Adult Predators Research Articles

HOPF BIFURCATION AND GLOBAL STABILITY OF A PREDATOR–PREY MODEL WITH ALTERNATIVE RESOURCE AND CANNIBALISM

In this study, we present a delayed predator–prey model with cannibalism including a prey, a juvenile predator and an adult predator. The adult predator hunts not only the prey but also the juvenile predator. The alternative resource is considered to reduce cannibalism in predator species. The main results are demonstrated by local stability and Hopf bifurcation. Sufficient criteria for local stability of the interior equilibrium point and the exhibition of a Hopf bifurcation are derived. Global stability is analyzed via designing a suitable Lyapunov function. Additionally, stability of the Hopf bifurcation is explored. Finally, numerical simulations are executed to validate the obtained results.

Heightened heart rate but similar flight responses to evolved versus recent predators in an Arctic seabird

Predator-prey dynamics in the Arctic are being altered with changing sea ice phenology. The increasing frequency of predation on colonial nesting seabirds and their eggs by the polar bear (<em>Ursus maritimus</em>) is a consequence of bears shifting to terrestrial food resources through a shortened seal-hunting season. We examined antipredator responses in a colony of nesting Common Eiders (<em>Somateria mollissima</em>) on East Bay Island, Nunavut, Canada, which is exposed to established nest predators, such as arctic fox (<em>Vulpes lagopus</em>), but also to recent increases in polar bear nest predation due to the bears’ lost on-ice hunting opportunities. Given eiders’ limited eco-evolutionary experience with bears, we aimed to experimentally contrast eider responses to the recent predation pressure by polar bears to those induced by their more traditional mammalian predator, the arctic fox. Our goal was to characterize whether this population of eiders was vulnerable to a changing predator regime. Using simulated approaches of visual stimuli of both predator types, we measured eider heart rate and flight initiation distance as physiological and behavioral metrics, respectively, to characterize the perceived risk of and subsequent response to imminent threat posed by these two predators that differ in historical encounter rates. Eider heart rates were more responsive to impending visual cues of arctic foxes compared to polar bears, but birds responded behaviorally to all simulated threats with similar flight initiation distances. Results suggest eiders may not perceive the full risk that bears pose as egg and adult predators, and are therefore expected to suffer negative fitness consequences from this ongoing and increasing interaction. Eiders may therefore require conservation intervention to aid in their management.

The Adult Tendency of Eleven-Spotted Ladybird, Coccinella undecimpunctata for Preference of Certain Type of Aphid

Ibrahim, A.K. 2023. The Adult Tendency of Eleven-Spotted Ladybird, Coccinella undecimpunctata for Preference of Certain Type of Aphid. Arab Journal of Plant Protection, 41(4): 369-374. https://doi.org/10.22268/AJPP-41.4.369374 This study explored the extent of eleven ladybirds preference to a specific aphid species, i.e., Aphis fabae, A. nerii, Macrosiphoniella sanborni and Hyalopterus pruni and the extent of the host plant and type of prey in attracting predators. Results obtained showed a preference of adult ladybird predators for H. pruni, Macrosiphoniella sanborni, Aphis nerii, whereas Aphis fabae was the least attractive and consumed by predators. The consumption rate of apricot aphid reached 23.66% in the presence of aphids and the host plant together. The most attraction to apricot leaves in the presence of the plant only was 55.90%. The time required for ladybirds to reach the first prey was 2.15 min for the apricot aphid in the presence of aphids and plants together. Furthermore, the ladybirds reached the prey within 1.30 minutes in the presence of aphids only. The predation efficiency of the four larval instars varied according to the type of aphids. It reached 86.30% for the fourth larval instar on apricot aphids and was the highest compared with the rest of the aphid species, which ranged between 7.10 and 84%. The general average predation efficiency values on aphids were 57.45% for H. pruni, 53.13% for Macrosiphoniella sanborni, 46.05% for A. nerii and 41.16% for A. fabae. The relative efficiency values for the larval instars reached 12.25, 42.27, 60.20 and 83.50%, respectively, for the first, second, third and fourth instars. This was confirmed by the high attraction of predatory ladybirds towards H. pruni and Macrosiphoniella sanborni, compared to Aphis nerii and Aphis fabea. The proportion of aphids consumed by ladybirds in the presence of the plant host was highest for H. pruni and lowest on Aphis fabea. Keywords: Aphids, ladybugs, plant host, predation efficiency

DYNAMICS OF ANTI-PREDATOR BEHAVIOR AND EFFECT OF FEAR ON PREY–PREDATOR MODEL

Predator–prey interactions are the ubiquitous and natural phenomenon in an ecological system. Predators reduce the prey population’s density by direct killing, which is an essential part of any ecological system. Based on the experimental works, for overcoming predation pressure, prey uses a variety of mechanisms. With Holling type-II functional response, we examined a prey–predator system incorporating anti-predator behavior and the cost of fear into prey. Prey anti-predator activity is a counterattacking strategy in which adult prey targets adolescent predators in order to counteract the potential predation pressure. Fear of predation may disrupt the physiological state of prey species and lead to long loss of prey species. In this study, we investigated this aspect to use a dynamical modeling approach. This research finds a plethora of fascinating phenomena. The studied system exhibits a wide range of dynamics and bifurcations, including saddle-node, Hopf, homoclinic, and a Bogdanov–Takens bifurcation in co-dimension two are among the dynamics and bifurcations observed in the analyzed system. We performed some numerical simulations to investigate the effects of anti-predator behavior and fear on prey and found both affect the prey–predator dynamics significantly. Our numerical examples clearly show that as prey carrying capacity increases, so does the prey’s ability to perceive the risk of predation.

Evaluation of prey stage preference of the phytoseiid predator, Neoseiulus longispinosus (Evans) to the spider mite pest, Tetranychus macfarlanei Baker and Pritchard (Acari: Tetranychidae)

Tetranychus macfarlanei Baker and Pritchard is considered as a major spider mite pest infesting various agricultural crops across the globe. It is a highly polyphagous species, inducing heavy yield loss annually, thereby affecting the agriculture sector drastically. As an eco-friendly pest management strategy, biological control using phytoseiid predators is gaining significant attention all over the world during the past few decades. Evaluation of predatory potential and prey stage preference provides valuable information on the efficacy of the predatory species in controlling the pest population. Considering this, a comparative evaluation of the feeding preference of a phytoseiid predator, Neoseiulus longispinosus (Evans), was made on different life stages of T. macfarlanei under laboratory conditions of 30±20C and 70±5% RH. The experimental arena used for the feeding experiments consisted of mulberry leaf discs (2 cm2) uniformly arranged over 2% semi-solidified agarose medium placed inside a glass Petri dish. The results revealed that the feeding preference of the adult predator towards the prey stages after 24 hours of experiment followed a decreasing sequence of egg (68%)&gt; nymph (13.3%)&gt; larva (6.6%). The predator nymph also followed a similar order of preference with respective consumption rates of 22%, 6.6% and 6.6% on the egg, larva and nymph of the prey mite, indicating that both the nymphs and the adult females of the predator displayed a significant preference to feed on the eggs of T. macfarlanei. Both predatory life stages showed no preference to the adult females of T. macfarlanei. Statistical analysis using ANOVA revealed a significant variation (p &lt; 0.05) in the feeding preference of the predatory life stages towards the varied prey stages. Thus, the results of the study clearly showed the bio-control potential of N. longispinosus against T. macfarlanei.

Stability Analysis of a Prey-Predator Model with Prey Refuge and Fear of Adult Predator

This paper is concerned with a Holling-II stage-structured predator-prey system in which predators are divided into an immature and mature predators. The aim is to explore the impact of the prey's fear caused by the dread of mature predators in a prey-predator model including intraspecific competitions and prey shelters. The theoretical study includes the local and global stability analysis for the three equilibrium points of the system and shows the prey's fear may lead to improving the stability at the positive equilibrium point. A numerical analysis is given to ensure the accuracy of the theoretical outcomes and to testify the conditions of stability of the system near the non-trivial equilibrium points.

Prevalence of Online Sexual Offenses Against Children in the US

Sexual abuse is increasingly facilitated by technology, but the prevalence and dynamics of such offenses have not been well delineated, making it difficult to design prevention strategies. To examine the frequency and characteristics of online and technology-facilitated sexual abuse against children and youth. In this nationally representative online survey study performed from November 19 to December 29, 2021, young adults aged 18 to 28 years were asked retrospectively about their childhood (<18 years) experiences of online and technology-facilitated abuse. The 2639 participants were sampled from an online panel. Participants were asked questions about 11 different kinds of online and technology-facilitated sexual abuse with follow-up questions about their dynamics and offenders. Prevalence rates were calculated for several cross-cutting concepts (online child sexual abuse, image-based sexual abuse, self-produced child sexual abuse images, nonconsensual sexting, online grooming by adults, revenge pornography, sextortion, and online commercial sexual exploitation). Survey weights were applied to obtain population prevalence estimates. A total of 2639 individuals (48.5% male, 49.8% female, and 1.8% other gender; 23.7% Hispanic, 12.6% non-Hispanic Black, 53.9% non-Hispanic White, 4.8% other race, and 5.0% ≥2 races) were surveyed. Childhood (before 18 years of age) prevalence rates were as follows: online child sexual abuse, 15.6% (SE, 1.0%); image-based sexual abuse, 11.0% (SE, 0.9%); self-produced child sexual abuse images, 7.2% (SE, 0.7%); nonconsensual sexting, 7.2% (SE, 0.7%); online grooming by adults, 5.4% (SE, 0.5%); revenge pornography, 3.1% (SE, 0.5%); sextortion, 3.5% (SE, 0.6%); and online commercial sexual exploitation, 1.7% (SE, 0.3%). The prime age of vulnerability across all categories was 13 to 17 years. Perpetrators in most categories were predominantly dating partners, friends, and acquaintances, not online strangers. The results of this national survey study suggest that a considerable portion of youth have experienced online child sexual abuse. Professionals planning prevention and intervention strategies for online sexual abuse should understand that dynamics include diverse episodes that are often extensions of dating abuse, sexual bullying, and sexual harassment, not only events perpetrated by adult internet predators.

High predation risk decimates survival during the reproduction season.

Predators attack conspicuous prey phenotypes that are present in the environment. Male display behavior of conspicuous nuptial coloration becomes risky in the presence of a predator, and adult males face higher predation risk. High predation risk in one sex will lead to low survival and sex ratio bias in adult cohorts, unless the increased predation risk is compensated by higher escape rate.Here, we tested the hypothesis that sand lizards (Lacerta agilis) have sex‐specific predation risk and escape rate. We expected the differences to manifest in changes in sex ratio with age, differences in frequency of tail autotomy, and in sex‐specific survival rate.We developed a statistical model to estimate predation risk and escape rate, combining the observed sex ratio and frequency of tail autotomy with likelihood‐based survival rate. Using Bayesian framework, we estimated the model parameters. We projected the date of the tail autotomy events from growth rates derived from capture–recapture data measurements.We found statistically stable sex ratio in age groups, equal frequency of tail regenerates between sexes, and similar survival rate. Predation risk is similar between sexes, and escape rate increases survival by about 5%. We found low survival rate and a low number of tail autotomy events in females during months when sand lizards mate and lay eggs, indicating high predator pressure throughout reproduction. Our data show that gravid females fail to escape predation.The risks of reproduction season in an ectotherm are a convolution of morphological changes (conspicuous coloration in males and body allometry changes in gravid females), behavior (nuptial displays), and environmental conditions which challenge lizard thermal performance. Performance of endotherm predators in cold spring months endangers gravid females more than displaying males in bright nuptial coloration.

When aggressiveness could be too risky: linking personality traits and predator response in superb fairy-wrens.

Personality syndromes in animals may have adaptive benefits for survival. For example, while engaging in predator deterrence, reactive individuals tend to prioritise their own survival, while proactive individuals engage in riskier behaviours. Studies linking animal personality measured in captivity with individual fitness or behaviours in the wild are sparse, which is a gap in knowledge this study aims to address. We used playback experiments in superb fairy-wrens (Malurus cyaneus), a common Australian songbird with a cooperative breeding system, to assess whether three personality traits measured during short-term captivity correlated with behavioural responses in the wild to a perceived nest and adult predator, the grey currawong (Strepera versicolor). We used three standard measures of personality in birds: struggle responses to human handling (boldness), exploration during a novel environment test, and aggressiveness during a mirror presentation. Superb fairy-wrens showed a significantly stronger response to the predator playback than to the control (willie wagtail, Rhipidura leucophrys) playback, suggesting that they recognised the predator playback as a threat without any accompanying visual stimulus. Birds that attacked their mirror image during the mirror presentation and those that spent a moderate amount of time close to the mirror responded more strongly to predator playback (by approaching the speaker faster and closer, spending more time near the speaker, and being more likely to alarm call) compared to those with low aggressiveness or those that spent very short or long durations close to the mirror. Neither boldness nor exploration in the novel environment test predicted playback response. Our results align with a growing number of studies across species showing the importance of animal personalities as factors for fitness and survival.

Drivers of within- and among-individual variation in risk-taking behaviour during reproduction in a long-lived bird.

Plastic and selective mechanisms govern parental investment adjustments to predation threat. We investigated the relative importance of plasticity and selection in risk-taking propensity of incubating female common eiders Somateria mollissima facing unprecedented predation in SW Finland, Baltic Sea. Using a 12-year individual-based dataset, we examined within- and among-individual variation in flight initiation distance (FID), in relation to predation risk, nest detectability, individual traits and reproductive investment (NFID = 1009; Nindividual = 559). We expected females nesting in riskier environments (higher predation risk, lower nest concealment) to mitigate environmentally imposed risk by exhibiting longer FIDs, and females investing more in current reproduction (older, in better condition or laying larger clutches) to display shorter FIDs. The target of predation-adult or offspring-affected the mechanisms adapting risk-taking propensity; females plastically increased their FID under higher adult predation risk, while risk-avoiding breeders were predominant on islands with higher nest predation risk. Risk-taking females selected thicker nest cover, consistent with personality-matching habitat choice. Females plastically attenuated their anti-predator response (shorter FIDs) with advancing age, and females in better body condition were more risk-taking, a result explained by selection processes. Future research should consider predator type when investigating the fitness consequences of risk-taking strategies.

Geographic Variation in Note Types of Alarm Calls in Japanese Tits (Parus minor).

Simple SummaryDivergence in acoustic signal systems might play a central role in speciation. Alarm calls are part of the acoustic signal system, which can transmit information about impending threats to group members and relatives. This study focuses on geographic variation in the note types of alarm calls in Japanese tits, a small songbird species distributed broadly in China. It was found that the note types of the same population responding to different intruders were roughly the same, and that all the three populations had shared note types and their own unique note types to warn about the same intruder. Moreover, we found large differences in the acoustic parameters of shared common note types among populations. These findings provide valuable information to improve the collective understanding of the evolutionary mechanisms of alarm call systems in birds.Geographic variability in acoustic signals has been documented in many bird species. However, geographic variations in alarm calls have been so far neglected despite their crucial role on reducing risk to group members and relatives. We analyzed the note types and acoustic parameters of Japanese tit (Parus minor) alarm calls to three types of intruders (a nest predator, an adult predator, and a harmless species) from three populations in China. Our results revealed that tits in the same population produce similar note types to different intruders, but the three populations only shared six note types and each population had unique note types. The frequency and duration parameters of three shared common note types were significantly different among populations. The three populations belong to the same species, thus they have shared note types. We suspect that the unique note types occurring in each population may be related to three potential reasons: founder effect, predation pressure, and vocal learning. The differences in acoustic parameters of common notes among populations may be a consequence of adaptations to their environments. We suggest that population differences in the note levels of bird alarm calls do exist.

Modeling total predation to avoid perverse outcomes from cat control in a data-poor island ecosystem.

Data hungry, complex ecosystem models are often used to predict the consequences of threatened species management, including perverse outcomes. Unfortunately, this approach is impractical in many systems, which have insufficient data to parameterize ecosystem interactions or reliably calibrate or validate such models. Here we demonstrate a different approach, using a minimum realistic model to guide decisions in data- and resource-scarce systems. We illustrate our approach with a case-study in an invaded ecosystem from Christmas Island, Australia, where there are concerns that cat eradication to protect native species, including the red-tailed tropicbird, could release meso-predation by invasive rats. We use biophysical constraints (metabolic demand) and observable parameters (e.g. prey preferences) to assess the combined cat and rat abundances which would threaten the tropicbird population. We find that the population of tropicbirds cannot be sustained if predated by 1607 rats (95% credible interval (CI) [103, 5910]) in the absence of cats, or 21 cats (95% CI [2, 82]) in the absence of rats. For every cat removed from the island, the bird's net population growth rate improves, provided that the rats do not increase by more than 77 individuals (95% CI [30, 174]). Thus, in this context, one cat is equivalent to 30-174 rats. Our methods are especially useful for on-the-ground predator control in the absence of knowledge of predator-predator interactions, to assess whether 1) the current abundance of predators threatens the prey population of interest, 2) managing one predator species alone is sufficient to protect the prey species given potential release of another predator, and 3) control of multiple predator species is needed to meet the conservation goal. Our approach demonstrates how to use limited information for maximum value in data-poor systems, by shifting the focus from predicting future trajectories, to identifying conditions which threaten the conservation goal. This article is protected by copyright. All rights reserved.

Stability Analysis of a Stage-Structure Predator–Prey Model with Holling III Functional Response and Cannibalism

This paper considers the time taken for young predators to become adult predators as the delay and constructs a stage-structured predator–prey system with Holling III response and time delay. Using the persistence theory for infinite-dimensional systems and the Hurwitz criterion, the permanent persistence condition of this system and the local stability condition of the system’s coexistence equilibrium are given. Further, it is proven that the system undergoes a Hopf bifurcation at the coexistence equilibrium. By using Lyapunov functions and the LaSalle invariant principle, it is shown that the trivial equilibrium and the coexistence equilibrium are globally asymptotically stable, and sufficient conditions are derived for the global stability of the coexistence equilibrium. Some numerical simulations are carried out to illustrate the main results.

Analisis Dinamik Model Predator-Prey dengan Struktur Usia dan Perilaku Anti-Predator

This article discusses the Predator-prey Holling type II model involving age structure and anti-predator behaviour. The age structure is given to the predator population, which is divided into two, namely juvenile predators and adult predators, while in the prey population, there is anti-predator behaviour, namely the tendency to defend against predator attacks. The model analysis includes the determination of a fixed point, analysis of the stability of the fixed point and numerical simulation. Three fixed points were obtained, namely the fixed point of population extinction (), the fixed point of predator extinction and the fixed point of population existence. Stability analysis shows that is always a saddle while and are conditionally stable. Furthermore, it is shown that the two conditions are both stable nodes. At the end, a simulation shows that the population dynamics that occur are highly dependent on the initial conditions of the population and the value of the anti-predator behaviour parameter of the prey population.

EFFECT OF DIFFERENT NATURAL MIXED MEDIA ON THE BIOLOGICAL CHARACTERISTICS OF THE GREEN LACEWING Chrysoperla carnea (STEPHENS)

The experiments were carried out in the laboratories of the mass rearing units of biological enemies Plant Protection Directorate / Ministry of Agriculture /Abu Ghraib in order to study the effect of different nutritional mixtures of media on some biological charecters of the adult predator Chrysoperla carnea(stephens). The results showed that the highest egg laying was obtained at the mixture (0.5 g yeast + 1.5 g Spirulina + 4g Honey + 0.5 Ml Water), reached to 881.33 eggs / female. In addition, the feeding on the mixture (0.5 g Spirulina + 4g Honey + 0.5 Ml Water) showed a positive effect in the incubation period of eggs, with an average of 3.54 days. The feeding on the mixture (0.5 g Ganoderma + 4g Honey + 0.5 Ml Water) resulted in better egg hatching ratio, reaching to 93.33%. A positive effect was shown with females’ survival when fed on the mixture (0.5 g yeast + 1.5 g Spirulina + 4g Honey + 0.5 Ml Water), the average longevity was 54 days. The longest male longevity was 36 days recorded at the mixed media of (0.5 g yeast + 1.5 g Spirulina + 4g Honey + 0.5 Ml Water). Longest post oviposition period was 5 days recorded at the mixed media of (1.5 g Spirulina + 4g Honey + 0.5 Ml Water). The longest period of eggs laying was at the mixture (Spiro Lina 1.5 g + yeast 0.5 g + honey 4 g + sterile distilled water 0.5 ml) was (46.47) days. Result indicated that some of the mixed media have a positive effect on the performance of aphid lion therefore; these combinations can be used in the quantitative mass rearing of the predator aphid lion.

Spodoptera litura (Lepidoptera: Noctuidae) rearing on artificial feed with Chrysoperla carnea predation (Neuroptera: Chrysopidae)

S. litura was reared on artificial meals in a controlled laboratory setting at 26.1°C, 16:8 h L:D, and 65.5% RH at the National Agricultural Research Center (NARC) in Islamabad, Pakistan, to evaluate its premature, mature adult stage characteristics and predation by C. cornea. On the artificial diet, the results for various parameters, including total larval duration (19.1 days, 45 percent), pre-pupal period (3.4 days, 92 percent), pupal period (7.05 days, 83 percent), and total immature duration from eggs to adult stage (33.4 days, 33 percent), as well as percent survival rate, were recorded. On a corn-based artificial diet, data on the pre-oviposition period (2.4 days), oviposition period (5.4 days), post-oviposition period (1.63 days), female fecundity (1366 eggs), and adult longevity (8.66 days) of mature stages of S. litura were collected. When supplied as prey, the predator's biological parameters and predatory capacity, C. carnea, were tested on two stages of S. litura (eggs and 1st instar larvae). The studies indicated that the prey significantly affected the total larval duration, immature duration, and % survival rate. The entire larval period was greatly minimized when C. carnea was offered eggs of S. litura for feeding. Additionally, higher % survival and fecundity were observed feeding with S. litura eggs, followed by 1st instar larvae. C. carnea consumed 443 S. litura eggs and 395 S. litura larvae during its larval development. Daily consumption of C. carnea larvae reached a maximum of 73 eggs and 53 1st instar larvae of S. litura. Comparatively, C. carnea larvae recorded maximum egg predation compared to 1st instar larvae of S. litura and the shorter developmental period when eggs were offered as prey. Moreover, 3rd instar larvae of C. carnea were found more voracious than early instars.

Everyone’s Accountable? Peer Sexual Abuse in Religious Schools, Digital Revelations, and Denominational Contests over Protection

Since the emergence of the #MeToo and #ChurchToo movements, online tracts have been employed to publicly reveal experiences of sexual abuse and assault among women and men in religious institutions and to shame abusers, which tend to be examined as an issue of women’s rights or child protection from adult predators. Drawing on the use of digital reporting platforms to testify against peer offences within religious schools, this paper asks how do such testimonies reveal adolescent agency and provoke policy re/actions about the accountability of religious institutions? Digital revelations submitted anonymously to Everyone’s Invited are analysed alongside interviews conducted with educators, parents, and youths in Jewish schools in Britain. Findings indicate how adolescent digital revelations of peer sexual abuse call for accountability by implicating the faith schools in question, which in turn triggers pedagogical and policy debates from educators. Public responses reflect diverging denominational positions on how to balance the protection of young people and safeguard religious self-protectionism. The paper spotlights the agency of youth in shaming peer abusers as much as faith schools and structures of religious authority, and in turn, how online shaming reveals frictions over accountability.

Assessment of endangered freshwater pearl mussel populations in the Northern Iberian Plateau in relation to non–native species: xenodiversity as a threat

In the last two decades, small populations of freshwater pearl mussels, Margaritifera margaritifera, have been recorded in Mediterranean rivers of the Iberian Northern Plateau. A survey was carried out in Castilla and León in 2018 to assess the development of populations of this species in all the rivers of known distribution and to update the threat classification. Thirty sections in the rivers Negro, Tera, Alberche and Águeda were positive for its presence, and another 50 stretches of seven rivers were negative. The species is currently distributed over about 22.5 km. Águeda and Tera populations have decreased dramatically in the last 14 years and are on the threshold of extinction. The Negro river supports the largest population, although the species has now disappeared in at least 61 % of the stretches that were inhabited in 2004. All populations showed very low densities and an ageing population structure, with no recruitment for decades. The presence of non-native invasive alien species (NIS) was higher than in a previous regional survey, with the signal crayfish representing the greatest threat. We observed changes in benthic microhabitats and direct predation of adults and glochidia conglutinates. In the Alberche River, in strict syntopy with M. margaritifera and two other mussel species, 10 NIS were detected. The current hydrological and ecological conditions in the Duero watershed support the settlement of exotic species to the disadvantage of native mollusks, which are more demanding in terms of microhabitats.

Biology and predation potential of the hemipteran predator, Rhynocoris marginatus (Fab., 1794) on the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

BackgroundThe notorious invasive pest fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), native to Americas entered the Asian continent and was first time reported on maize from India in 2018. The predatory species Rhynocoris marginatus (Fab.) (Hemiptera: Reduviidae) has been reported as a potential predator that preys on a number of economic pests in India such as Helicoverpa armigera (Hubner), Spodoptera litura (Fabricius), Mythimna separata (Walker), and Anomis flava (Fabricius). The present study described the biology and feeding potential of the predator on S. frugiperda under laboratory conditions where temperature and relative humidity varied from 26 to 28 °C and 75–80%, respectively, and the photoperiod was L12: D12 hrs.ResultsIncubation period and the total nymphal/developmental period of the predator were 9.65 and 55.89 days, respectively. The percentage of survivorship of nymphs to adults was 62.50%. Females showed a higher longevity than males. The predator’s fecundity reached 349.30 eggs/female, laid in 6 to 8 batches. Abdominal length and width were greater in the case of females than in males. Male consumed about 158.55 larvae of the fifth instar prey, at an average of 1.86 larvae per day. Females consumed a greater number of larvae (184.95) than males, with a higher daily predation rate of 1.93 larvae. Time taken to approach the prey was longer in the case of males (5.58 min) than females (3.57 min), whereas handling time was longer in females (115.37 min) than in males (85.71 min). Weight gained by females (61.90 mg) was higher than that by males (44.20 mg) after 24 h of predation.ConclusionsThe present study revealed that female adult predator and fifth-instar nymphs of R. marginatus preyed efficiently on S. frugiperda. The shorter ovipositional period of the predator was a positive sign for its mass multiplication, enabling rapid buildup of the predator population. This study is a step in the evaluation of the efficacy of R. marginatus feeding on fall armyworm. Further field studies are required on its mass release and effect in reducing the fall armyworm larval population.

Night-brooding behaviour in provisioning cavity-nesting birds is a trade-off between adult predation risk and nestling thermoregulation needs

Night-brooding of nestlings in cavity-nesting avian species carries predation risks to parents. Anecdotally, several species are known to shift from constant adult night-brooding behaviour to leaving nestlings unattended at night during offspring development but the timing, speed of change and sex-specific differences between parents, and the factors shaping this behaviour have rarely been described. Moreover, the location and nature of night roosts used by adults whilst provisioning nestlings has received little research attention. We studied breeding Common Starlings Sturnus vulgaris and hypothesised that, in such a cavity-nesting species, 1) nestlings would only be night-brooded until they achieved thermal independence, 2) since the species is frequently polygynous, female parents would most likely exclusively night-brood offspring despite provisioning by both sexes and 3) night-brooding would be more likely during nights with lowest temperatures. Nightly video recordings throughout the nestling phase at eight Starling nests together with data from 18 Starlings fitted with GPS-loggers during 26 nights provided support for hypotheses 1) and 2), while we found no support for hypothesis 3). All tagged male Starlings always roosted far from the nesting site (up to 8 km) independent of nestling age; all females brooded nestlings, usually up to the first seven-nine days after hatching (when the nestlings achieve thermoregulation), but roosted with males after day 10, when all tagged Starlings from the same nesting ‘colony’ roosted together. These results confirm differential sex-related parental effort in provisioning Starlings, suggesting females only night-brood until young achieve homeothermy.