Ability Of Predators Research Articles

In Situ Videography Quantifies Temporal and Spatial Variation in Prey Consumption and Energy Intake by Stream‐Dwelling Bull Trout (Salvelinus confluentus)

ABSTRACTIn stream ecosystems, invertebrates are a principal source of prey for many fishes, but their abundance as a food source depends on the predator's ability to exploit them in time and space. Although salmonid fishes are commonly thought of as daytime drift‐feeding predators of invertebrates in streams, they exhibit great flexibility in foraging behaviour and may also consume prey from the benthos and at night. Char species, (Salvelinus sp.), in particular, may be better adapted to forage under low light conditions due to greater scotopic sensitivity than other salmonids. In this study, we used in situ or in place videography to quantify the foraging behaviour of bull trout (Salvelinus confluentus) and determine when and where they capture prey. We found that bull trout were primarily daytime predators of invertebrates drifting in the water column, and that they rarely captured prey from the benthos or foraged at night. We did observe size‐related differences and seasonal declines in foraging rate from summer to fall months. A modelled estimate of energy intake indicates that daytime drift‐feeding by small size classes of bull trout was above that needed for a maximum daily ration under a range of assumptions about prey size and prey retention rates. Energy intake rates for larger fish were more dependent on assumptions of preferred prey size and prey retention rates. Our data indicate that daytime measures of invertebrate drift abundance and size are the most inclusive measure of food abundance for stream‐dwelling bull trout.

Cold storage of Aphidoletes aphidimyza can extend offspring larval development period and improve its predation ability

Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae) is widely used in aphid biological control, and low-temperature storage helps expand its population. Nonetheless, low-temperature effects on A. aphidimyza are unknown. A. aphidimyza pupae were exposed to three cold storage methods lasting 10, 20, and 30 days, respectively: storing at 7 °C for 4 h then 5 °C for 20 h (T1); storing at 9 °C for 4 h then 5 °C for 20 h (T2); and storing at 5 °C for 24 h (T3). The emergence rate under variable low-temperature storage (T1: 81.98%; T2: 81.28%) was significantly higher than that under constant low-temperature storage (T3: 74.98%). Additionally, the emergence rate decreased markedly with prolonged refrigeration time. Egg production at all three refrigeration temperatures declined significantly compared to the control treatment. It is noteworthy that low-temperature storage can significantly prolong the development time of offspring larvae without affecting the overall developmental period of the offspring. After comparing the content of cold-resistant substances in pupae under different low-temperature storage, the total sugar, glycerol, and trehalose increased with an extended storage time. The lifetime feeding capacity of A. aphidimyza offspring larvae on Myzus persicae (Sulzer) improved after cold storage. The functional response curve was aligned with the Holling Ⅱ model. Compared to the control treatment, both T1, T2, and T3 improved the search ability of 3rd-instar larvae in the offspring after 20 and 30 days of refrigeration. Our study indicated that cold storage of A. aphidimyza can extend offspring larval development period and improve its predation ability.

Potensi pengendalian larva nyamuk Aedes aegypti (Linnaeus) dengan menggunakan tiga varietas ikan cupang (Betta splendens)

Dengue fever (DF) is a viral disease transmitted by the Aedes aegypti (Linnaeus) mosquito, which has the fastest spreading cases. Drug and vaccines are still unavailable, so the Government is focusing on mosquito control. One method of biological control is to use betta fish (Betta splendens) as predators of Ae. aegypti larvae. Betta fish have various varieties, which may have different abilities in preying on Ae. aegypti larvae. The study aimed to analyze the potential for controlling Ae. aegypti larvae using three varieties of B. splendens fish (multi-colored plakat koi, xanthic morph plakat, and halfmoon varieties) during the day and evening. The test was carried out by inserting 25 Ae. aegypti larvaes into an aquarium containing B. splendens fish. Testing starts at 12.00 and 15.00 WIB and replicated five times. Observations started from the fish started preying on larvae until the fish ate all larvae. The predation ability of each variety of B. splendens fish based on predation time was analyzed using the one-way ANOVA test and the unpaired data t-test. The analysis showed that the multi-colored koi plakat variety preyed Ae. aegypti larvae faster than the xanthic morph plaque variety (P < 0.05) and not significantly different from the halfmoon variety (P > 0.05). There was no difference in the ability of B. splendens fish to prey larvae during the day and evening (P > 0.05). B. splendens fish, the multi-colored koi plaque variety, and the halfmoon variety can be biological predators of Ae. aegypti larvae.

Where to fly? Landscape influences on the movement and spatial ecology of a threatened apex predator

Effectively managing apex predators in human-modified landscapes poses considerable challenges. Habitat fragmentation disperses resources across wider expanses and undermines the ability of apex predators to reach isolated habitat patches as they traverse multi-tenured landscapes comprising unsuitable habitat. Understanding a species response to landscape configuration is key to informing effective management strategies, particularly for threatened, mobile and ecologically important species like apex predators. Here we use GPS tracking data collected from 37 powerful owls (Ninox strenua), an Australian threatened apex predator that occurs across the urban-agricultural-forest gradient, to investigate how landscape characteristics influence their spatial and movement behaviour. We demonstrate that as habitat fragmentation increases, the spatial requirements of powerful owls expand, their home-range shape becomes more intricate and individuals travel further each night, significantly adjusting their movement behaviours and spatial configurations to connect remaining habitat. Landscapes with unified and connected habitats, on the other hand, have smaller spatial requirements, likely due to greater habitat availability that minimises competition for essential resources. This facilitates the establishment of smaller home-ranges and consequently, the occurrence of more territories. Interestingly, landscape characteristics did not influence sequential nightly visitation behaviour, suggesting that powerful owls across all landscape types visit different portions of their home-range each night to exert an unpredictable hunting strategy regardless of local landscape conditions. Our research highlights the importance of integrating the influence of local landscape features and visitation behaviours into decision-making processes. This integration is crucial for informing effective conservation strategies aimed at supporting apex predator survival in disturbed landscapes.

Birds and bats reduce herbivory damage in Papua New Guinean highland forests.

Insectivorous predators, including birds and bats, play crucial roles in trophic cascades. However, previous research on these cascades has often relied on permanent predator exclosures, which prevent the isolation of specific effects of birds and bats, given their different activity patterns throughout the day. Moreover, limited knowledge exists regarding the variations in individual effects of these predators under different biotic and abiotic conditions, such as changes in elevation. To address these uncertainties, our study aimed to investigate the distinct effects of bats and birds on arthropod densities in foliage and herbivory damage in lowland and highland rainforests of Papua New Guinea (PNG). Predator exclosures were established for one month to exclude diurnal or nocturnal predators across 120 saplings (ca. 2.5-4 m tall) selected from two lowland and two highland forests (i.e., 30 saplings per study site) along the Mt. Wilhelm transect in PNG. Arthropods were collected and measured, and herbivory damage was analyzed at the end of the experiment. Birds significantly reduced arthropod densities by 30%, particularly in arthropods longer than 10 mm, regardless of elevation. Additionally, both birds and bats appeared to mitigate herbivory damage in highland forests, with protected saplings displaying up to 189% more herbivory. Our results support previous studies that have demonstrated the ability of insectivorous predators to reduce leaf damage through the control of arthropods. Furthermore, our approach highlights the importance and necessity of further research on the role of seasons and elevations in trophic cascades.

Functional and Numerical Responses of Harmonia axyridis (Coleoptera: Coccinellidae) to Rhopalosiphum nymphaeae (Hemiptera: Aphididae) and Their Potential for Biological Control.

The water lily aphid (Rhopalosiphum nymphaeae) is a highly polyphagous herbivore that causes severe damage to many terrestrial and aquatic plants, especially lotus. Due to environmental concerns about water pollution and other issues caused by chemical control methods, there is an urgent need to develop effective and sustainable control methods. The harlequin ladybird (Harmonia axyridis) is a well-known aphid predator and may pose a potential threat to R. nymphaeae. To study the predation ability of H. axyridis at different developmental stages on R. nymphaeae, we assessed the functional response, attack rate, and search effect of H. axyridis larvae and adults preying on R. nymphaeae. The numerical response of this process was also evaluated under a constant ladybird-to-aphid ratio and constant aphid density conditions, respectively. Our results showed that all predator stages exhibited type II functional responses. The predation rate of individual H. axyridis on R. nymphaeae nymphs significantly increased as prey density increased. In contrast, the search effect of H. axyridis gradually decreased with an increase in prey density. Meanwhile, H. axyridis at different developmental stages possess varying predation abilities; fourth instar and adult H. axyridis were found to be highly efficient predators of R. nymphaeae. H. axyridis adults exhibited the highest predation ability and predation rate, while both the adult and fourth-instar larvae exhibited the highest attack rate. Moreover, fourth-instar larvae exhibited the highest search effect value at initially lower prey densities, although adults surpassed them at higher prey densities. Our results also indicated that H. axyridis exhibited varying degrees of intraspecific interference and self-interference influence as predator density increases. These results strongly support H. axyridis as an effective biocontrol agent for R. nymphaeae.

Toxic effects of cadmium on the growth and predation capacity of the predator Orius sauteri

The heavy metal cadmium (Cd) leads to significant bottom-up effects on food chains of plants, herbivores, and predators in agroecosystems. Through the transfer and accumulation of Cd. In addition to the indirect effects of this cascading effects, predators Orius sauteri fed with artificial diets containing Cd also have a direct effect. We found that O. sauteri fed with sucrose solutions containing Cd at high concentrations of 125 mg/L and 625 mg/L significantly decreased the survival of the 3rd and 5th instar, female, and male adults (except 125 mg/L) of O. sauteri. However, the survival of O. sauteri nymphs was significantly increased when they fed with low concentrations of 1 mg/L, 5 mg/L and 25 mg/L Cd sucrose solutions. Cd stress has differing effects on the LC50 of each age of O. sauteri, the lowest LC50 for male adults (153 mg/L), followed by 3rd instar nymphs (192 mg/L), 5th instar nymphs (289 mg/L) and female adults (383 mg/L). It is interesting that 1 mg/L, 5 mg/L, and 25 mg/L of sucrose solutions containing Cd significantly improved the predation capacity of the nymphs of O. sauteri to the Bemisia tabaci pupa. The predation ability of the male adults of O. sauteri on B. tabaci pupa were significantly improved, but significantly decreased in the female adults when they fed with 125 mg/L and 625 mg/L sucrose solutions containing Cd. This difference needs to be studied in depth in the future, controlling Cd contamination and protecting natural enemies to enhance the biological control of pests.Graphical

An evaluation of the growth, development, reproductive characteristics and pest control potential of three Trichogramma species on Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae).

Tuta absoluta is an invasive alien species that has caused major losses in the Chinese tomato industry. Investigating the growth, development, reproduction and pest control effects of three native species of Trichogramma species on the eggs of T. absoluta could provide an ecological tool for preventing and controlling T. absoluta in China. In this study, we constructed age-stage two-sex life tables for three common species of Trichogramma and determined their relative abilities to control T. absoluta in greenhouse insect cages, thus allowing us to identify the species with the most effective ability to prey on T. absoluta eggs. Analysis showed that the net reproductive rate (R0), gross reproduction rate (GRR) and intrinsic rate of increase (r) of Trichogramma ostriniae were the highest of the three species at 22.85, 32.58 and 1.31, respectively. In the presence of 10 eggs and under ideal conditions, T. ostriniae, Trichogramma chilonis, and Trichogramma dendrolimi produced 9451.04, 5199.56, and 1902.95 offspring, respectively. Following the release of T. ostriniae, tomato leaves incurred a damage index of 1 after the first week, while the number of T. absoluta reduced to 24.60 individuals by week 10 (8.75% of the control treatment). Of the three species of Trichogramma tested in this study, T. ostriniae exhibited the best growth, development, reproductive capacity and predatory ability against T. absoluta, and has broad application prospects. © 2024 Society of Chemical Industry.

Bdellovibrio’s prey-independent lifestyle is fueled by amino acids as a carbon source

Identifying the nutritional requirements and growth conditions of microorganisms is crucial for determining their applicability in industry and understanding their role in clinical ecology. Predatory bacteria such as Bdellovibrio bacteriovorus have emerged as promising tools for combating infections by human bacterial pathogens due to their natural killing features. Bdellovibrio’s lifecycle occurs inside prey cells, using the cytoplasm as a source of nutrients and energy. However, this lifecycle supposes a challenge when determining the specific uptake of metabolites from the prey to complete the growth inside cells, a process that has not been completely elucidated. Here, following a model-based approach, we illuminate the ability of B. bacteriovorus to replicate DNA, increase biomass, and generate adenosine triphosphate (ATP) in an amino acid-based rich media in the absence of prey, keeping intact its predatory capacity. In this culture, we determined the main carbon sources used and their preference, being glutamate, serine, aspartate, isoleucine, and threonine. This study offers new insights into the role of predatory bacteria in natural environments and establishes the basis for developing new Bdellovibrio applications using appropriate metabolic and physiological methodologies.Key points• Amino acids support axenic lifestyle of Bdellovibrio bacteriovorus.• B. bacteriovorus preserves its predatory ability when growing in the absence of prey.

Inhibition of convergence of mimicry rings by low learning abilities of predators

Inhibition of convergence of mimicry rings by low learning abilities of predators

Control of schistosomiasis by the selective competitive and predatory intervention of intermediate hosts: A mathematical modeling approach

Schistosomiasis, a freshwater-borne neglected tropical disease, disproportionately affects impoverished communities mainly in the tropical regions. Transmission involves humans and intermediate host (IH) snails. This manuscript introduces a mathematical model to probe schistosomiasis dynamics and the role of non-host snail competitors and predators as biological control agents for IH snails. The numerical analyses include investigations into steady-state conditions and reproduction numbers associated with uncontrolled scenarios, as well as scenarios involving non-host snail competitors and/or predators. Sensitivity analysis reveals that increasing snail mortality rates is a key to reducing the IH snail population and control of the transmission. Results show that specific snail competitors and/or predators with strong competition/predation abilities reduce IH snails and the subsequent infectious cercaria populations, reduce the transmission, and possibly eradicate the disease, while those with weaker abilities allow disease persistence. Hence our findings advocate for the effectiveness of snail competitors with suitable competitive pressures and/or predators with appropriate predatory abilities as nature-based solutions for combating schistosomiasis, all while preserving IH snail biodiversity. However, if these strategies are implemented at insignificant levels, IH snails can dominate, and disease persistence may pose challenges. Thus, experimental screening of potential (native) snail competitors and/or predators is crucial to assess the likely behavior of biological agents and determine the optimal biological control measures for IH snails.

Urea regulates soil nematode population by enhancing the nematode-trapping ability of nematode-trapping fungi

As the most abundant animal in the soil, nematodes are directly or indirectly involved in almost all soil ecological processes. Studying soil nematode population regulation is essential to understanding soil ecological processes. This study found urea combines nematode-trapping fungi to regulate the population of soil nematodes. In soil, compared with no urea, adding 0.2 mg/mL urea after applying Arthrobotrys oligospora and Dactylellina ellipsospora reduced the number of nematodes by 34.7% and 31.7%. Further, the mechanism of urea couple nematode-trapping fungi to regulate the nematode population was explored in the medium environment. The results showed that the addition of 0.2 mg/ml urea accelerated the trap formation of A. oligospora and D. ellipsosporas by 50% and 46.5%, and increased the yield of traps of A. oligospora and D. ellipsosporas by 39.5% and 40.6%, thus, the predatory efficiency of A. oligospora and D. ellipsospora on nematodes was increased by 34.2% and 32.7%. In conclusion, urea regulates the predation ability of A. oligospora and D. ellipsosporas to regulate the soil nematode population. This study deepens the understanding of the regulatory pathways of the soil nematodes but also provides a potential new strategy for harmful nematode bio-control.

Proactive cursorial and ambush predation risk avoidance in four African herbivore species.

Most herbivores must balance demands to meet nutritional requirements, maintain stable thermoregulation and avoid predation. Species-specific predator and prey characteristics determine the ability of prey to avoid predation and the ability of predators to maximize hunting success. Using GPS collar data from African wild dogs, lions, impala, tsessebes, wildebeest and zebra in the Okavango Delta, Botswana, we studied proactive predation risk avoidance by herbivores. We considered predator activity level in relation to prey movement, predator and prey habitat selection, and preferential use of areas by prey. We compared herbivore behaviour to lion and wild dog activity patterns and determined the effect of seasonal resource availability and prey body mass on anti-predator behaviour. Herbivore movement patterns were more strongly correlated with lion than wild dog activity. Habitat selection by predators was not activity level dependent and, while prey and predators differed to some extent in their habitat selection, there were also overlaps, probably caused by predators seeking habitats with high prey abundance. Areas favoured by lions were used by herbivores more when lions were less active, whereas wild dog activity level was not correlated with prey use. Prey body mass was not a strong predictor of the strength of proactive predation avoidance behaviour. Herbivores showed stronger anti-predator behaviours during the rainy season when resources were abundant. Reducing movement when top predators are most active and avoiding areas with a high likelihood of predator use during the same periods appear to be common strategies to minimize predation risk. Such valuable insights into predator-prey dynamics are only possible when using similar data from multiple sympatric species of predator and prey, an approach that should become more prevalent given the ongoing integration of technological methods into ecological studies.

Laboratory Evaluation of Predation Potency Euborellia Annulata (Dermaptera: Anisolabididae) on Larvae of Spodoptera Frugiperda (Lepidoptera: Noctuidae), a Pest of Maize Crops

Spodoptera frugiperda is an invasive pest found attacking corn plants in Indonesia in 2019. The pest attacks during the vegetative and generative periods and can cause heavy crop damage. Biological control by utilizing predators is an environmentally friendly control method. Euborellia annulata is a predator found in maize crops. This study was conducted to determine the predation potency of E. annulata on S. frugiperda larvae. This study arranged as a completely randomized design (CRD) with 5 treatments, 1 male E. annulata adult, 1 female E. annulata adult, 2 male E. annulata adult, 2 female E. annulata adult and 1 pair of male and female E. annulata adult. Ten S. frugiperda instar 3 larvae were placed in the treatment containers, then predator E. annulata was placed into the containers according to the treatment. Variables observed were the number of S. frugiperda larvae preyed and the predation behavior of E. annulata. The results showed that at 4 Days After Treatment (DAT) there was a significant difference in the predation ability of E. annulata on S. frugiperda larvae. At 5 DAT, 2 female E. annulata showed greater predation ability at 66% compared to treatment 2 male E. annulata at 52%. However, 2 female E. annulata showed the similar prey ability as 1 pair of male and female adult at 7 and 8 DAT with a mortality range of 96-100% of S. frugiperda. Predators with the female have a large prey ability and are more aggressive than the male. Morphologically, it is known that the forceps of female predators are larger than males, so that female predators are faster to prey on S. fungiperda. Female predators and have better prey potency as biological control agents for S. fungiperda pests in maize crops.

Comparative anatomy of the caudate nucleus in canids and felids: Associations with brain size, curvature, cross-sectional properties, and behavioral ecology.

The evolutionary history of canids and felids is marked by a deep time separation that has uniquely shaped their behavior and phenotype toward refined predatory abilities. The caudate nucleus is a subcortical brain structure associated with both motor control and cognitive, emotional, and executive functions. We used a combination of three-dimensional imaging, allometric scaling, and structural analyses to compare the size and shape characteristics of the caudate nucleus. The sample consisted of MRI scan data obtained from six canid species (Canis lupus lupus, Canis latrans, Chrysocyon brachyurus, Lycaon pictus, Vulpes vulpes, Vulpes zerda), two canid subspecies (Canis lupus familiaris, Canis lupus dingo), as well as three felids (Panthera tigris, Panthera uncia, Felis silvestris catus). Results revealed marked conservation in the scaling and shape attributes of the caudate nucleus across species, with only slight deviations. We hypothesize that observed differences in caudate nucleus size and structure for the domestic canids are reflective of enhanced cognitive and emotional pathways that possibly emerged during domestication.

In vitro evaluation of the potential of mites of the family Macrochelidae (Acari: Mesostigmata) as macrobiological agents against the nematode Haemonchus contortus (Strongylida: Trichostrongylidae)

Small ruminants (sheep and goats) constantly suffer from endoparasitoses caused by gastrointestinal nematodes. Among these, the species Haemonchus contortus (Rudolphi, 1803) is considered to be the one of greatest importance within sheep farming. This nematode is difficult to control due to its resistance to most commercial anthelmintics. The aim of the present study was to assess the potential of macrochelid mites as macrobiological agents for controlling endoparasitoses of sheep caused by the nematode, H. contortus. For this, novel in vitro methodology was used, in which assessments were made not only of the predatory ability but also the population growth of mite species (Macrocheles merdarius, Macrocheles robustulus and Holostaspella bifoliata) when offered larvae of the nematode, H. contortus. The predatory ability of the mites, M. merdarius and H. bifoliata were efficient regarding their predatory ability against H. contortus nematode larvae. The mite, M. merdarius exhibited the highest predation rate with mean distribution values for the treated group of 18656 ± 10091 and for the control group of 1178 ± 712 (P < 0.0001). The species, H. bifoliata presented the highest population growth rate, with a percentage acarid recovery rate of 263% in relation to the number added initially. The data from this in vitro predation experiment suggest that, M. merdarius and H. bifoliata showed promise as macrobiological agents for controlling gastrointestinal endoparasitoses of sheep caused by the nematode, H. contortus given that both species reduced the population of this helminth by more 70% and the number of mites recovered was three times greater than the number added.

Sealing the deal - Antarctic fur seals' active hunting tactics to capture small evasive prey revealed by miniature sonar tags.

The ability of predators to adopt hunting tactics that minimise escape reactions from prey is crucial for efficient foraging, and depends on detection capabilities and locomotor performance of both predators and prey. Here, we investigated the efficiency of a small pinniped, the Antarctic fur seal (Arctocephalus gazella) at exploiting their small prey by describing for the first time their fine-scale predator-prey interactions. We compared these with those from another diving predator, the southern elephant seal (Mirounga leonina) that forage on the same prey type. We used data recorded by a newly developed sonar tag that combines active acoustics with ultrahigh-resolution movement sensors to study simultaneously the fine-scale behaviour of both Antarctic fur seals and prey during predator-prey interactions in more than 1200 prey capture events for eight female Antarctic fur seals. Our results showed that Antarctic fur seals and their prey detect each other at the same time, i.e. 1-2 s before the strike, forcing Antarctic fur seals to display reactive fast-moving chases to capture their prey. In contrast, southern elephant seals detect their prey up to 10 s before the strike, allowing them to approach their prey stealthily without triggering an escape reaction. The active hunting tactics used by Antarctic fur seals is probably very energy consuming compared with the stalking tactics used by southern elephant seals but might be compensated for by the consumption of faster-moving larger prey. We suggest that differences in manoeuvrability, locomotor performance and detection capacities and in pace of life between Antarctic fur seals and southern elephant seals might explain these differences in hunting styles.

From predator to protector: Myxococcus fulvus WCH05 emerges as a potent biocontrol agent for fire blight.

Fire blight, caused by the Gram-negative bacterium Erwinia amylovora, poses a substantial threat to pome fruit production worldwide. Despite existing control strategies, a pressing need remains for sustainable and environmentally friendly fire blight management. Myxobacteria, renowned for their predatory behavior and potent enzymes, emerge as a groundbreaking biocontrol approach with significant potential. Here, we report the biocontrol potential of a novel Myxococcus fulvus WCH05, against E. amylovora. Using various in vitro and planta assays, we demonstrated the multifaceted biocontrol abilities of strain WCH05. In plate predation assays, strain WCH05 exhibited not only strong predation against E. amylovora but also broad-spectrum activities against other plant pathogenic bacteria. Pre-treatment with strain WCH05 significantly decreased pear blossom blight incidence in detached inflorescence assays, achieving a controlled efficacy of 76.02% that rivaled the antibiotic streptomycin (79.79%). In greenhouse trials, strain WCH05 effectively reduced the wilting rate and disease index in young pear seedlings, exhibiting both protective (73.68%) and curative (68.66%) control. Further investigation revealed that the biocontrol activity of strain WCH05 relies on both direct contact and extracellular enzyme secretion. While cell extracts lacked inhibitory activity, ammonium sulfate-precipitated secreted proteins displayed potent lytic activity against E. amylovora. Substrate spectrum analysis identified peptidases, lipases, and glycosidases among the secreted enzymes, suggesting their potential roles in pathogen degradation and biocontrol efficacy. This study presents the first evidence of Myxococcus fulvus WCH05 as a biocontrol agent against fire blight. Its potent predatory abilities and enzymatic arsenal highlight its potential for sustainable disease management in pome fruit production. Future research will focus on identifying and characterizing specific lytic enzymes and optimizing strain WCH05 application strategies for field efficacy.

Oviposition and larval performance of Chrysoperla carnea S. on four natural preys with emphasis to life tables

Chrysoperla carnea is an important insect predator which globally have significant role in integrated pest management. The experiment was investigated the biology and life table parameters of predator on four natural preys (namely: Aphis gossypii, A. durantae, Brevicoryne brassicae and Ferrisia virgata) under laboratory conditions. The life table data of predator was analyzed according to the age-stage, two-sex life table method 2023. The results indicated the effect of tested preys on biology of C. carnea. On F. virgata, the development of predatory females and males was recorded the longest one. The longest oviposition period of predator was recorded on A. durantae and B. brassicae. The predatory insect gave the highest reproduction rate when fed on all three tested aphids. Life expectancy for female stage was recorded maximum of (71.0 days) on B. brassicae. This study indicated to ability of predator to overcome on the tested prey which attack several economic vegetable crops and ornamental plants.

A Long Photoperiod Promoted the Development, Reproduction, and Predation of Harmonia axyridis Pallas (Coleoptera: Coccinellidae) at an Average Greenhouse Temperature during the Winter.

To explore the feasibility of adjusting the photoperiod to regulate the life parameters and predation ability of Harmonia axyridis Pallas in greenhouses during the winter, life tables were constructed for H. axyridis under the three following photoperiods: 9L:15D (light/dark), 12L:12D, and 16L:8D at 15 °C, an average greenhouse temperature during the winter when aphids severely damage vegetables. The effects of photoperiods on predation by this ladybird were tested in both laboratory and greenhouse settings. The results showed that increased illumination promoted the development and reproduction of H. axyridis; under medium and long photoperiods, the pre-adult periods were 3.61 days and 4.34 days shorter than that under the short photoperiod, respectively, and the fecundity increased by 1.78 and 2.41 times. Population parameters r, λ, and R0 increased as illumination time increased, whereas T decreased. Increased illumination also increased the predation by third- and fourth-instar larvae and adults. The amounts of predation by fourth-instar larvae and adults increased by 22.16% and 75.09% under the medium photoperiod, and those under the long photoperiod increased by 71.96% and 89.64%, respectively. The numbers of Myzus persicae Sulzer predated by H. axyridis under the long photoperiod were higher than those under the short photoperiod in a greenhouse, and the predation parameters were influenced.