Relationship between carrot weevil (Coleoptera: Curculionidae) infestation, damage, and planting dates of parsley (Apiaceae)

Abstract

AbstractSeasonal activity of carrot weevil,Listronotus oregonensis(LeConte), adults, eggs, larvae, and root feeding was studied in plots of parsley,Petroselinum crispum(Mill.) Nyman ex A.W. Hill, by sampling weekly from mid-May to the first week of September in 1998 and 1999. The initial population of overwintering adults, one complete generation, and at least a partial second generation were observed. The majority of eggs were deposited in June and most of the larvae were counted in July; the greatest damage was noticed from July onward. In both 1998 and 1999, the overall seasonal means of adults, eggs, larvae, and root feeding were significantly different among plots that were planted on different dates. Root feeding and all carrot weevil life stages sampled steadily decreased from the earliest to the latest planting. Most of the damage occurred in parsley plantings sown from late February until the third week of April. The number of eggs removed from parsley plants during the first cutting was significantly different among planting dates, but the impact of this removal may not be significant in infestation reduction. Results of this study will help parsley growers to target when control measures for carrot weevil will be most effective and which plantings are most likely to be damaged.