Sampling arthropod pests and natural enemies in stored barley

Abstract

Application of pest management programs for the food industry reduces pesticide applications, increases the effectiveness of pest suppression to acceptable levels and reduces the cost and risk of negative non-target effects. In these programs, efficient sampling is a decisive factor for undertaking management measures. In this study, a one year survey of arthropods attacking stored barley and their natural enemies was conducted in two experimental piles, in which no fumigation was applied. Sampling was performed on a monthly basis with a grain sampling trier, with pitfall traps and yellow sticky traps. The parasitoid Anisopteromalus calandrae was released twice in one of the piles with the aim of testing its establishment and control capacity on the infesting beetles.Seven coleopteran and one psocid species formed the assemblage of pests that attacked the two barley piles, among which Sitophilus granarius, Rhyzopertha dominica and Latheticus oryzae were the most abundant species. Two parasitoids, A. calandrae and Cephalonomia waterstoni, and one predator, Withius piger, were the beneficial organisms found. Two releases of A. calandrae were successful in establishing the parasitoid, but they were not enough for controlling either S. granarius or R. dominica. Pitfall traps captured the same complex of species as the grain sample trier but the abundance of each species was not always the same in both devices. These traps were good for detecting the early presence of most species. Yellow sticky traps only captured some species from the pest complex and trapped high numbers of the parasitoid A. calandrae. They can be of help as indicators of the colonization of some specific pests, such as R. dominica, in the first weeks of the invasion process.