The efficiency of several sampling methods for Frankliniella occidentalis (Thysan., Thripidae) in strawberry flowers

Abstract

Abstract:Methods for sampling western flower thrips Frankliniella occidentalis (Pergande) (Thysan., Thripidae) in strawberry flowers were evaluated in three commercial plots by monitoring the population densities of adult and immature thrips throughout the growing season. Three types of flowers were sampled: open, senescent and petal fall, and three procedures were compared: a visual examination of flowers, a turpentine‐funnel method and a shake method. Open flowers showed higher population densities of adults, whereas senescent or petal fall flowers had a higher number of eggs and more damage symptoms. Seasonal changes in population density were similar for the three sampling procedures, although the turpentine method recovered more insects, especially larvae, than the other two methods. The turpentine procedure was the most efficient as it extracted almost 100% of adults and, in plots with no chemical sprays, nearly 100% of second instars and 50% of first instars. Regular control of thrips with pesticides reduced the percentage of larvae recovered with this procedure. The visual method spotted 80% of adults and 33% of larvae. The shake method extracted nearly 80% of adults but only 18% of larvae. The visual method is recommended for routine field samplings, especially for sampling adults and in plots regularly sprayed with pesticides, as it constitutes a cost‐effective method when time and efficiency are considered.