Spring Emergence and Seasonal Flight ofDelia radicumL. (Diptera: Anthomyiidae) in Western Oregon

Seasonal Flight, Optimal Timing and Efficacy of Selected Insecticides for Cabbage Maggot (Delia radicum L., Diptera: Anthomyiidae) Control

“…It is known that cabbage maggot development may be stimulated by rainfall [ 28 ]. After emergence, flies feed on pollen and nectar produced by various plants [ 9 ], and start to mate and lay eggs approximately one week after emergence. Cabbage maggot adults deprived of host plants are less selective in choosing oviposition sites compared to females able to continuously lay eggs on host plants [ 29 ].…”

“…The foliar application of insecticides corresponded with a maximum number of eggs ( Figure 3 ). If we assume that larval emergence starts three to nine days after oviposition [ 9 ], it seems likely that foliar sprays were applied at the correct time and that timing was not the reason for poor efficacy.…”

“…The device was calibrated to measure the air temperature three times per day and to recalculate the average daily temperature by dividing the sum of minimum and maximum by 2. From the collected climatic data starting 1 January, we calculated mean degree-day accumulation (DDA) by using the lower thermal threshold of 4.3 °C and upper thermal threshold of 30 °C as it was proposed by Derves et al [ 9 ]. Cumulative precipitation also was calculated starting with 1 January.…”

“…The cabbage maggot overwinters as a pupa in the soil. The timing of spring emergence of adults and ovipostion activity depends on spring emergence patterns of cabbage maggot populations as a function of degree-day accumulation and can vary widely [ 9 ]. Forecasting systems should be based on an understanding of flight behavior of cabbage maggot adults and the relationships between adult flight activity, oviposition, crop damage and environmental conditions.…”

“…Forecasting systems should be based on an understanding of flight behavior of cabbage maggot adults and the relationships between adult flight activity, oviposition, crop damage and environmental conditions. Degree-day models have been widely used to assist in the development of control strategies for the cabbage maggot in many EU countries [ 10 , 11 ], the USA [ 9 , 12 , 13 ] and in Canada [ 14 ]. Most authors agreed that understanding temporal patterns of abundance is an important prerequisite for formulating appropriate management strategies and that regional risk forecasts need to take into account the emergence patterns of local populations.…”