Meeting Abstract
Temperature and nutrition influence the growth and development of all organisms, with the interaction between insects and their diseases being very complex. For locusts, body temperature influences their rate of development along with the nutritional resources extracted from their host plants (through differential digestion) and the growth rates of any microbes or pathogens they harbor. We quantified the growth and development the Australian plague locust and the fungus Metarhizium anisopliae var. acridum, across a range of temperatures and diets. Heat maps demonstrated the thermal and nutritional optima’s for both the locust and the fungus differ significantly, with a little overlap. At constant temperatures the locust can only complete its life cycle between 26-44 oC with growth being fastest and heaviest at 41 oC on a slightly carbohydrate biased diet, while the fungus grows fastest at 26 oC on a protein–biased diet, with no detectable growth below 15 or above 35 oC. However, the fungus is able to ‘kill’ its host as it can withstand both high and low temperatures for at least a month and when returned to its temperature optima, is able to grow. Thus, the fungus survives due to daily temperature fluctuations, which it exploits, eventually overwhelming the locust.
