Insect Social Behavior and Evolution: Research in our lab centers on the behavior, ecology, and evolution of social insects, with an emphasis on termites. Termites (Order Blattodea) evolved eusociality 50 million years earlier than social species in Hymenoptera (ants, bees, wasps), and they are a classical and important group for understanding the evolution of eusociality. We apply integrative approaches combining perspectives from chemical ecology, neurobiology and genetics. Big questions of interest include:
Urban Entomology: We are also interested in the biology and management of insects associated with urban environments, with the goals of understanding various factors affecting household and structural pests, and developing tools for their control.
- What are the social cues in behavioral and developmental modulation?
- What are the olfactory mechanisms in perception and processing of social information?
- How do pheromone, behavior, and regulatory mechanisms evolve in the cockroach-termite lineage?
Urban Entomology: We are also interested in the biology and management of insects associated with urban environments, with the goals of understanding various factors affecting household and structural pests, and developing tools for their control.
CURRENT PROJECTS
Termite Chemosensation
Social evolution is integrated with the evolution of chemical communication, which is the oldest and the primary form of communications and plays an essential role in regulating fundamental behaviors. However, little is known about how chemicals are perceived in the peripheral sensory system and how chemosensory information is processed in the brain of termites. We integrate neuroanatomic and transcriptomic approaches to characterize the chemosensory system in termites, including illustration of antennal sensilla and brain organization in different castes, and investigation of the spatial-temporal expression of chemosensory related genes.
Genetics and Genomics
We are sequencing the genome of the Formosan subterranean termite, and collaborating on the genome sequencing projects of several other termites and cockroaches. We will use these resources to develop functional genetic approaches to study the molecular underpinnings of social behavior and invasion biology of the Formosan subterranean termite, and explore the evolution of sociality in the cockroach-termite lineage.
Invasion Biology of the Formosan Subterranean Termite
The Formosan subterranean termite, Coptotermes formosanus, is an invasive species to the United States and the most destructive termite in the world. In addition to transportation via human activities, the successful invasion and spreading of this termite is largely due to a number of distinct social activities and superior competitive capabilities compared with the native species. We explore the biological signatures contributing to its invasion, and investigate environmental factors affecting distribution and dispersal of termites.
Stored Rice IPM (with Blake Wilson)
We are collaborating with the Wilson Lab on the development of best management practices for insect pests of stored rice. This research will provide information for reducing impact of stored grain pests to the Louisiana rice industry by identifying more effective and efficient controls.
Social evolution is integrated with the evolution of chemical communication, which is the oldest and the primary form of communications and plays an essential role in regulating fundamental behaviors. However, little is known about how chemicals are perceived in the peripheral sensory system and how chemosensory information is processed in the brain of termites. We integrate neuroanatomic and transcriptomic approaches to characterize the chemosensory system in termites, including illustration of antennal sensilla and brain organization in different castes, and investigation of the spatial-temporal expression of chemosensory related genes.
Genetics and Genomics
We are sequencing the genome of the Formosan subterranean termite, and collaborating on the genome sequencing projects of several other termites and cockroaches. We will use these resources to develop functional genetic approaches to study the molecular underpinnings of social behavior and invasion biology of the Formosan subterranean termite, and explore the evolution of sociality in the cockroach-termite lineage.
Invasion Biology of the Formosan Subterranean Termite
The Formosan subterranean termite, Coptotermes formosanus, is an invasive species to the United States and the most destructive termite in the world. In addition to transportation via human activities, the successful invasion and spreading of this termite is largely due to a number of distinct social activities and superior competitive capabilities compared with the native species. We explore the biological signatures contributing to its invasion, and investigate environmental factors affecting distribution and dispersal of termites.
Stored Rice IPM (with Blake Wilson)
We are collaborating with the Wilson Lab on the development of best management practices for insect pests of stored rice. This research will provide information for reducing impact of stored grain pests to the Louisiana rice industry by identifying more effective and efficient controls.
RESEARCH PROJECTS PRIOR TO LSU
Undertaking behavior
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Cannibalism or burial
Undertaking behavior, the disposal of dead colony members, is a stereotypic behavior in many social insects to prevent potential pathogenic attack. Ants and honey bees carry deceased members out of the nest, but termites that feed on nitrogen-limited woody diet could benefit from recycling rather than discarding nutrients from dead nestmates. My Ph.D. research demonstrated that termites alternatively cannibalize or bury corpses based on their origin and postmortem time. They retrieve and consume freshly dead conspecifics, but bury corpses of competitive species. In addition, termites bury dead conspecifics if they are highly decomposed. Combined results from behavioral observations and brain transcriptomic profiling indicate that cannibalism is not only nutritionally beneficial, but also more energetically efficient than burial. (Watch YouTube movies for how termites manage corpses of different origins and postmortem times, and see a poster for transcriptomic analysis.) |
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Death cue
The exploration of death cues in social insects was pioneered by E. O. Wilson in 1958. Since then, postmortem accumulation of fatty acids has been demonstrated to trigger corpse removal in several ants. As a part of my Ph.D., I identified the dynamic changes of death cues in termites. Immediately after death, the corpse releases a blend of volatiles, 3-octanone and 3-octanol, which attract live workers to retrieve and consume the bodies. The early death cue decreases quickly as the corpse decomposes. Correspondingly, the accumulation of late death cues (fatty acids, phenol, indole) elicits a behavioral switch from cannibalism to burial. The dynamic change in death cues balances nutritional rewards and pathogenic risks. This postmortem chemical communication highlights unique adaptations in termites to their ecological and social niche. |
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Worker-reproductive transition
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Reproductive pheromones In social organisms, individual development exhibits strong plasticity depending on the social environment. In many termite species including R. flavipes, workers are reproductively totipotent. They can differentiate into ergatoid reproductives, and continue reproduction after the death of primary queen and king. Reproductive pheromones that inhibit worker-reproductive transition have been suggested, but my study showed exciting results with evidences of both inhibitory and stimulatory substances influencing ergatoid formation. Potential sources and types of these pheromones (e.g., proctodeal fluid, cuticular hydrocarbons, and volatile substances) have been examined. This research will improve our understanding of reproductive division of labor in termites, one of the few hemimetabolous eusocial insects with bisexual colonies. |
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Policing behavior
Reproductive conflict widely occurs in eusocial species where workers are reproductively totipotent. It is particularly true in termites during the process of reproductive succession, as conflict arises when the number of ergatoids exceeds the limit that colony can sustain. Termites resolve the conflict by killing excessive ergatoids, a previously poorly studied behavior. We addressed several questions including who kill the ergatoids, whether the attack is sex-specific, and whether it is age-dependent. Observations and experiments showed that policing behavior in R. flavipes is a concerted effort carried out by both ergatoids and workers, and the policing by ergatoids is age-dependent. Specially, older ergatoids attack younger ones, and workers are then recruited to cannibalize the injured ergatoids. This study provides the first empirical evidence of policing behavior in termites. |
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Before becoming a social insect enthusiast, I studied earthworm diversity when I was a Master’s student, and Maillard reaction when I was an undergraduate at China Agricultural University in Beijing.
