School of BioSciences - Theses

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Start date: 2020 × End date: 2021 × Subject: Insecticide × Subject: Aphid ×

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    Understanding and incorporating aphid parasitoids within IPM strategies in Australian grain crops
    Ward, Samantha Elizabeth ( 2020)
    Aphids (Hemiptera: Aphididae) can be particularly devastating to grain crops, with their economic importance weighted on their ability to cause significant yield losses through a variety of methods. From feeding damage alone in 2012, cereal aphids caused an average annual loss of $14 million in Australian wheat crops. For over a century, growers have relied upon host plant resistance and chemical treatments to control invertebrate pests, however suppression of beneficial organisms and increased resistance within targeted species has created an ongoing battle with pest control. For example, the polyphagous green peach aphid (Myzus persicae (Sulzer)), often a pest of canola crops, has developed resistance to over 74 insecticides including carbamates, pyrethroids, and organophosphates around the world. Due to these issues, control of agricultural pests is now focussed on Integrated Pest Management (IPM) strategies, within which natural enemies can play a role as biological controls. Parasitoid wasps have had the most success as biological control organisms in the past, likely due to their host specificity. I spent three years collecting data on grain aphid pests and their associated natural enemies, paying particular attention to the hymenopteran parasitoids. I determined the distribution of grain aphids and their associated Aphidiinae within grain production landscapes around Australia, utilising historic data and citizen science. Additionally, I determined how aphid abundance and diversity, along with their associated parasitoids changed throughout the growing seasons. I created a key of aphid parasitoids (Hymenoptera: Aphidiinae) parasitizing aphids in Australian grain production landscapes. Finally, I determined the effects of seed treatments on specific natural enemies associated with M. persicae, identifying the difference between parasitoid and predator effects. My findings are informative for developing strategies to conserve those Aphidiinae species of particular importance in controlling aphid pests. Additionally, these results can assist with pest management decisions, enabling growers to implement IPM based on a greater breadth of knowledge.