INSECT PHYSIOLOGY
This research was conducted at Dr. Bryony Bonning's group at the Entomology and Nematology Department of the University of Florida. It was financed by CAMTech, an Industry/University research collaboration center, to investigate the digestive physiology of the southern green stink bug, Nezara viridula (Hemiptera:Pentatomidae).
Once considered secondary pests in fields, stink bugs have increased in importance in recent years as pests of several crops of high agricultural value, such as soybean, corn and cotton. Changes in agricultural practice, changing climate, and reduced use of chemical insecticides have contributed to this problem. Few alternatives to broad spectrum chemicals exist to counter stink bug populations, which highlights the need to develop novel and ecologically sound strategies. With this mind, our research looked to identify tissue and diet specific targets that may later be used as targets for biotechnological control methodologies. |
Tissue specific activities
The midgut of species of Pentatomidae is divided into 4 distinct anatomical regions. The first three are thought to be involved in digestion, while the most posterior region appears to have little enzymatic activity related to degradation of dietary compounds. However, in stink bugs it was unclear which digestive activities occurred in each compartment, and it was not explored in detail in Nezara viridula.
In this research, I analyzed the activity of proteases and nucleases in each of the digestive regions on the midgut, and performed transcriptomic analysis to identify genes with different expression levels in each tissue. The results allowed me to create enzymatic profiles that distinguish these regions, with specific protease activities more prevalent in each different tissue (for example, aminopeptidase in the anterior portion, and cathepsin B and L far more active in the second and third regions). Interestingly, genes of the cytochrome P450 family showed more plasticity between tissues that we expected, possibly indicating different detoxification steps throughout the midgut. These tissue differences seem to be conserved from nymph to adult stages, which bodes well for a control strategy that may target staggered populations in the field. |
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