The role of ecological gradients and host-parasitoid interaction in tropical insect communities

Sam Cameron FINNIE

Doctoral thesis

Abstract:

The thesis explores the various biotic and abiotic factors that drive change in insect communities with particular emphasis on host-parasitoid interactions. These factors range from ecological gradients to defensive traits and host specialisation. The aim of the first chapter was to determine how the assemblage of an ecologically and anthropocentrically significant group of insects changed in response to altitude. This study highlighted the elevational limit of fruit flies and discovered that a new and promising attractant lure used in agriculture was particularly useful at higher altitudes, potentially opening new avenues for pest management in mountainous regions. The aim of the second chapter was to ascertain the physiological and phylogenetic traits of galling insects that alter the diversity and host specificity of their parasitioids. This research not only uncovered a remarkably specialist community of gall parasitoids, and found significant physiological drivers of parasitoid assemblage, it also broached the possibility of a latitudinal gradient in gall parasitoid host specificity, that warrants further exploration due to its potential implications for biodiversity patterns. The final chapter, aimed to uncover patterns in the vertical stratification of a caterpillar-parasitoid community, and whether any potential patterns and interactions are driven by the defensive traits of the caterpillar hosts. This study provided further evidence that the defensive traits of caterpillars influence their vulnerability to parasitism, and discovered distinct patterns in the vertical stratification of caterpillar communities. Overall, this holistic research expands upon the existing literature on tropical insect ecology and advances our understanding on the complex interactions between insects and their environment.

Abstract:

The thesis explores the various biotic and abiotic factors that drive change in insect communities with particular emphasis on host-parasitoid interactions. These factors range from ecological gradients to defensive traits and host specialisation. The aim of the first chapter was to determine how the assemblage of an ecologically and anthropocentrically significant group of insects changed in response to altitude. This study highlighted the elevational limit of fruit flies and discovered that a new and promising attractant lure used in agriculture was particularly useful at higher altitudes, potentially opening new avenues for pest management in mountainous regions. The aim of the second chapter was to ascertain the physiological and phylogenetic traits of galling insects that alter the diversity and host specificity of their parasitioids. This research not only uncovered a remarkably specialist community of gall parasitoids, and found significant physiological drivers of parasitoid assemblage, it also broached the possibility of a latitudinal gradient in gall parasitoid host specificity, that warrants further exploration due to its potential implications for biodiversity patterns. The final chapter, aimed to uncover patterns in the vertical stratification of a caterpillar-parasitoid community, and whether any potential patterns and interactions are driven by the defensive traits of the caterpillar hosts. This study provided further evidence that the defensive traits of caterpillars influence their vulnerability to parasitism, and discovered distinct patterns in the vertical stratification of caterpillar communities. Overall, this holistic research expands upon the existing literature on tropical insect ecology and advances our understanding on the complex interactions between insects and their environment.

Keywords

Vertical stratification, elevational gradient, defensive traits, caterpillars, galls, tephritidea, parasitism rates, parasitoid richness

Language used: English

Date on which the thesis was submitted / produced: 22. 5. 2024

Thesis defence

• Supervisor: Mgr. Kateřina Sam, Ph.D.

UNIVERSITY OF SOUTH BOHEMIA IN ČESKÉ BUDĚJOVICE

Faculty of Science

Doctoral programme / field:
Biology / Entomology