Management of Delia (Diptera: Anthomyiidae) through selectively timed planting of Phaseolus vulgaris (Fabaceae) in Atlantic Canada

Abstract

AbstractDelia Robineau-Desvoidy (Diptera: Anthomyiidae), including Delia platura (Meigen), are known pests of vegetable crops. Here, three studies were conducted to examine the relationship between Delia species and Phaseolus vulgaris Linnaeus (Fabaceae). Field studies documented a relationship between planting date and occurrence of Delia damage on P. vulgaris. Plantings in mid-June resulted in higher crop yields (mean bean pods per plant) and reduced damage ratings compared with earlier plantings. Late-May and early-June planting dates were not favourable, as they resulted in high damage ratings and low plant survival. Late-June and July plantings resulted in low damage ratings but low crops yields. Growth chamber experiments examined oviposition preference of D. platura females at eight phenological stages for two varieties of P. vulgaris. Results indicated significantly higher oviposition rates on bean plants at early phenological growth stages, with no significant varietal preference shown by maggots. Laboratory experiments quantified the impact of D. platura larval infestation on two P. vulgaris varieties at two growth stages. Results indicated no significant difference in variety choice. Recommendation for planting P. vulgaris to coincide with Delia phenology using a degree-day model is discussed.