Gimme Walter

Why female birds of prey are larger than males

Publisher: Oxford University Press (OUP)

Date: 15-03-2023

DOI: 10.1093/BIOLINNEAN/BLZ201

Abstract: The causes of the reversed sexual size dimorphism (RSD females larger than males) in birds of prey are subject to a centuries-old, passionate debate. A crucial difficulty is to distinguish whether the postulated benefits derive from the proposed causal process(es) or are incidental. After reviewing the existing literature, we present a methodology that overcomes this difficulty and renders unnecessary any speculative a priori distinctions between evolved function and incidental effects. We can thus justify the following novel version of the well-known nest defence hypothesis as the most likely to explain the phenomenon in all birds of prey that show RSD: if the female predominates in actively defending the eggs and young against predators, then she is the heavier sex, and her relatively greater body mass is adaptive. That is, heavier females are favoured (independently of males) by natural selection. The attractiveness of this hypothesis is that it has the potential to explain the phenomenon in all raptors exhibiting RSD, can deal with the exceptional cases in this group, explains the direction of the dimorphism, focuses on a key factor in the reproductive success of most raptors, is parsimonious, i.e. does not require supporting hypotheses, and is supported by a substantial body of evidence.

Complete chloroplast genome sequences of two species of Chloris grass, Chloris truncata Sw. and Chloris virgata R.Br

Publisher: Informa UK Limited

Date: 2017

DOI: 10.1080/23802359.2016.1266705

Complete chloroplast genome sequences of six lines of Echinochloa colona (L.) link

Publisher: Informa UK Limited

Date: 2017

DOI: 10.1080/23802359.2016.1261612

Ecology of the Grey Falcon Falco hypoleucos – current and required knowledge

Publisher: Informa UK Limited

Date: 08-09-2020

DOI: 10.1080/01584197.2019.1654393

Diel activity patterns and arrestment behaviour in host associations of green mirids (Creontiades dilutus)

Publisher: Cambridge University Press (CUP)

Date: 10-06-2021

DOI: 10.1017/S0007485320000322

Abstract: Many plant bugs (Miridae) are generalist herbivores that feed on multiple host species. The reasons these bugs move across hosts and the behavioural mechanisms responsible for their retention at specific hosts remain elusive. Green mirids ( Creontiades dilutus ) are endemic to Australia. These insects are important pests of cotton ( Gossypium hirsutum ) and even in low numbers can cause substantial damage to crops. These bugs are also present in relatively much higher numbers on pigeon pea ( Cajanus cajan ) planted alongside cotton fields, and evidence shows they move across these crops in both directions. Observations of these highly mobile insects in the field are challenging, but indirect evidence suggests that they may be nocturnal. This study evaluated: (1) the diel (24 h) period in which C. dilutus adults were most active, (2) whether they respond to plant volatiles immediately prior to landing on host substrates, and (3) if their presence on a host is in response to attraction or arrestment cues. The results suggest that C. dilutus bugs are typically most active early in the evenings, after remaining motionless during the day (unless disturbed). Their movement (at night) was arrested by hosts prior to touching plant tissues. There was no evidence to suggest that these bugs are attracted by volatiles beyond 2 cm. These outcomes demonstrate that insect behaviours need to be investigated within their typical activity periods, and that arrestment cues possibly play a central role in the host finding process of generalist C. dilutus and probably, therefore, other mirid species.

Inferring Invasion Paths Into Cotton by Creontiades dilutus (Hemiptera: Miridae) From Arid Zone and Agricultural Sources

Publisher: Oxford University Press (OUP)

Date: 05-11-2019

DOI: 10.1093/EE/NVZ126

Abstract: Managing agricultural pests that use multiple host plant species is a challenge when in iduals move between host plants in natural vegetation and agricultural environments. The green mirid (Creontiades dilutus) Stål (Hemiptera: Miridae) is endemic to Australia and routinely invades cotton from local uncultivated vegetation, but may also originate from remote locations in the arid continental interior. This bug is polyphagous and highly mobile, which contributes to its pest status in cotton L. (Malvaceae) systems as well as its persistence in arid environments with sparsely distributed ephemeral host plants. The aim of this study was to evaluate how C. dilutus in iduals use a variety of host species across remote arid regions and highly managed agricultural landscapes. Structured field surveys spanning vast areas across the Simpson Desert in the arid heart of Australia, as well as subcoastal cotton production systems, were designed to evaluate host use across environments that share few plant species. High numbers of C. dilutus were collected from Cullen australasicum (Schltdl.) J.W.Grimes (Fabaceae) (perennial hosts) and Goodenia cycloptera R.Br. (Goodeniaceae) (ephemeral hosts) in the desert following rain. In agricultural environments, C. dilutus bugs were mostly found on irrigated Medicago sativa L. (Fabaceae) (lucerne), and to a lesser extent Melilotus indicus (L.) All. (Fabaceae) near rivers. Significantly, bugs were on these plants prior to the planting of cotton across all environments surveyed. These data allow inferences relating host use, host abundance, and insect migration to one another to understand the connection that C. dilutus bugs have between arid and agricultural environments.

Validating Eaton's Hypothesis: Cubane as a Benzene Bioisostere

Publisher: Wiley

Date: 05-02-2016

DOI: 10.1002/ANGE.201510675

Delayed juvenile behavioral development and prolonged dependence are adaptations to desert life in the grey falcon

Publisher: Oxford University Press (OUP)

Date: 11-01-2022

DOI: 10.1093/CZ/ZOAC001

Abstract: Rapid learning in the young of most endothermic animals can be expected to be favored by natural selection because early independence reduces the period of vulnerability. Cases of comparatively slow juvenile development continue, therefore, to attract scientific attention. In most species of birds, including raptors, the young depend on their parents for some time after fledging for the provisioning of food and for protection while they learn to become nutritionally and otherwise independent. Among raptors, post-fledging dependence periods that exceed 6 months are exclusive to the largest species and these have reproductive cycles that exceed 12 months. By contrast, young of the medium-sized grey falcon Falco hypoleucos have been reported in close company with their parents up to 12 months after fledging, that is, at a time when the adults are expected to breed again. We investigated the occurrence and characteristics of prolonged adult–juvenile association relative to other falcons and similar-sized raptors. We found that the behavioral development of grey falcon young is extremely delayed, and that they even depend nutritionally on their parents for up to 12 months after fledging. We suggest that these 2 distinctive features are, ultimately, adaptations of the grey falcon to its extreme environment, Australia’s arid and semi-arid zone, one of the hottest environments in the world.

Characterising the variables associated with Tribolium castaneum adults that initiate flight in laboratory tests – Generating predictions for the field

Publisher: Elsevier BV

Date: 12-2018

DOI: 10.1016/J.JSPR.2018.10.005

Complete chloroplast genome of glyphosate resistant Conyza bonariensis (L.) Cronquist from Australia

Publisher: Informa UK Limited

Date: 25-07-2017

DOI: 10.1080/23802359.2017.1357441

Effects of sublethal phosphine exposure on respiration rate and dispersal propensity of adult females of Tribolium castaneum

Publisher: Springer Science and Business Media LLC

Date: 15-06-2020

DOI: 10.1007/S10340-019-01133-5

Frontispiz: Validating Eaton's Hypothesis: Cubane as a Benzene Bioisostere

Publisher: Wiley

Date: 29-02-2016

DOI: 10.1002/ANGE.201681161

Host interaction mechanisms in herbivorous insects – life cycles, host specialization and speciation

Publisher: Oxford University Press (OUP)

Date: 04-07-2022

DOI: 10.1093/BIOLINNEAN/BLAC070

Abstract: Why are most herbivorous insects so specialized? How do generalists and specialists differ ecologically? And what sensory and cognitive processes determine which host species an insect recognizes and uses? We review sensory cues involved at different stages of interaction with host plants and outline a unified scheme of insect–host interaction mechanisms. Generalist species may be best understood as specialized organisms with a longer tail of secondary host species that they accept to a lessening extent. Secondary hosts have fewer attractive cues, and hence a lower probability of meeting the stimulation threshold required for egg laying. We then discuss the alternative theories of co-evolution and sequential evolution used to explain the ersification of insect herbivores. We conclude that ‘escape and radiate’ co-evolution rests on unrealistic assumptions and empirical evidence favours sequential evolution of plants and herbivores, and the unique life cycles of insect herbivores may sufficiently explain their extreme ersity within the animal kingdom. We also outline a new speciation-oriented hypothesis to explain why specialists are far more erse than generalists. Generalists tend to have large, contiguous distributions and therefore lower speciation rates. Natural selection in novel environments may also result in narrowing of the host range more often than broadening, further increasing specialist ersity.

Interactions of Helicoverpa punctigera (Lepidoptera: Noctuidae) Larvae and Adults With Four Native Host Plants Relative to Field Use Patterns

Publisher: Oxford University Press (OUP)

Date: 21-12-2020

DOI: 10.1093/EE/NVAA160

Abstract: Generalist insect herbivores may be recorded from a great variety of host plants. Under natural conditions, however, they are almost invariably associated with a few primary host species on which most of the juveniles develop. We experimentally investigated the interaction of the generalist moth Helicoverpa punctigera Wallengren (Lepidoptera: Noctuidae) with four of its native host plants, two designated primary hosts and two secondary hosts (based on field observations). We tested whether primary host plants support higher survival rates of larvae and whether they are more attractive to ovipositing moths and feeding larvae. We also evaluated whether relative attractiveness of host plants for oviposition matches larval survival rates on them—the preference-performance hypothesis. Moths laid significantly more eggs on two of the four host plant species, one of them a primary host, the other a secondary host. Larvae developed best when reared on the attractive secondary host, developed at intermediate levels on the two primary hosts, and performed worst on the less attractive secondary host. Relative attractiveness of the four host plants to caterpillars differed from that of the moths. Neither adult nor larval attraction to host plants fully supported the preference-performance hypothesis, but oviposition was better correlated with larval survival rates than was larval attraction. Our results suggest the relative frequency at which particular host species are used in the field may depend on factors not yet considered including the long-distance attractants used by moths and the relative distribution of host species.

Coping with heat in the arid interior – what can feather structure reveal about the ecology of Australia’s desert-living Grey Falcon Falco hypoleucos?

Publisher: Informa UK Limited

Date: 12-12-0019

DOI: 10.1080/01584197.2019.1698301

Different Species Requirements within a Heterogeneous Spring Complex Affects Patch Occupancy of Threatened Snails in Australian Desert Springs

Publisher: MDPI AG

Date: 21-10-2020

DOI: 10.3390/W12102942

Abstract: (1) The distribution of organisms that inhabit patchy systems is dictated by their ability to move between patches, and the suitability of environmental conditions at patches to which they disperse. Understanding whether the species involved are identical to one another in their environmental requirements and their responses to variance in their environment is essential to understanding ecological processes in these systems, and to the management of species whose patchy and limited distributions present conservation risks. (2) Artesian springs in Australia’s arid interior are “islands” of hospitable wetland in uninhabitable “oceans” of dry land and are home to erse and threatened assemblages of endemic species with severely restricted distributions. Many have strict environmental requirements, but the role of environmental heterogeneity amongst springs has rarely been considered alongside conventional patch characteristics (isolation and patch geometry). (3) We quantified environmental heterogeneity across springs, and the relationship between spring size, isolation (distances to neighbours) and environmental quality (depth, water chemistry), and patterns of occupancy and population persistence of six endemic spring snail species, all from different families, and with all restricted to a single ha system of springs in Australia. To do so, a survey was conducted for comparison against survey results of almost a decade before, and environmental variables of the springs were measured. Many of the snail species occupied few sites, and environmental variables strongly covaried, so an ordination-based approach was adopted to assess the relationship between environmental measures and the distribution of each species, and also whether springs that held a higher ersity of snails had specific characteristics. (4) Each snail species occupied a subset of springs (between 5% and 36% of the 85 s led) and was associated with a particular set of conditions. Of the six species considered in further detail, most were restricted to the few springs that were large and deep. Species in family Tateidae were distinct in having colonised highly isolated springs (with m to nearest neighbour). Springs with highest ersity were significantly larger, deeper and had more numerous neighbours within 300 m than those devoid of endemic snails, or those with low ersity. (5) Although spring size and isolation affect patterns of occupancy, the six snail species had significantly different environmental requirements from one another and these correlated with the distribution pattern of each. Approaches that ignore the role of environmental quality—and particularly depth in springs—are overlooking important processes outside of patch geometry that influence ersity. These organisms are highly susceptible to extinction, as most occupy less than 3 ha of habitat spread across few springs, and habitat degradation continues to compromise what little wetland area is needed for their persistence.

Tests of hybridisation in Tetragonula stingless bees using multiple genetic markers

Publisher: Cold Spring Harbor Laboratory

Date: 09-03-2020

DOI: 10.1101/2020.03.08.982546

Abstract: Discrepancies in mitochondrial and nuclear genetic data are often interpreted as evidence of hybridisation. We re-examined reports of hybridisation in three cryptic stingless bee species in the genus Tetragonula in South East Queensland, Australia ( T. carbonaria, T. davenporti , and T. hockingsi ). Previous studies on this group using microsatellite markers proposed that occasional hybrids are found. In contrast, we find that allele frequencies at neutral regions of the nuclear genome, both microsatellites and random snps , reliably separated the three species, and thus do not support hybridisation. We found no inter-species variation in PCR licons of the nuclear gene EF1alpha , but low and moderate species-specific polymorphisms in the nuclear gene Opsin and the mitochondrial 16S respectively, with no cases of mito-nuclear discordance at these genes. We confirm that nuclear ergence between these species is low, based on 10-26kb of non-coding sequence flanking EF1alpha and Opsin (0.7-1% pairwise difference between species). However, we find mitogenomes to be far more erged than nuclear genomes (21.6-23.6% pairwise difference between species). Based on these comprehensive analyses of multiple marker types, we conclude that there is no ongoing gene flow in the Tetragonula species of South East Queensland, despite their high morphological similarity to one another and the low nuclear ergence among them. The mitogenomes and draft nuclear genomes provided for these species will be a resource for further molecular studies on this group, which are important pollinators in Australian natural and agroecosystems.

Migration dynamics of an important rice pest: the brown planthopper (Nilaparvata lugens) across Asia – insights from population genomics

Publisher: Cold Spring Harbor Laboratory

Date: 08-03-2020

DOI: 10.1101/2020.03.07.981894

Abstract: Brown planthoppers ( Nilaparvata lugens ) are the most serious insect pests of rice, one of the world’s most important staple crops. They reproduce year-round in the tropical parts of their distribution, but cannot overwinter in the temperate areas where they occur, and invade seasonally from elsewhere. Decades of research has not revealed their source unambiguously. We therefore sequenced the genomes of brown planthopper populations from across temperate and tropical parts of their distribution and show that the Indochinese peninsula is the major source of migration into temperate China. The Philippines, once considered a key source, is not significant, with little evidence for their migration into China. We find support for immigration from the west of China contributing to these regional dynamics. The lack of connectivity between the Philippines and mainland China explains the different evolution of Imidacloprid resistance in these populations. This study highlights the promise of whole genome sequence data to understand migration when gene flow is high – a situation that has been difficult to resolve using traditional genetic markers.

Migration dynamics of an important rice pest: The brown planthopper (Nilaparvata lugens) across Asia—Insights from population genomics

Publisher: Wiley

Date: 11-07-2020

DOI: 10.1111/EVA.13047

Multiple invasions of a generalist herbivore—Secondary contact between two divergent lineages of Nezara viridula Linnaeus in Australia

Publisher: Wiley

Date: 22-06-2020

DOI: 10.1111/EVA.12971

Testing mate recognition through reciprocal crosses of two native populations of the whiteflyBemisia tabaci(Gennadius) in Australia

Publisher: Cambridge University Press (CUP)

Date: 23-10-2019

DOI: 10.1017/S0007485319000683

Abstract: Bemisia tabaci (Gennadius) represents a relatively large cryptic species complex. Australia has at least two native populations of B. tabaci sensu lato and these were first found on different host plants in different parts of Australia. The species status of these populations has not been resolved, although their mitochondrial sequences differ by 3.82–4.20%. We addressed the question of whether these AUSI and AUSII B. tabaci populations are distinct species. We used reciprocal cross-mating tests to establish whether the insects from these different populations recognize one another as potential mating partners. The results show that the two native Australian populations of B. tabaci have a mating sequence with four phases, each of which is described. Not all pairs in the control crosses mated and the frequency of mating differed across them. Some pairs in the AUSI-M × AUSII-F did mate (15%) and did produce female progeny, but the frequency was extremely low relative to controls. Microsatellite genotyping of the female progeny produced in the crosses showed these matings were successful. None of the AUSII-M × AUSI-F crosses mated although some of the males did search for females. These results demonstrate the critical role of the mate recognition process and the need to assess this directly in cross-mating tests if the species status of different populations is to be tested realistically. In short, AUSI and AUSII B. tabaci populations are distinct species because the in idual males and females do not recognize in iduals of the alternative population as potential mating partners.

Responses of diamondback moth to diverse entomopathogenic fungi collected from non-agricultural habitats – Effects of dose, temperature and starvation

Publisher: Elsevier BV

Date: 10-2022

DOI: 10.1016/J.FUNBIO.2022.08.005

Abstract: We evaluated the virulence of Beauveria bassiana and Metarhizium isolates from soil collected across different vegetation types in Queensland, against chlorantraniliprole-resistant and insecticide-susceptible diamondback moth (DBM) larvae. Host insecticide resistance status had no effect on susceptibility to the pathogens when conidia were topically applied to larvae in the laboratory, and one B. bassiana isolate was significantly more virulent to larvae than the others (seven days after inoculation). The influence of temperature (15, 20, 25 or 30 °C): (i) at the point of host inoculation with conidia and (ii) when the pathogens had already initiated infection and were proliferating in the host haemocoel, was determined experimentally for its influence on virulence, disease progression, and sporulation. Temperature at inoculation had a greater effect on host insect mortality than it did when the fungus was already proliferating in the host haemocoel. The rearing temperature of hosts prior to inoculation had a greater effect on host susceptibility to disease than starvation of the larvae at the time of inoculation. Our results also show that each fungal isolate has its own temperature relations and that these can vary considerably across isolates, and at different points in the pathogen life cycle (germination and cuticular penetration versus growth in the host haemocoel). Temperature also had an idiosyncratic effect, across isolates and across the variables typically used to assess the potential of fungal entomopathogens as biological control agents (time to death, mortality and sporulation rates). This study demonstrates that in addition to pathogenicity and virulence, the temperature relationships of each fungal isolate when infecting insects needs to be taken into account if we are to understand their ecology and use them effectively in pest management.

Validating Eaton's Hypothesis: Cubane as a Benzene Bioisostere

Publisher: Wiley

Date: 05-02-2016

DOI: 10.1002/ANIE.201510675

Abstract: Pharmaceutical and agrochemical discovery programs are under considerable pressure to meet increasing global demand and thus require constant innovation. Classical hydrocarbon scaffolds have long assisted in bringing new molecules to the market place, but an obvious omission is that of the Platonic solid cubane. Eaton, however, suggested that this molecule has the potential to act as a benzene bioisostere. Herein, we report the validation of Eaton's hypothesis with cubane derivatives of five molecules that are used clinically or as agrochemicals. Two cubane analogues showed increased bioactivity compared to their benzene counterparts whereas two further analogues displayed equal bioactivity, and the fifth one demonstrated only partial efficacy. Ramifications from this study are best realized by reflecting on the number of bioactive molecules that contain a benzene ring. Substitution with the cubane scaffold where possible could revitalize these systems, and thus expedite much needed lead candidate identification.

Significant population structure in Australian Cryptolestes ferrugineus and interpreting the potential spread of phosphine resistance

Publisher: Elsevier BV

Date: 06-2018

DOI: 10.1016/J.JSPR.2018.05.004

Online Learners’ Reading Ability Detection Based on Eye-Tracking Sensors

Publisher: MDPI AG

Date: 10-09-2016

DOI: 10.3390/S16091457

Assessment of relative host plant quality for three cryptic species of the Bemisia tabaci species complex in Australia

Publisher: Springer Science and Business Media LLC

Date: 02-09-2021

DOI: 10.1007/S11829-021-09863-Z

Origins, Divergence, and Contrasting Invasion History of the Sweet Potato Weevil Pests Cylas formicarius (Coleoptera: Brentidae) and Euscepes batatae (Coleoptera: Curculionidae) in the Asia-Pacific

Publisher: Oxford University Press (OUP)

Date: 28-07-2019

DOI: 10.1093/JEE/TOZ198

Abstract: Cylas formicarius F. and Euscepes batatae Waterhouse are the most damaging sweet potato insect pests globally. Both weevils are thought to have invaded the Pacific alongside the movement of sweet potato (Ipomoea batatas (L.) Lam. Convolvulaceae), with C. formicarius having originated in India and E. batatae in Central or South America. Here we compare the genetic relationships between populations of the pests, primarily in the Asia-Pacific, to understand better their contemporary population structure and their historical movement relative to that of sweet potato. Cylas formicarius has ergent mitochondrial lineages that indicate a more complex biogeographic and invasive history than is presently assumed for this insect, suggesting it was widespread across the Asia-Pacific before the arrival of sweet potato. Cylas formicarius must have originally fed on Ipomoea species other than I. batatas but the identity of these species is presently unknown. Cylas formicarius was formerly designated as three species or subspecies and the genetic data presented here suggests that these designations should be reinvestigated. Euscepes batatae has very low genetic ersity which is consistent with its historical association with sweet potato and a recent introduction to the Asia-Pacific from the Americas. The distribution of E. batatae may be narrower than that of C. formicarius in the Asia-Pacific because it has relied relatively more on human-assisted movement. Consequently, E. batatae may become more widespread in the future. Investigating the invasion history of both species will help to understand the probability and nature of future invasions.

The Gene Introgression Approach and the Potential Cost of Genes that Confer Strong Phosphine Resistance in Red Flour Beetle (Coleoptera: Tenebrionidae)

Publisher: Oxford University Press (OUP)

Date: 14-03-2020

DOI: 10.1093/JEE/TOAA033

Abstract: Resistance in pest insects to the grain fumigant phosphine (PH3) poses a threat to trade and food security. The possible pleiotropic effects of PH3 resistance on development and reproduction were investigated in the red flour beetle, Tribolium castaneum (Herbst), by introgressing two genes known to be major contributors to strong resistance (tc_rph1 and tc_rph2) into a susceptible background. The tc_rph2 allele was the G135S variant, whereas the identity of tc_rph1 allele was unknown but could have been one of the three known variants (L119W, V123F, or S349G). The introgressed resistant strain was 288× more resistant than the susceptible strain, based on mortality after a 20 h fumigation with PH3. Molecular screening confirmed that the introgressed strain was homozygous for the resistance genes, but was otherwise indistinguishable from the susceptible strain based on screening with 12 neutral DNA markers. We found no differences of consequence in developmental time between the susceptible and introgressed resistant strains. Similarly, the number of F1 adults produced by these strains was more or less equal, as was the weight of in idual F1 adults. The conclusions remained the same regardless of whether the experiments were conducted on a flour-based medium or wheat. Thus, we found no evidence that being fully strongly PH3 resistant (i.e., homozygous for tc_rph1 and tc_rph2) has major consequences in terms of development or reproduction in T. castaneum.

Phylogeography of the rare Australian endemic Grey Falcon Falco hypoleucos: implications for conservation

Publisher: Cambridge University Press (CUP)

Date: 26-02-2020

DOI: 10.1017/S0959270920000106

Abstract: The Grey Falcon Falco hypoleucos is one of the world’s rarest raptors, with an estimated population size of fewer than 1,000 in iduals. Our knowledge of threats posed to the Grey Falcon remains scant. Understanding the genetic variation in this species would help to assess its conservation status more realistically and its prospects for survival in a changing environment. We lified the cytochrome b region of mitochondrial DNA from the feathers of 26 in iduals captured from the wild across the distribution of the species and assessed the genetic ersity and spatial genetic structuring of the species. Genetic ersity was low, with only six haplotypes identified, but there was no evidence of a recent genetic bottleneck. No population genetic structuring was detected, indicating that the Grey Falcon population is effectively continuous across the species’ entire distribution, covering much of Australia’s arid/semi-arid zone. Our results indicate that the Grey Falcon should be managed as a single population and suggest conservation efforts that benefit the species at a local level should be good for the species as a whole. Future studies should employ next generation sequencing approaches, which may provide finer-scale information on the extent these birds move among breeding sites. Further research into the species’ ecology is also required to identify effective conservation measures.

Frontispiece: Validating Eaton's Hypothesis: Cubane as a Benzene Bioisostere

Publisher: Wiley

Date: 29-02-2016

DOI: 10.1002/ANIE.201681161

Flight of three major insect pests of stored grain in the monsoonal tropics of India, by latitude, season and habitat

Publisher: Elsevier BV

Date: 03-2018

DOI: 10.1016/J.JSPR.2017.12.005

Low activity levels are an adaptation to desert-living in the Grey Falcon, an endotherm that specializes in pursuing highly mobile prey

Publisher: Elsevier BV

Date: 2022

DOI: 10.1016/J.JTHERBIO.2021.103108

Abstract: Endothermic animals that live permanently in hot deserts must avoid harmful hyperthermia when their body temperature increases from heat gained through external and internal sources. This is true particularly for endotherms that are exclusively diurnal. We investigated the Grey Falcon (Falco hypoleucos), a predatory Australian endemic restricted to the hot arid/semi-arid zone. To understand how this species' entire population persists exclusively and permanently in this extreme environment we examined its activity levels and compared these with equivalent variables from the Peregrine Falcon (F. peregrinus), a cosmopolitan species that inhabits similar environments without being restricted to them. Further, we compared, across a selected group of Falco species, specific plumage characteristics (measured on museum specimens) that we anticipated would enhance the Grey Falcons' ability to cope with high heat loads. We found no morphological or physiological characteristics that would allow them to cope with heat better than other birds, but the chicks seem to have unusually high thermal tolerances. Grey Falcons do, however, possess a suite of unusual behavioural adaptations that, as we propose, enable them to cope with climatic extremes in arid environments. Specifically, throughout their lives Grey Falcons keep activity levels and thus physical exertion low. This behaviour contrasts strikingly with that of the Peregrine Falcon, which also actively hunts birds in flight. Keeping activity levels low is expected to minimize endogenous heat production and thus ease the Grey Falcon's thermoregulation during periods of high heat load. These birds may rely on low levels of relative humidity for efficient evaporative cooling, and this may explain their absolute restriction to hot arid/semi-arid zones.

Has the Australian Endemic Grey Falcon the Most Extreme Dietary Specialization among all Falco Species?

Publisher: MDPI AG

Date: 19-06-2022

DOI: 10.3390/ANI12121582

Abstract: A clear understanding of a species’ diet is crucial in understanding its spatio-temporal dynamics, and is, therefore, pertinent to conservation considerations. The diet of the Grey Falcon (Falco hypoleucos), a rare and threatened predator endemic to the Australian arid and semi-arid zone, is subject to erging assertions therefore, we studied its diet through direct observation of food ingestion during more than 17 years of fieldwork across the species’ distribution. We found that Grey Falcons of all ages fed almost exclusively on a single type of food, namely, birds, and non-avian food items never constituted a substantial portion of any in idual’s diet. The extraordinary circumstances that were associated with the ingestion of non-avian food suggest strongly that, across its vast distribution, throughout the year, and throughout its life, the Grey Falcon feeds almost exclusively on birds. Further, we compared the diets of all Falco species and found that the dietary specialization is most extreme in the Grey Falcon, more so than even in the Taita (F. fasciinucha) and Peregrine Falcons (F. peregrinus). Based on aspects of the species’ environment and relative prey availability, we offer an evolutionary explanation of the apparently unique dietary specialization of the arid-adapted Grey Falcon.

Inter-colony fights in Tetragonula stingless bees result in temporary mixed-species worker cohorts

Publisher: Springer Science and Business Media LLC

Date: 21-07-2022

DOI: 10.1007/S13592-022-00936-3

Abstract: Two stingless bee species, Tetragonula carbonaria and Tetragonula hockingsi , engage in extreme inter-colony fights, both within and between species. Inter species fights can result in one species taking over the nest of the other. Following successful takeovers, brood from the previous colony could be retained and become workers, but this has yet to be tested. We first tested whether T. carbonaria callows are accepted when introduced into a different conspecific nest and found that they are indeed accepted as normal workers. This suggested that mixed species cohorts might be expected after a hive takeover. We assessed this in a managed T. carbonaria hive, fitted with an observation window that was subject to multiple takeover attempts. Using microsatellite genotyping, we established that multiple different colonies (of both species) attacked the observation colony over 63 days, resulting in a catastrophic collapse of the nest. Our observations inside the hive during these inter-colony invasions revealed no evidence of resource robbing, adding further support to the hypothesis that fighting behaviour in these species has the primary goal of taking over the nest. Newly emerged callows were ejected by invaders, predominantly during the initial few days of fighting. The ejection of callows ceased however, shortly after each takeover attempt, and, following this, newly emerged callows were accepted as workers. These findings add new evidence that the invading colony co-exists with workers from the previous brood following a takeover, but only until the last of that cohort dies.

Differential temperature responses between Plutella xylostella and its specialist endo‐larval parasitoid Diadegma semiclausum—Implications for biological control

Publisher: Wiley

Date: 11-10-2022

DOI: 10.1111/1744-7917.12967

Abstract: Understanding the thermal dynamics of host–parasitoid interactions is crucial to predicting how biological control of pest insects by parasitoids might be affected by geographic location and climate change. We compared performance traits of Plutella xylostella (Lepidoptera: Plutellidae) and its solitary endo‐larval parasitoid Diadegma semiclausum (Hymenoptera: Ichneumonidae), over a wide range of constant rearing temperatures (10–30°C). Parasitoids reared at 30°C experienced reductions in pupation rate, pupal mass, egg load, and adult life span when compared with those reared at lower temperatures. Our analyses of the fate of parasitoids and their hosts and intergenerational population growth at different rearing temperatures show that D. semiclausum and P. xylostella respond differently to temperature, leading to ergent outcomes under different temperature conditions. Some parasitoid larvae could not complete development at 30°C, the temperature at which the host biomass was least and the metabolic demands of the parasitoid could be high, suggesting that parasitoid development might be constrained by lack of host resources at higher temperatures. We discuss the potential mechanisms of parasitoid susceptibility to elevated temperatures, which likely explain the pronounced seasonal dynamics of D. semiclausum in subtropical regions and its failure to establish in lowland tropical regions, where P. xylostella is a serious pest. Similar interactions in other host–parasitoid associations would constrain the efficacy of parasitoids as biological control agents as global temperatures increase.

A true desert falcon with a delayed onset of heat dissipation behaviour

Publisher: Elsevier BV

Date: 07-2021

DOI: 10.1016/J.JARIDENV.2021.104530

Linkage Projects - Grant ID: LP0212073

Start Date: 2002

End Date: 03-2006

Amount: $67,635.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP1095482

Start Date: 2010

End Date: 02-2014

Amount: $120,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP160102806

Start Date: 2016

End Date: 10-2019

Amount: $388,800.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP130103858

Start Date: 2013

End Date: 12-2016

Amount: $400,000.00

Funder: Australian Research Council

Special Research Initiatives - Grant ID: SR0354908

Start Date: 2004

End Date: 12-2004

Amount: $10,000.00

Funder: Australian Research Council