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United States Department of Agriculture

Agricultural Research Service

Title: Impact of Planting Date on Sunflower Beetle Infestation and Damage at Four Locations in North Dakota

Authors
item Charlet, Laurence
item Knodel, Jan - NDSU
item Harbour, Jim - NDSU

Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings
Publication Acceptance Date: January 29, 1999
Publication Date: N/A

Interpretive Summary: The sunflower beetle is a pest of cultivated sunflower. Both the adults and larvae feed on sunflower foliage. The purpose of these studies was to increase knowledge of beetle biology and determine the impact of cultivation and planting date as pest management tactics. Females produced 854 eggs over a period of 60 days with a mean of 14 eggs/day. Males lived 99 days and females 86 days. Over 75% of the eggs were fertile. In the field, egg survival was higher earlier in the season. Larval populations on sunflower plants in 5 commercial fields showed densities significantly higher 100m into the field than on the edge, 20m, or 50m into the field. Therefore sampling needs to include areas at least 100m into the field in order to accurately determine larval population density. There were no differences in larval parasitism rates among any of the 4 locations within the field. Overwintering sunflower beetle adults were more abundant within the field than at the margin, indicating that the adults do not move away from the field to overwinter. Neither fall nor spring cultivation reduced survival of overwintering adults. Thus, disturbing the adults by disking the field either in the fall or spring does not have a negative impact on their survival. It also appears that cultivation does not influence the pattern of adult emergence from the soil. Adult and larval populations decreased as planting date was delayed. Defoliation was lowest in the latest date of planting. There was no difference in the rate of parasitization among all three planting dates. It appears that delaying sunflower planting is an effective management strategy to reduce beetle populations and subsequent feeding damage and also does not negatively impact biological control of the beetle.

Technical Abstract: The sunflower beetle is a pest of cultivated sunflower. Both the adults and larvae feed on sunflower foliage. The purpose of these studies was to increase knowledge of beetle biology and determine the impact of cultivation and planting date as pest management tactics. Females produced 854 eggs over a period of 60 days with a mean of 14 eggs/day. Males lived 99 days and females 86 days. Over 75% of the eggs were fertile. In the field, egg survival was higher earlier in the season. Larval populations on sunflower plants in 5 commercial fields showed densities significantly higher 100m into the field than on the edge, 20m, or 50m into the field. Therefore sampling needs to include areas at least 100m into the field in order to accurately determine larval population density. There were no differences in larval parasitism rates among any of the 4 locations within the field. Overwintering sunflower beetle adults were more abundant within the field than at the margin, indicating that the adults do not move away from the field to overwinter. Neither fall nor spring cultivation reduced survival of overwintering adults. Thus, disturbing the adults by disking the field either in the fall or spring does not have a negative impact on their survival. It also appears that cultivation does not influence the pattern of adult emergence from the soil. Adult and larval populations decreased as planting date was delayed. Defoliation was lowest in the latest date of planting. There was no difference in the rate of parasitization among all three planting dates. It appears that delaying sunflower planting is an effective management strategy to reduce beetle populations and subsequent feeding damage and also does not negatively impact biological control of the beetle.

Last Modified: 12/21/2014
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