banjarbaru has the power of predation against Ae. aegypti and Cx. quinquefasciatus.

Predatory ability and abundance forecast the ecological impacts of two aquatic invasive species

Characterising interspecific interaction strengths, combined with population abundances of prey and their novel predators, is critical to develop predictive invasion ecology. This is especially true of aquatic invasive species, which can pose a significant threat to the structure and stability of the ecosystems to which they are introduced. Here, we investigated consumer-resource dynamics of two globally-established aquatic invasive species, European green crab (Carcinus maenas) and brown trout (Salmo trutta). We explored the mediating effect of prey density on predatory impact in these invaders relative to functionally analogous native rock crab (Cancer irroratus) and Atlantic salmon (Salmo salar), respectively, feeding on shared prey (Mytilus sp. and Tenebrio molitor, respectively). We subsequently combined feeding rates with each predator’s regional abundance to forecast relative ecological impacts. All predators demonstrated potentially destabilising Type II functional responses towards prey, with native rock crab and invasive brown trout exhibiting greater per capita impacts relative to their trophic analogues. Functional Response Ratios (attack rates divided by handling times) were higher for both invasive species, reflecting greater overall per capita effects compared to natives. Impact projections that incorporated predator abundances with per capita effects predicted severe impacts by European green crabs. However, brown trout, despite possessing higher per capita effects than Atlantic salmon, are projected to have low impact owing to currently low abundances in the sampled watershed. Should brown trout density increase sixfold, we predict it would exert higher impact than Atlantic salmon. Such impact-forecasting metrics and methods are thus vital tools to assist in the determination of current and future adverse impacts associated with aquatic invasive species.