Myrmeleontiformia, an ancient and fascinating group of lacewing insects, includes species such as antlions and their relatives. These insects are known for their remarkable predatory larvae, which exhibit unique morphologies and behaviors. A recent study led by Professor Wang Bo from the Chinese Academy of Sciences (NIGPAS), in collaboration with two Italian researchers, has made significant discoveries about the evolution and behaviors of Myrmeleontiformia through the study of fossilized specimens found in Burmese amber. The research, published in Nature Communications on August 22, 2018, provides new insights into the ecological roles and survival strategies of these ancient insects, some of which date back approximately 100 million years to the mid-Cretaceous period.
The primary findings from this study challenge the conventional understanding of the evolution of Myrmeleontiformia. One of the most striking revelations is that, despite the passage of over 100 million years, Myrmeleontiformia did not undergo significant morphological changes. Rather, the diversity observed within this group seems to have arisen from the combination of a limited set of traits in what appears to be a complex trade-off. This phenomenon, referred to as morphological stasis, is not uncommon in evolutionary biology, but it is particularly interesting when applied to these ancient insects.
The study’s authors employed sophisticated statistical correlation analyses to investigate how certain morphological features in Myrmeleontiformia related to their hunting strategies. Myrmeleontiformia, known for their ambush predation tactics, exhibited two primary strategies: camouflaging and fossoriality (burrowing). These behaviors are crucial for their success as predators, as they allow the larvae to remain concealed and strike unexpectedly when potential prey ventures too close.
The analysis strongly supports the idea that specific morphological traits were linked to these two strategies. For example, the presence of certain elongate protuberances in the larvae’s bodies was statistically correlated with camouflaging behavior. The larvae would often cover themselves in debris such as sand or plant matter to blend into their surroundings, a strategy that allowed them to avoid detection by both prey and predators. The strong correlation between these protuberances and camouflaging behavior suggests that this trait could serve as an indicator of such behavior, even when the debris used for camouflage was not preserved in the amber fossils. This discovery has important implications for understanding the lifestyle and ecological roles of these ancient insects.
Moreover, the study indicated that fossorial specialization, a behavior characterized by burrowing and ambushing prey from below, evolved more than once within Myrmeleontiformia. Fossoriality is a significant factor in the evolutionary success of antlions and their relatives. By developing the ability to burrow, these insects were able to exploit habitats that were often inhospitable to other species, particularly arid environments where the ability to survive extreme temperature fluctuations and dry conditions was crucial. This adaptation not only helped these insects survive during periods of environmental change, but it also enabled them to diversify in these harsh terrestrial landscapes during the Cretaceous period.
The Burmese amber fossils, which were crucial to this study, showed that these camouflaging behaviors were characteristic of the lineage for at least 100 million years. The fossils contained larvae that displayed various forms of camouflage, with some covered in debris, while others exhibited the protuberances that likely aided in their concealment. The fact that this behavior persisted so long into the evolutionary history of Myrmeleontiformia demonstrates the effectiveness and importance of this hunting strategy.
This research also suggests that camouflaging behavior did not arise in a single lineage but evolved independently at least three times within the Myrmeleontiformia group. This repeated evolution of camouflaging tactics across different lineages highlights the adaptive significance of this behavior. Whether it was through debris covering or other means, camouflaging allowed the predatory larvae to hide from unsuspecting prey, increasing their chances of survival and successful predation.
The combination of fossoriality and camouflaging behavior appears to be widespread across the lineage of Myrmeleontiformia. Both strategies were highly effective in helping these insects secure food and avoid being detected by predators. These behaviors also reveal how these ancient lacewing insects were able to adapt to and thrive in their respective environments, demonstrating the critical role of predation strategies in their evolutionary history.
In addition to the biological significance of these findings, the study provides a glimpse into the broader ecological context of the Cretaceous period. Fossils preserved in amber often capture a snapshot of ancient ecosystems, allowing scientists to infer not only the characteristics of individual species but also the interactions between different organisms. The preservation of Myrmeleontiformia larvae in Burmese amber gives us a rare and invaluable look into the lives of these ancient predators, revealing how they interacted with their environment and what made them successful over millions of years.
The study led by Professor Wang Bo and his colleagues has provided new insights into the evolutionary history and ecological niches of Myrmeleontiformia. By using advanced statistical analysis to link morphology with behavior, the researchers were able to reconstruct the hunting strategies and lifestyles of these ancient insects. The findings shed light on the adaptive strategies that allowed Myrmeleontiformia to survive and thrive in changing environments and how these strategies influenced their evolutionary success. The persistence of certain morphological traits, such as elongate protuberances and debris covering, underscores the importance of these behaviors in the survival of Myrmeleontiformia over an extended period of time.
This research also raises intriguing questions about the potential for other ancient species to have undergone similar evolutionary patterns. The concept of morphological stasis and the repeated evolution of certain behaviors could be applicable to other insect groups or even to species outside of the insect kingdom. By studying these ancient predators, scientists gain a deeper understanding of the complex interplay between morphology, behavior, and survival in the evolutionary process.
The work done by Professor Wang and his international team represents a significant step forward in our understanding of Myrmeleontiformia and the broader evolutionary history of lacewing insects. Their research offers valuable insights not only into the past but also into how we might approach the study of other ancient species, providing a more comprehensive picture of life on Earth millions of years ago.
More information: Davide Badano et al, Diverse Cretaceous larvae reveal the evolutionary and behavioural history of antlions and lacewings, Nature Communications (2018). DOI: 10.1038/s41467-018-05484-y