Research

Beltwide 2023

13Jan

I gave a talk on my work with cotton fleahoppers at the Beltwide Cotton Conferences 2023 (Jan 10-12; New Orleans, LA), entitled “Effect of Moisture Treatment on Cotton Fleahopper Nymph Emergence from Woolly Croton”. Pictured at the conference with fellow graduate student Max Sturdivant (from Dr. Isakeit’s lab, PLPM), and former BESC student, Alexandra Crowder. Picture taken by Dr. Chappell, who also gave a talk at the conference, entitled “Interaction between Pathogenic and Saprophytic Growth of Fusarium oxysporum f. sp. vasinfectum“.

DIY EPG

26Aug

We received good news that Manjari requires more space for her EPG work, so the group made another Faraday cage.

Modeling thermoregulators

18May

Working with Aaron Tarone of Texas A&M Entomology and members of his group, we have been developing insect phenology models that account for thermoregulatory behavior. These models are intended for use in predicting vector and pest dynamics, and in retrodicting events of forensic importance that can be indicated by insect development.

We’re happy to have some of this work recently published in Frontiers in Ecology and Evolution: https://static.frontiersin.org/articles/10.3389/fevo.2022.837732/full

The rationale of this work has been that organisms capable of behavior will behave in ways that are on average beneficial. Insects have been shown to “have” what we call “preferred temperatures.” The mechanisms related to this are complex, but they don’t need to be clarified before we can improve predictions by implicitly incorporating behavior into models. Our improvement transforms distributions of environmental temperature into distributions of insect temperatures, through a function that involves environmental temperature and its variance, and insect preferred temperature. It is a simple convolution, wherein development rate is a function of insect body temperature, which is a function of environmental temperatures and insect behavior.

Here’s how it looks:

The graph shows temperatures through time: ambient air (which is what many phenology models use as input), colonized flesh (because this work was done on necrophagous fly larvae), and predicted insect temperature using our model. I’ve arbitrarily chosen 27 °C as a preferred temperature. Blue bands around the ambient temperature trace are to suggest temperature variation across space. Predicted larval temperatures lie between ambient and preferred, determined jointly by the difference between ambient and preferred and the variance around ambient.

Roy’s soilborne inoculum work

5May

Roy spent plenty of time in the laboratory quantifying Fusarium oxysporum f. sp. vasinfectum (Fov) DNA from field soil, and some of his work is now reported in a Plant Disease publication: https://doi.org/10.1094/PDIS-08-21-1664-RE

The work’s objective was to describe spatial variability in Fov inoculum density in the field, because that variation is hypothesized to affect risk of cotton plants expressing Fusarium wilt disease. Much of Roy’s report concerns development of the quantification method, which targets the Fov race affecting the selected field sites. Roy discovered that inoculum density varies across the field space by orders of magnitude (shown in the figure below, where “inoculum level” is a relative logarithmic scale), and by observing it at multiple time points he noticed a temporal pattern: inoculum density trajectory depends on growth resource type and availability, which depends on prior inoculum density. Roy is now finishing documentation of that cycle in this system.