Ácaros e insetos associados a diferentes variedades de lúpulo em quatro municípios do Estado do Rio de Janeiro

Abstract

In the state of Rio de Janeiro, the hops (Humulus lupulus L., Cannabaceae) has been gaining spaces in municipalities in the mountainous region. However, phytosanitary problems in this culture have already been detected, but few records of pests of this culture in Brazil have been found in the literature. However, key pest species of hops in other countries are known. This study had the following objectives: (1) to identify the species of phytophagous arthropodofauna associated with the leaves of H. lupulus and possible predatory insects, in seedlings or adult plants in Cachoeiras de Macacu, Cordeiro, Nova Friburgo and Seropédica, RJ and (2) evaluate the levels of infestation of the arthropod that most commonly infests the leaves of hop varieties in commercial plantations in Cordeiro and Nova Friburgo, in addition to identifying possible predatory insects. Phytosanitary inspections were carried out on hop plants from 03/July/2019 to 21/January/2020, when leaves were collected for identification of arthropods in the laboratory, where immature stages of insects found were reared to obtain adult for identification and biological data. The results obtained show that the hops served as a host plant for phytophagous arthropods of the classes Arachnida and Insecta, and that some of these phytophagous species are associated with predatory insects. The twospotted spider mite, Tetranychus urticae (Acari: Tetranychidae) infested the five evaluated hops varieties (Brazylinsk, Cascade, Hallertau, Saaz and Victoria) in both locations, but there was no difference in their infestation levels among the varieties, but the infestation was higher in Nova Friburgo than in Cordeiro. The insect predators of the twospotted spider mite were thrips of the genus Scolothrips (Thysanoptera: Thripidae) and ladybeetles of the genus Stethorus (Coleoptera: Coccinellidae). Frankliniella gemina (Thysanoptera: Thripidae) was another species of thrips identified, but has a phytophagous habit, being infrequent and occurring in a very small number. Hops are registered for the first time as a host plant for leafhopper, Aetalion reticulatum (Hemiptera: Aetalionidae) in Brazil, expanding the host series of this leafhopper. It was also observed the interaction of aggregations of A. reticulatum with Trigona spinipes (Hymenoptera: Apidae). Trialeurodes vaporariorum is recorded for the first time infesting hop leaves (Hallertau and Saaz varieties) in Brazil. This is the first hop record as a host plant for another 14 species of white flies from the subfamiliesAleurodicinae and Aleyrodinae distributed among nine inspected hop varieties (Brazylinsk, Cascade, Chinook, Columbus, Hallertau, Nugget, Saaz, Spalt and Victoria). Hops are also registered for the first time as a host plant for larvae of three species of Lepidoptera (Noctuidae, Noctuinae): Elaphria agrotina, Spodoptera dolichos and Spodoptera eridania, which were able to feed on hops leaves, the latter being predated by Ceraeochrysa cornuta larva (Neuroptera: Chrysopidae) in field conditions. It is concluded that T. urticae and T. vaporariorum were the only phytophagous species of common occurrence in other countries associated with hops, the first being more frequently found in commercial hop plantations in Nova Friburgo and Cordeiro.