ABSTRACT
Bark and ambrosia beetles, mainly the ones belonging to groups Scolytinae, Bostrichidae and Platypodinae, can kill trees from reforestation areas or native forests and damage the wood. Population monitoring and the identification of quarantine species are carried out by assembling ethanol-baited traps. The aims of the current study are to evaluate the influence of the color of ethanol-baited traps on the efficient capture of these insects, as well as to measure changes in colorimetric variables based on trap exposure in the field and to investigate whether these changes affect capture efficiency. Eight ethanolic traps (red, yellow, black and transparent traps - two of each color) were installed in a forest fragment in the first experimental stage samples were collected on a weekly basis, for 11 months. New and used transparent traps were installed in the field in the second experimental stage - samples were collected for additional 11 months. A portable spectrophotometer was used to measure the colorimetric variables in these traps. The mean number of Scolytinae individuals (± SD) captured in transparent traps (48±50) was significantly higher than that of individuals captured in black (24±25), yellow (23±21) and red (22±21) traps. However, transparent traps subjected to field conditions were colonized by such as fungi, bacteria and mosses, which changed the transparent state of the traps into a darkened color and significantly affected their capture efficiency. The total number of 6,268 Scolytinae individuals were collected at this experimental stage: 4,977 of them were captured in new traps, whereas 1,291 were captured in the old ones. Based on the herein measured colorimetric variables, such color change got significantly intensified as transparent traps remained under field conditions. In conclusion, transparent traps were more efficient in capturing Scolytinae individuals than the black, yellow and red traps. In addition, the exposure to field conditions has progressively changed equipment color and decreased its capture efficiency.
Subject(s)
Coleoptera , Pest Control/methods , Weevils , EntomologyABSTRACT
ABSTRACT: Stem bleeding disease, caused by the fungus Thielaviopsis paradoxa is one of the most important diseases of coconut palm Cocos nucifera worldwide and some insect species have been found in association with T. paradoxa infected coconut palms. The present research investigated whether coconut palm-infesting bark beetles (Coleoptera: Curculionidae: Scolytinae) could disseminate stem bleeding disease. Adult bark beetles collected from coconut palms presenting stem bleeding symptoms were inoculated in PDA culture medium. Results showed no germination of the fungus T. paradoxa from either cuticle or digestive tract of bark beetles. Thus, we found no evidence that bark beetles carry viable spores of T. paradoxa that could infect healthy coconut palms and disseminate stem bleeding disease.
RESUMO: A resinose, causada pelo fungo Thielaviopsis paradoxa, é uma das doenças mais importantes do coqueiro Cocos nucifera em todo o mundo, e algumas espécies de insetos têm sido encontradas em associação com coqueiros infectados por T. paradoxa. O presente trabalho investigou se os besouros escolitíneos (Coleoptera: Curculionidae: Scolytinae) poderiam disseminar a resinose a partir de coqueiros infectados. Escolitíneos adultos coletados de coqueiros com sintomas da resinose foram inoculados em meio de cultura BDA. Os resultados mostraram que não houve germinação do fungo T. paradoxa da cutícula ou do trato digestivo dos insetos. Assim, não encontramos evidências de que besouros escolitíneos carreguem esporos viáveis de T. paradoxa que pudessem infectar coqueiros e disseminar a doença resinose.