Wireworm Populations in Relation to Crop Production

Abstract

It is well known that infestation is only one of a number of factors which determine the amount of wireworm damage occurring in a field. As an attempt to analyse the conditions under which crops fail from wireworms, thirteen fields showing both damaged and undamaged areas were studied. Data were collected on wireworm populations, chemical and mechanical composition of the soil, feeding reactions of the wireworms collected, agricultural history and treatment of the different plots and fields. In six only of the fields did the damaged areas coincide with areas of higher infestation. In the remainder, the failures occurred at low populations, and no marked differences in population could be detected between the failing and successful plots. The levels of population at which the failures occurred varied between wide limits in the different fields. Two of the edaphic factors investigated were associated consistently with the failing and successful plots; CaCO3 was consistently higher and sand content consistently lower on the failing plots. Differences in these factors were particularly noticeable in those fields where differences in infestation were not detected. There is a suggestion from four of the fields that wireworm attack commonly follows sainfoin. None of the other factors showed significant relationships. Although the results suggest that differences in one or more of the factors, infestation, CaCO3 and sand, are associated with differences in wireworm damage within fields, the differences between the fields cannot be explained so simply. Evidently, other factors, relatively uniform within single fields but varying from field to field, also influence the amount of wireworm damage. Consideration of the results in relation to wireworm and plant populations brings out the need for greater attention to the role of wireworm activity and the environmental factors which influence it. The importance of reliable methods for predicting wireworm damage to any methods of control is stressed.