Research projects

From field observations and controlled experiments to sequencing and code, I study insects and their parasites whose evolutionary histories are intertwined with ours.

Original Dr. Jekyll and Mr. Hyde illustration comparing a green solitary grasshopper with a yellow and black gregarious locust.

Illustrated life cycle of a locust swarm connecting population density, behavior, physiology, molecular regulation, swarming, and population decline.

01 / ACTIVE FLAGSHIP QUEST

Density-dependent behavioral plasticity and locust swarming

What are the earliest gene-regulatory events that initiate the locust phase transition?

Do Schistocerca locusts share an ancestral molecular “master switch,” or has evolution followed different routes to swarming?

My research uses controlled density manipulation across multiple Schistocerca species with different degrees of locust phase plasticity. In particular, I follow phase transitions within individuals from their earliest molecular signals (a few hours) to visible changes in behavior, morphology, and physiology (a few days). Working collaboratively, we established standardized multi-species rearing, behavioral assays, and experimental transfers between isolated and crowded conditions to induce gregarization and solitarization in the TAMU locust quarantine. I led the time-sensitive dissections and bulk tissue processing in the wet lab for RNA sequencing. Together, our BPRI team generated approximately 500 time-resolved transcriptomes per species and integrated these data with six chromosome-scale genomes, comparative genomics, behavioral measurements, and functional RNAi experiments.

This comparative phylogenetic framework tests whether repeated swarming evolved through a conserved regulatory core or through partly distinct molecular solutions in each lineage. Our comparative results support multiple routes to swarming despite highly conserved genomes and reveal substantial variation in gene expression responses among species, tissues, and even individuals.

Varroa destructor host-shift reconstruction showing an inferred population jump from Asian to western honey bees.

World map showing the broad geographic distribution of the international Varroa sampling collection, with regions distinguished by color.

02 / GLOBAL PARASITE QUEST

Varroa evolution and global invasion

How does a serially bottlenecked global invader persist despite intensive control, and how does it continue to evolve over a century?

Varroa mites provide a rare opportunity to study a host shift and global invasion unfolding over only a few decades. Despite severe genetic bottlenecks during the host switch from the eastern honey bee, Apis cerana, to the western honey bee, A. mellifera, and further bottlenecks during expansion into new countries and islands, V. destructor has persisted for nearly a century and repeatedly evolved resistance to acaricides. Together with the viruses it vectors, the mite is a major contributor to honey bee colony losses worldwide.

I developed methods to sequence DNA and RNA from individual mites preserved in ethanol. With collaborators, we generated genomic resources, reconstructed the invasion's early demographic history, and connected mite movement with the evolutionary history of deformed wing viruses. Since 2016, I have built a collaborative network spanning 61 countries. I am now integrating a global collection sampled across more than three decades, including over 1,700 sequenced mite genomes. Evolutionary genomics can reveal diversity hidden by the mites' nearly indistinguishable appearance to inform bee-health surveillance and sustainable control in a globalization era.

Map of honey bee sampling locations and mitochondrial lineage proportions across Europe, Africa, and southwest Indian Ocean islands.

03 / ORIGIN CHAPTER

Island honey bee biogeography and conservation

How do natural colonization and human introductions combine to shape island biodiversity?

Island honey bees were my first system for investigating how evolutionary history becomes recorded in DNA. Working with beekeepers and regional partners, I used mitochondrial markers and nuclear microsatellites to distinguish older colonization and geographical isolation from recent introductions and admixture across the southwest Indian Ocean. This work revealed strongly differentiated island populations and a distinctive regional lineage related to the Malagasy honey bee Apis mellifera unicolor. Beyond reconstructing history, the results helped establish a scientific basis for recognizing native island honey bee diversity and informed discussions around conservation, importation, and biosecurity. This foundational research continues to shape how I think about genetic diversity, connectivity, and human influence in all my study systems.