Locusts are a major crop pest in many parts of the world and different species are endemic to different countries. In Latin America, the South American Locust (Schistocerca cancellata) is the predominant species found mostly in Argentina, Chile, Bolivia, Paraguay, and southern Brazil with Argentina being the most affected. Several control and management practices, including biological control, have been implemented in these countries in the past to control the locusts and reduce their impact on crop and vegetation, however, effective long-term control and management practices will require a detail understanding of how the predominant locust species in this region responds to resource variation. Research has shown that there is strong evidence that locusts, and many other organisms, will actively balance dietary macronutrients (protein, carbohydrates, and lipids) to optimize growth, survival, and/or reproduction. A study by Cease et. al, 2017, on the dietary preferences of the Mongolian locust (Oedaleus asiaticus) showed that it prefers diets that are high in carbohydrates over diets that are high in protein, in this case locusts self-selected a 1:2 ratio of protein:carbohydrate. This and many other studies provide vital insight into the nutritional and feeding preferences of these locust species but the effects that this difference in protein: carbohydrate preferences has on growth, egg production, flight potential, and survival has yet to be fully explored, hence, this study investigates the effects that nitrogen fertilization of wheatgrass will have on the growth, egg production, survival, and flight muscle mass of the South American locust in a controlled, laboratory environment.

In Senegal, West Africa, soils are a vital resource for livelihoods and food security in smallholder farming communities. Low nitrogen (N) soils pose obvious challenges for crop production but may also, counterintuitively, promote the abundance of agricultural pests like the Senegalese locust, Oedaleus senegalensis. In this study I investigated how the abundance of locusts and grasshoppers are impacted by soil fertility through plant nutrients and how these variables change across land use types. We worked in two rural farming villages in the Kaffrine region of Senegal. Overall, there was little variation in soil properties and an agricultural landscape low in soil organic matter (SOM) and inorganic soil nitrogen. I corroborated that SOM is a significant driver of soil inorganic N, which had a positive relationship to plant N content. Of the management practices we surveyed, fallowing fields was important for soil nutrient restoration and years spent fallow was significantly correlated to inorganic soil N and SOM. O. senegalensis was least abundant in groundnut areas where plant N was highest. Additionally, I found a significant negative correlation between O. senegalensis abundance and plant N, suggesting that plant nutrients are an important driver of their populations. Grasshoppers, excluding O. senegalensis, were more numerous in grazing areas and fallow areas, perhaps due to a higher diversity of ecological niches and host plants. These results connect land use, soil, and vegetation to herbivores and suggest that improving soil fertility could be used as an alternative to pesticides to keep locusts at bay and improve crop yields.