Biology subjects

Tregenza, T.

Publications and source records attributed to Tregenza, T..

9 recordsLinked to original sources

bioRxiv2026

Deep learning reveals the individual-level effects of artificial light at night on a wild insect

Artificial light at night (ALAN) is a widespread anthropogenic phenomenon with varied physiological, behavioural, and ecosystem-level effects. Its impacts have been studied extensively at the population level, however less is known about the individual changes that underpin these larger trends. We use a networked video system combined with GryllAI--a deep learning-based system for continuous individual monitoring--to explore this in the field cricket, Gryllus campestris. Applying field-realistic artificial light (10-25lx) or a control treatment to burrows, we continuously track the activity of 144 nymphs across >38,000h of video footage, recording life history outcomes for each individual. Results indicate that ALAN exposure does not influence daily activity timing, total activity duration, predation risk, or nymphal development duration. However, changes in fine-scale behaviour were apparent, with ALAN causing crickets to enter and exit burrows less frequently, especially at night; and spent greater proportion of time outside burrows during daytime. These behavioural adjustments were not evident from broad scale activity trends that could be observed manually. Consequently, our findings suggest that aggregate measures of activity may fail to capture the full scope of ALAN-mediated impacts in nature, and that automated monitoring techniques offer a promising means of addressing this.

ecology↗

bioRxiv2026

Exploring the ageing and survival costs of investment in anti-predation responses in a wild insect?

Escape behaviour directly influences survival, yet individuals often vary substantially in escape performance. Laboratory studies have documented trade-offs between anti-predator responses and life-history traits, but it remains unclear whether such trade-offs occur under natural predation risk. We studied a natural population of the field cricket Gryllus campestris. Mortality risk and behavioural performance are known to change with age in this species. We aimed to determine whether individuals expressing a higher escape response pay a cost in terms of a faster increase in mortality risk with age or a shorter lifespan. We quantified escape speed in response to a vibrational predation cue. We found no clear evidence for a trade-off between escape performance and lifespan or age-specific mortality risk. The relationship between escape speed and the among-individual effect of age differed between sexes: older males showed faster escape speeds compared with younger males, whereas younger females were faster than older females. This pattern is consistent with sex-specific selective disappearance. Individual baseline mortality risk varied with sex and escape speed, but age-dependent mortality did not. It suggests that such trade-offs in the wild may be context- or condition-dependent rather than reflecting a universal life-history trade-off.

animal behavior and cognition↗

bioRxiv2026

Parental age at reproduction accelerates offspring pace of life in Gryllus bimaculatus

Across invertebrates, it is widely known that older parents produce offspring with abbreviated lifespans (i.e., the Lansing effect). Yet the ecological and evolutionary ramifications of such nongenetic parental age effects remain unclear. Two demographic processes could culminate in a Lansing effect, with different fitness implications: (i) Later-conceived offspring may display greater mortality from conception, constraining fitness from birth. (ii) Alternatively, they may exhibit an increased age-specific mortality (i.e., accelerated senescence), with negative effects that manifest after maturity. If parental age accelerates offspring senescence without affecting initial mortality rate, then later-conceived offspring may maintain fitness by shifting to a faster pace-of-life. We exposed Gryllus bimaculatus parents to one of three experimental temperatures to generate environmental variation in parent mortality. Using a longitudinal within-parent study, we tested whether parental age influenced offspring longevity via increased initial mortality or accelerated senescence, and whether these effects depended on the parents thermal environment. Contrary to our predictions, we found no evidence that parental age reduced offspring longevity. Instead, parental age mediated offspring pace-of-life. Irrespective of the parents thermal environment, the earliest- and latest-conceived offspring were demographically distinct. Later-conceived offspring exhibited accelerated development, a smaller adult mass, and improved reproductive success. Unexpectedly, they also showed extended adult lifespans. This increased adult lifespan did not arise from reduced initial mortality, but from a delayed onset and slower progression of actuarial senescence. The slowed senescence in later-conceived offspring is unlikely to reflect a direct parental age effect, potentially arising indirectly through causal effects on adult size. Our results challenge the universality of the Lansing effect and contribute to a growing recognition that parental age has important life-history consequences. Accelerated life-histories in later-conceived offspring may be adaptive, enabling these individuals to compete over dwindling seasonal resources or overcome seasonal time constraints. Determining whether these demographic parental age effects accumulate across generations, or persist under natural environments, will be essential for establishing their ecological consequences and proximate role in the evolution of ageing. Open research statementData and code are not yet provided but will be made openly and freely available on request during the review process. Data will be uploaded to the Dryad data repository and code will be uploaded to Zenodo open repository on acceptance of the manuscript.

evolutionary biology↗

bioRxiv2026

Sublethal exposure to the insecticide chlorantraniliprole does not alter antipredator behaviour in wild field crickets

Pesticide exposure has been proposed as a major driver of global insect declines. Sublethal effects occur when non-fatal pesticide exposure disrupts behaviour or physiology in ways that may reduce survival or reproductive success. However, most evidence for sublethal effects comes from laboratory studies under controlled conditions. We tested whether exposure to a sublethal dose of chlorantraniliprole, a widely used diamide insecticide known for its long environmental persistence, affects antipredator escape behaviours in wild field crickets (Gryllus campestris). Adult crickets were treated with either pesticide or a sham control. They then underwent behavioural tests in the wild. Following a simulated predator attack, we measured two key behaviours: escape speed and subsequent latency to re-emerge from their burrow. We found no consistent effects of pesticide exposure on either behaviour. Re-emergence latency increased over successive days across both groups, while escape speed did not change. Re-emergence latency showed greater individual variability than escape speed. This likely reflects its role as a risk-assessment behaviour, which is more context-dependent than escape speed. Our findings challenge the assumption, largely derived from laboratory assays, that sublethal pesticide exposure universally impairs insect behaviour. Overall, our results underscore the need to integrate environmental context when evaluating pesticide impacts on insect behaviour.

animal behavior and cognition↗

bioRxiv2025

Testing for pre- and post-copulatory inbreeding avoidance in the flour beetle Tribolium castaneum

Inbreeding depression poses a significant threat to fitness in many taxonomic groups, particularly those where close relatives are likely to come into contact. Studies have suggested that females may mate with multiple males to reduce inbreeding through post-copulatory processes of closely related males. In our mating trials, we examine potential pre- and post-copulatory inbreeding avoidance in the red flour beetle Tribolium castaneum using behavioural observations and subsequently, through the use of phenotypic mutant markers to assign parentage. As expected, mating rates were largely limited by females. Contrary to expectations, males courted and mated with related females more frequently than with unrelated females. Unrelated males sired a greater proportion of the offspring of doubly mated females, but this was explained by the higher survival of their offspring to adulthood. When the lower survival of inbred offspring was accounted for, there was no difference in the estimated fertilisation success of related and unrelated females. We show that last male sperm precedence declined over 5 weeks, suggesting that the cause of sperm precedence was primarily displacement of previously stored sperm, with evidence for a limited degree of sperm stratification within the spermatheca.

evolutionary biology↗

bioRxiv2025

Trait-specific responses to repeated stressor exposure in wild crickets

Habituation allows animals to reduce their responsiveness to repeated, non-threatening stimuli. While well-studied in vertebrates, little is known about how wild insects adjust their behaviour to repeated stressors in natural settings. This study tested whether wild field crickets (Gryllus campestris) habituate or sensitise to repeated simulated predator attacks, and whether these effects vary with threat intensity. Crickets showed limited evidence of habituation. Emergence time increased slightly over repeated exposures, consistent with modest sensitisation, while post-emergence distance also increased, suggesting a modest habituation effect. Escape speed remained stable. Our results suggest trait-specific behavioural plasticity, as only some response measures changed across repeated exposures while others remained stable. Crickets ranged further from the burrow in response to the stronger stimulus, suggesting greater comfort or reduced perceived risk, though emergence latency and escape speed were unaffected by stimulus intensity. Contrary to our predictions, individual crickets did not respond consistently across the two stimulus types. While some increased their emergence time or post-emergence distance more under one stimulus than the other, others showed little or no change. These patterns suggest that only certain behaviours were flexible, and that individuals varied in how strongly they adjusted these behaviours. Escape speed, by contrast, remained stable. Together, these results indicate limited habituation, trait-specific flexibility, and substantial individual variation in how crickets respond to repeated disturbance, highlighting the diverse strategies animals may use to manage risk in unpredictable environments.

animal behavior and cognition↗

bioRxiv2024

How air temperature and solar radiation impact life history traits in a wild insect

Ectotherms are essential components of all ecosystems and rely on external heat to regulate their body temperature. For most terrestrial ectotherms the primary sources of heat are ambient temperature and solar radiation. Many insects can use movement to respond to changes in temperature and solar radiation in order to manage their body temperature and optimise life history traits. However, we lack the understanding of the relative importance of temperature and shade that we need to predict how the combined effects of changes in air temperature and cloud cover will impact terrestrial insect populations. We reared developing nymphs of the field cricket (Gryllus campestris) at high and low air temperature sites with partially shaded and unshaded treatments at each site. Given the broad altitudinal range of this species, we tested the possibility of local adaptation to these climate variables by rearing nymphs from high and low altitude genetic lineages in all treatment combinations. We found that development time was strongly affected by air temperature, but not by a substantial increase in shade. This suggests that developing crickets can compensate for an increase in shade, presumably because in unshaded conditions they forgo some opportunities to gain energy from the sun. We found that mass at adulthood was affected by an interaction between availability of sun (shading treatment) and air temperature. This indicates that changes in cloud cover will impact insects differently in warmer and cooler areas. We found no evidence for local adaptation in these traits. Our findings underscore the need to consider both ambient temperature and solar radiation in predicting the impacts of climate change on insect populations, as shifts in temperature and cloud cover may have complex and region-specific effects on these vital ecosystem components.

evolutionary biology↗

bioRxiv2020

Telomere length is highly heritable and independent of growth rate manipulated by temperature in field crickets

Many organisms are capable of growing faster than they do. Restrained growth rate has functionally been explained by negative effects on lifespan of accelerated growth. However, the underlying mechanisms remain elusive. Telomere attrition has been proposed as a causal agent and has been studied in endothermic vertebrates. We established that telomeres exist as chromosomal-ends in a model insect, the field cricket, using terminal restriction fragment and Bal 31 methods. Telomeres comprised TTAGGn repeats of 38kb on average, more than four times longer than the telomeres of human infants. Bal 31 assays confirmed that telomeric repeats were located at the chromosome-ends. We tested whether rapid growth is achieved at the expense of telomere length by comparing crickets reared at 23°C with their siblings reared at 28°C, which grew three times faster. Surprisingly, neither temperature treatment nor age affected average telomere length. Concomitantly, the broad sense heritability of telomere length was remarkably high at ~100%. Despite high heritability, the evolvability (a mean standardized measure of genetic variance) was low relative to that of body mass. We discuss the different interpretations of these scaling methods in the context of telomere evolution. It is clear that some important features of vertebrate telomere biology are evident in an insect species dating back to the Triassic, but also that there are some striking differences. The apparent lack of an effect of growth rate and the total number of cell divisions on telomere length is puzzling, suggesting that telomere length could be actively maintained during the growth phase. Whether such maintenance of telomere length is adaptive remains elusive and requires further study investigating the links with fitness in the wild.Competing Interest StatementThe authors have declared no competing interest.View Full Text

zoology↗

bioRxiv2018

Dynamic networks of fighting and mating in a wild cricket population

Reproductive success is often highly skewed in animal populations. Yet the processes leading to this are not always clear. Similarly, connections in animal social networks are often non-randomly distributed, with some individuals with many connections and others with few, yet whether there are simple explanations for this pattern has not been determined. Numerous social interactions involve dyads embedded within a wider network. As a result, it may be possible to model which individuals accumulate social interaction through a more general understanding of the social networks structure, and how this structure changes over time. We analysed fighting and mating interactions across the breeding season in a population of wild field crickets under surveillance from a network of video cameras. We fitted stochastic actor-oriented models to determine the dynamic process by which networks of cricket fighting and mating interactions form, and how they co-influence each other. We found crickets tended to fight those in close spatial proximity to them, and those possessing a mutual connection in the fighting network, and heavier crickets fought more often. We also found that crickets who mate with many others tended to fight less in the following time period. This demonstrates that a mixture of spatial constraints, characteristics of individuals and characteristics of the immediate social environment are key for determining social interactions. The mating interaction network required very few parameters to understand its growth and so structure; only homophily by mating success was required to simulate the skew of mating interactions seen in this population. This demonstrates that relatively simple, but dynamic processes can give highly skewed distributions of mating success.

animal behavior and cognition↗