Date of Award


Publication Type


Degree Name



Biological Sciences


Biocontrol, Diversity, Fecundity, Functional response, Life history, Nabis americoferus


S. VanLaerhoven


R. Labbe




Invasive species have become a grave threat to the economic viability of our global vegetable producers. Tomato pinworm Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) has expanded from its range originating from Peru to being established in nearly hundreds of countries, causing tomato production losses of up to 100% on occasion; however, it has not yet been found in Canada or the USA. Southwestern Ontario is a significant tomato producer making it a high risk from this invasive species. Efficient integrated control methods such as native biological control agents (BCAs) that avoid creating insecticide resistance are ideal. Surveys of Southwestern Ontario conservation areas for predatory hemipteran families such as Miridae and Nabidae were done to understand the local diversity and identify new potential native BCAs. Surveys indicated conservation areas were highly fragmented with a lack of diversity between interior and exterior sites of conservation sites. However, larger areas showed the highest diversity overall, providing the most opportunity for discovering new BCAs. Nabis americoferus Carayon (Hemiptera: Nabidae) was identified as a potential new BCA through these surveys, and multiple life history and predatory traits were examined to evaluate its potential as a BCA on tomato crops. Nabis americoferus has a quick mean growth rate of 18 days from egg to adult, lengthy longevity with females living upwards of 112 days, a mean lifespan of 58 days, and high overall reproductive output with a mean of 43 nymphs per female lifetime fecundity upon tomato (Solanum lycopersicum) plants. These metrics are similar to currently used BCAs against T. absoluta in affected regions in other regions around the globe. Nabis americoferus has shown great voracity in the consumption and response to typical tomato pests such as Myzus persicae Sulzer (Hemiptera: Aphididae) and other lepidopteran pests similar to T. absoluta such as Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) and Trichoplusia ni Hubner (Lepidoptera: Noctuidae). On these prey, female N. americoferus adults consume a mean of 56 first instar larvae and 38 eggs, respectively, in 24h. Taken together, these experiments demonstrate that N. americoferus can reproduce and voraciously predate pest populations common on tomato systems. Although more studies are needed, N. americoferus has demonstrated potential as a protective and pre-emptive tool against the establishment of T. absoluta and other tomato pests.