Life history traits ofCoccophagus gossypariae(Hymenoptera: Aphelinidae), a parasitoid of invasiveEriococcus spurius(Hemiptera: Eriococcidae) in field studies

Abstract

AbstractEriococcus spurius(Modeer) (Hemiptera: Eriociccidae) is a pest of American elm (Ulmus americanaLinnaeus; Ulmaceae) trees in western North America, but no effective biological control agent has been reported. This study took place in Calgary, Alberta, Canada, where urban American elms have been heavily and negatively impacted byE. spurius. Although the parasitoidCoccophagus gossypariaeGahan (Hymenoptera: Aphelinidae) was recovered from anE. spuriusinfested American elm in Calgary, little is known about its ecology. Prior to implementing biological control, the basic ecology of a candidate species must be understood. We documented the geographic establishment, sex ratios, and parasitism rate ofC. gossyparaieon its host within the study area. Coccophagus gossypariaehad established at 89% of study trees sampled and accounted for 98% of the parasitoids caught. They had a female-biased sex ratio of 13.7 females per male, and both males and females developed to maturity using the host. We found evidence of a highly consistent aversion to superparasitism by females in the field. This first investigation established a baseline of information on field populations ofC. gossypariaethat could lead to biological control ofE. spurius.