Date of Award

5-16-2024

Publication Type

Thesis

Degree Name

M.Sc.

Department

Biological Sciences

Keywords

Biological control;greenhouse;Miridae;pest control;strawberry;tomato

Supervisor

Sherah VanLaerhoven

Supervisor

Roselyne Labbé

Abstract

Greenhouse production represents a large component of Canadian agriculture, but native and invasive pests are a threat year-round. Diversifying pest management tools is essential to food security. Dicyphus hesperus (Hemiptera: Miridae) is a well-established native biological control agent applied in commercial greenhouses. Lab colonies were established for two previously unassessed native species—D. discrepans and D. famelicus. We assessed longevity and fecundity of D. famelicus on tomato, mullein, and strawberry in the presence and absence of prey, and found that D. famelicus is an obligate omnivore on mullein and tomato plants. All mirids lived longer when provided with prey regardless of host plant. Mirids required prey to produce a second generation of nymphs (p < 0.0001). We provided mirids with prey in an enclosed arena to assess their consumption of greenhouse whitefly, green peach aphid, and two-spotted spider mites. There was no difference between predator sex (p = 0.19) or species (p = 0.34) in consumption of green peach aphids. Dicyphus hesperus consumed more two-spotted spider mites (p = 0.016) than D. famelicus and D. discrepans. Female mirids consumed more whitefly than males, and D. hesperus consumed more than D. discrepans, with D. famelicus intermediary to both. Finally, greenhouse trials measured the potential of these predators to control pests on tomato and strawberry and assessed damage. Mirid species impacted whitefly population and mirid population (p < 0.0001) with higher whitefly and lower mirids in the control, D. discrepans and D. famelicus treatments than in the D. hesperus treatment. In strawberry crops, the diameter (p = 0.035) and mass (p >0.0001) of the fruit set was larger with mirids present. Implementing Dicyphus species could enhance native beneficial predator populations for sustainably managing pests in greenhouse production systems.

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Entomology Commons

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