Studio comportamentale degli effetti delle heatwave sulla socialità in Gromphadorhina portentosa

Climate change has led to a significant increase in global temperatures and a higher frequency of extreme events such as heatwaves. These phenomena have a substantial impact on biodiversity, affecting numerous animal species with both lethal and sublethal consequences. Heatwaves not only cause direct mortality in various species, such as coral bleaching and the death of vertebrates and invertebrates, but also produce sublethal effects that compromise essential biological aspects, including fertility, cognitive development, and social behavior. This study investigated the effects of simulated heatwaves on Gromphadorhina portentosa, a species of cockroach, to understand the impact of such events on body weight and social dynamics. Experimental groups, consisting of three males and three females, were exposed to a simulated heatwave treatment, while control groups were maintained under standard conditions. Individuals were monitored for five days before and after exposure to the treatment, using camera traps to record social and territorial interactions. Behaviors were coded using BORIS software. Exposure to heatwaves resulted in a significant reduction in body weight among treated individuals. Males experienced a greater loss of weight compared to females, suggesting a possible sex-specific vulnerability to thermal treatment. Pre-treatment behavioral analysis revealed that males more frequently occupied the dominant position above the refuge, an indicator of social hierarchy. However, post-treatment, this tendency was significantly reduced in the treated group, while it remained stable in the control group. Conversely, females showed a temporary increase in the use of elevated positions in the 24 hours following heatwave exposure, indicating an acute stress response. Despite the initial increase, female behavior returned to pre-treatment levels in the following days, suggesting a rapid adaptation to thermal exposure. Social hierarchy analysis showed that four groups out of eight demonstrated a correlation between horn size and dominant position, with males with larger horns tending to occupy higher positions. However, not all groups followed this trend, suggesting that other factors, such as individual experience or additional behavioral traits, might influence hierarchical dynamics. The observed variability between groups indicates the presence of alternative strategies in dominance competition, where horn size is not necessarily the predominant factor. The lack of a univocal relationship between horn size and aggressiveness underscores the need for a more thorough evaluation of social interactions under thermal stress conditions. The results indicate that heatwaves have significant effects on both metabolism and behavior, with differences between males and females in response to the treatment. Males experienced a more pronounced weight loss and a decrease in dominant position occupancy post-treatment, suggesting greater sensitivity to heat. Females, while not experiencing the same impact on weight, showed a transient but significant behavioral response

Il cambiamento climatico ha provocato un aumento delle temperature globali e una maggiore frequenza di eventi estremi come le ondate di calore, che hanno un impatto significativo sulla biodiversità. Questo studio ha analizzato gli effetti delle ondate di calore simulate su Gromphadorhina portentosa, una specie di blatta, per comprendere l’impatto su peso corporeo e dinamiche sociali. Gli esemplari, allevati a Padova, sono stati divisi in gruppi sperimentali e di controllo, esposti a trattamento termico o mantenuti in condizioni normali. I comportamenti sono stati monitorati e analizzati. L’esposizione ha portato a una significativa riduzione del peso corporeo, con i maschi che hanno mostrato una perdita maggiore rispetto alle femmine. La tendenza di occupare posizioni rialzate da parte dei maschi del gruppo di controllo è diminuita in seguita al trattamento, mentre per i maschi del gruppo di controllo si è mantenuta regolare. L'analisi della gerarchia sociale ha mostrato una correlazione tra dimensione delle corna e posizione dominante, con i maschi con corna più grandi che tendevano a occupare posizioni superiori, sebbene non in tutti i gruppi. Questo suggerisce che la dimensione delle corna non è l’unico fattore influente. I risultati indicano che le ondate di calore hanno effetti significativi su metabolismo e comportamento, con differenze di risposta tra maschi e femmine.