South-East European Forestry (Dec 2014)
New Records of Bruchidius Spermaphagous Species in Albizia julibrissin and Laburnum anagyroides and Their Parasitoid Complex in Serbia
Abstract
Background and Purpose: Bruchidius villosus feeding in seed of Laburnum anagyroides, and Bruchidius terrenus seed pest of Albizia julibrissin are first recorded and completely new seed-beetle to Serbian Bruchinae fauna. This Chrysomelids which were found in Republic of Serbia during intensive studies from 2012 to 2014 are likely related to a mostly Paleotropical group, including also members of genera Bruchidius, Megabruchidius and Acanthoscellides. These seed-beetles develop in pods of these two woody legumes, widely grown ornamental trees and shrubs. Several recent reports reveal that this species are well established in France, Hungary, and Bulgaria. Materials and Methods: Bruchine and their legume hosts were observed by extensive field sampling throughout Serbia over three years and by rearing the beetles from the samples in the laboratory. Bruchines and the parasitoids were mass-reared in climate controled rooms under conditions close to those of their area of origin: 12:12 L:D, 3-23 °C and ≤80 % RH (depends of host plant ongoing phenology or experimental needs-proof of weevil monophagous feeding preferences). For the purpose of analyzing the observed phenomena (its intensity and relevance), some of the standard methods of statistical analysis and conclusion have been used. Results: Levels of seeds infestation still in the pods were high and comparable to other studies. Bruchine beetle infestation in the dehiscent fruits of host plants may be greater after the seeds and pods drop to the ground, as bivoltine generation occurs, but this has yet to be tested. Hypotheses on the geographic origin of this new species are also discussed. The effect of native parasitoids occurrence could potentially be interesting, given that their appearance suggest their specialization on the Bruchidius beetle species which is a common seed-predator on the leguminous seeds. Conclusions: The establishment of this new species is investigated using both morphological data and idioecological analyses. For this purpose, a methodology was developed to assess weevil field densities in a natural environment. However, this needs to be more carefully tested with a larger sample size and experiments. Significant levels of infested seed, leads to the conclusion that these seed parasites could be an important reducing factor of generative reproducing host plant potential.
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