Effects of crowding on disease resistance in a butterfly host Open Access
Alaidrous, Wajd (Spring 2021)
Published
Abstract
Host density is an important factor when it comes to parasite transmission and host resistance. Studies have shown that increased host density can increase contact rate between individuals and, thus, parasite transmission. However, host density can also cause physiological changes in the host, which can affect host resistance. Yet, the direction in which host density affects host resistance remains unresolved. It is also unclear whether food limitation plays a role in this effect. We investigated the effect of larval density of monarch butterflies, Danaus plexippus, on the resistance to their natural protozoan parasite Ophryocystis elektroscirrha under both unlimited and limited food conditions. We exposed monarchs to various density treatments as larvae to mimic high densities observed in sedentary populations. Data on infection probability and parasite spore load were collected as well as development time, survival, and wing morphology. Results showed that higher larval densities had minimal effects on development time and adult lifespan. Food limitation caused slightly stronger effects of density on development time, survival, and wing size and color. However, these effects were small in size, and most likely not attributed to increased infection as crowding did not show increased disease susceptibility under either food conditions. This study helps in understanding the dynamics of environmental parasite transmission in monarch populations, which can help explain the increased prevalence of parasites in sedentary monarch populations compared to migratory populations.
Table of Contents
Introduction .....................................................................................................................................1
Method ............................................................................................................................................5
Caterpillar source and rearing...............................................................................................5
Survival ..............................................................................................................................8
Development time................................................................................................................8
Adult lifespan, parasite load, and tolerance ............................................................................8
Wing size and hue.................................................................................................................9
Statistical analysis............................................................................................................... 10
Results........................................................................................................................................... 11
Unlimited Food Experiment ................................................................................................ 11
Food Limitation Experiment ............................................................................................... 18
Discussion...................................................................................................................................... 24
References ..................................................................................................................................... 28
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Effects of crowding on disease resistance in a butterfly host () | 2021-04-13 18:10:07 -0400 |
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