Biology and impact of the forest bug Pentatoma rufipes L. (Heteroptera,Pentatomidae) in pear and apricot orchards

Abstract: The forest bug, Pentatoma rufipes L. (Heteroptera, Pentatomidae), is a commonspecies found all over Europe. Nymphs and adults of this shield bug are polyphagous and feed onbuds, flowers and fruits of a wide range of shrubs and trees. Outbreaks in orchards can havemajor economic impacts, since pierced fruits can be heavily misshaped. Aiming to betterunderstanding the biology and impact of P. rufipes, several orchards were monitored in theValais (Switzerland). Weekly beating samples on pear and apricot trees revealed that P. rufipeshas a single generation per year and lives on fruit trees over the whole season. Insects hibernatein the second nymphal instar and adults emerge at the beginning of summer. Eggs are laid oversummer and hatching nymphs develop into the second instar until winter. Exposed egg baits wereattacked by predators, but there was no sign of parasitism. To study the date and appearance ofdamages, P. rufipes nymphs were released in sleeve cages enwrapping inflorescences of pear andapricot trees. Pears were badly misshaped when nymphs were released shortly after florescence;no visual damages were detected on apricots. In a laboratory insecticide trial, chlorpyrifosmethyl,lambda-cyhalothrin and pyrethrins killed almost all the nymphs exposed within a day.Diazinon, phosalone, spinosad and thiacloprid showed also a high efficacy, whereas azadirachtin-A and mineral oil were nearly without effect. Overall, these first observations might help todevelop a sustainable control strategy against this occasional pest.