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Cagliari, Italy

MacHtelinckx T.,Ghent University | Van Leeuwen T.,Ghent University | Van De Wiele T.,Ghent University | Boon N.,Ghent University | And 5 more authors.
BMC Microbiology | Year: 2012

Background: The predatory mirids of the genus Macrolophus are key natural enemies of various economically important agricultural pests. Both M. caliginosus and M. pygmaeus are commercially available for the augmentative biological control of arthropod pests in European greenhouses. The latter species is known to be infected with Wolbachia -inducing cytoplasmic incompatibility in its host- but the presence of other endosymbionts has not been demonstrated. In the present study, the microbial diversity was examined in various populations of M. caliginosus and M. pygmaeus by 16S rRNA sequencing and denaturing gradient gel electrophoresis. Results: Besides Wolbachia, a co-infection of 2 Rickettsia species was detected in all M. pygmaeus populations. Based on a concatenated alignment of the 16S rRNA gene, the gltA gene and the coxA gene, the first is phylogenetically related to Rickettsia bellii, whereas the other is closely related to Rickettsia limoniae. All M. caliginosus populations were infected with the same Wolbachia and limoniae-like Rickettsia strain as M. pygmaeus, but did not harbour the bellii-like Rickettsia strain. Interestingly, individuals with a single infection were not found. A PCR assay on the ovaries of M. pygmaeus and M. caliginosus indicated that all endosymbionts are vertically transmitted. The presence of Wolbachia and Rickettsia in oocytes was confirmed by a fluorescence in situ hybridisation. A bio-assay comparing an infected and an uninfected M. pygmaeus population suggested that the endosymbionts had minor effects on nymphal development of their insect host and did not influence its fecundity. Conclusion: Two species of the palaearctic mirid genus Macrolophus are infected with multiple endosymbionts, including Wolbachia and Rickettsia. Independent of the origin, all tested populations of both M. pygmaeus and M. caliginosus were infected with three and two endosymbionts, respectively. There was no indication that infection with endosymbiotic bacteria had a fitness cost in terms of development and fecundity of the predators. © 2012 Machtelinckx et al; licensee BioMed Central Ltd. Source

Marongiu G.,AGRIS Sardegna DIRVE | Sanna D.,AGRIS Sardegna DIRVE
Acta Horticulturae | Year: 2011

Tomato spotted wilt virus (TSWV) has recently been reported to cause severe damage to globe artichokes in Northern Sardinia (Italy). The disease is vectored by several thrips species previously regarded as secondary pests of this vegetable crop. For this reason, no specific control measures against thrips have been routinely adopted on globe artichokes. To evaluate their efficacy for the management of TSWV vectors, four insecticides currently registered in Italy for use on globe artichokes (spinosad, deltamethrin, lambda-cyhalothrin, and lufenuron), and two bio-insecticides used for thrips control on other crops (azadirachtin and a Beauveria bassiana-based product) were tested under semi-field conditions. While azadirachtin and B. bassiana were applied three times, all other products were sprayed twice. Twelve potted plants (4-10-leaf stage) were replicated four times in a completely randomized design. The mean number of live thrips present on four leaves randomly selected from each replicate was counted 3, 15, and 21 days after the first treatment. Infestation data were log-transformed prior to performing the ANOVA. The results achieved indicate deltamethrin and lambda-cyhalothrin to be the most active ingredients among the products tested. While spinosad and lufenuron proved effective after just two treatments, plants sprayed with B. bassiana and azadirachtin did not show any difference in terms of pest infestation compared to the controls. Although all the insecticides authorized for use on globe artichokes were found to be active against thrips, further studies are necessary to gather evidence of their efficacy for TSWV management. The two bio-insecticides tested here did not appear to be a reliable means of disease control. Source

Nannini M.,AGRIS Sardegna DIRVE | Atzori F.,AGRIS Sardegna DIRVE | Murgia G.,AGRIS Sardegna DIRVE | Pisci R.,AGRIS Sardegna DIRVE | Sanna F.,AGRIS Sardegna DIRVE
EPPO Bulletin | Year: 2012

The introduction of Tuta absoluta in Sardinia (Italy) has caused an important increase in the number of insecticide treatments applied for pest management on greenhouse tomatoes, thus raising growers' demand for alternative control options. To evaluate the efficacy of releasing two specimens of Macrolophus pygmaeus or Nesidiocoris tenuis per m 2 for the control of tomato borer infestations, an investigation was conducted under field conditions between August 2010 and July 2011. The tests were carried out on 18 commercial greenhouse crops. Fifteen other greenhouses, where no biocontrol agents were released, were also surveyed as controls. The release of the mirid bugs resulted in poor population growth of predators, which reached a peak density of 1.79 individuals per plant. In approximately half of the cases, this was caused by the application of pesticides (usually abamectin and oxamyl) which are highly toxic to the predatory mirids. However, even in crops where only products regarded as harmless to beneficials were used (e.g. Bacillus thuringiensis-based insecticides), both M. pygmaeus and N. tenuis failed to achieve the levels necessary for effective pest control. Presumably factors other than pesticide-related mortality contributed significantly to delaying mirid population build-up. Further studies are necessary to evaluate the feasibility of improving the efficacy of releases of the predatory mirids by the implementation of measures that may contribute to enhancing the establishment of these beneficials on tomato crops. © 2012 The Authors. Journal compilation © 2012 OEPP/EPPO. Source

Testa M.,AGRIS Sardegna DIRVE | Cadinu M.,AGRIS Sardegna DIRVE | Pilia R.,AGRIS Sardegna DIRVE | Pintore R.,AGRIS Sardegna DIRVE | Baghino L.,AGRIS Sardegna DIRVE
Acta Horticulturae | Year: 2013

Different extraction and detection methods were compared to evaluate the virus status of artichoke plants produced in vitro. These diagnostic procedures were performed to assess the efficacy of in vitro thermotherapy and/or meristem tips culture for obtaining virus-free plants. The viruses studied were: Artichoke Italian latent virus (AILV), Artichoke latent virus (ArLV), and Tomato spotted wilt virus (TSWV). In our experience, the most suitable detection method for in vivo analysis proved to be the tissue print hybridization on nylon membranes. This procedure is sufficiently sensitive and reliable, but at the same time less expensive than the other methods tested. When testing materials obtained in vitro, sometimes this method is not sufficiently sensitive, and false negatives frequently appear. The results of meristem tip culture showed that the excision of apices alone is generally insufficient to obtain AILV-free plants (3.3%), but better results were obtained for ArLV elimination (78.9% virus free plants ). The effectiveness of thermotherapy followed by meristem tip culture reached 100% for AILV and 0% for ArLV. For TSWV we have the result only of meristem tip culture, with percentage recovery of 98.51% (first Trial, subsequently abbreviated T1) and 45.95% (second Trial, subsequently abbreviated, T1R). Source

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