Population dynamics of false wireworms (Gonocephalum macleayi, Pterohelaeus alternatus, P. darlingensis) and development of an integrated pest management program in central Queensland field crops: a review

Abstract

False wireworms (particularly Pterohelaeus alternatus and Gonocephalum macleayi) are major pests of seedling field crops in central Queensland. Population densities are spatially and temporally dynamic, with high densities (>2/m2) of large larvae and adults generally not persisting at a location for more than 1 year. Adult movement in summer in response to changes in habitat suitability is suggested as the cause of population changes. Natural enemies, particularly entomopathogenic fungi, may also have a role in suppressing high population densities. One-half to three-quarters of fields that have grown summer crops including sorghum, sunflower, soybeans, and mungbeans in the preceding season are infested at densities that could cause economic losses in subsequent crops sown in wide rows with a low seed-sowing rate. Winter-grown wheat results in a significantly lower infestation rate (one-quarter of the fields sampled), but winter chickpea is a suitable crop for development of false wireworm infestations. Cultivation per se does not reduce numbers of false wireworms, but stubble removal may depress densities. False wireworms feed on stubble, and crop damage may be increased in low-stubble fields (following long fallows for example) despite low false wireworm numbers, due to lack of alternative food. The dynamic nature of false wireworm population size makes prediction of pest levels difficult. The presence of false wireworms should be assessed in each fallow field before planting. Management strategies based on preplanting sampling, economic injury levels, stubble management, crop rotation, and insecticide control are discussed.