The effect of banker plants and pre-plant release on the establishment and pest control of Macrolophus pygmaeus in tomato greenhouses

Abstract

Biological pest control in greenhouses generally depends on the release of natural enemies. Macrolophus pygmaeus (Hemiptera: Miridae) is one of the most used predators in European vegetable crops. However, its long establishment time is considered as one of the main drawbacks in regard to pest control. Pre-plant release in nurseries and the use of banker plants are strategies frequently used to enhance the response of predatory mirids. The aim of this work was to determine how the length of the pre-plant release period in banker plants (PRP) and banker plant species influenced the establishment and population dynamics of M. pygmaeus and its pest control in tomato crops. Two PRPs (24 h and 30 days) and two banker plants (tomato, Solanum lycopersicum—Solanaceae, and Ballota hirsuta—Lamiaceae) were assayed in a complete factorial design with three replicates, in individual greenhouses. The proportion of individuals established, founder population, abundance and population growth rate of M. pygmaeus were significantly higher for the long than for the short PRP. For the long PRP, the founder population and abundance of M. pygmaeus in greenhouses were higher when B. hirsuta, rather than tomato, was used as banker plant. Lower incidences of Bemisia tabaci (Hemiptera: Aleyrodidae) and Tuta absoluta (Lepidoptera: Gelechiidae) were registered in greenhouses with the long PRP, while the effect of the banker plant was not significant. The higher proportions of individuals established and higher population growth rates of M. pygmaeus in the greenhouses with the largest founder populations suggest the implication of Allee effects.