The bean weevil, Acanthoscelides obtectus Say (Coleoptera: Chrysomelidae: Bruchinae), causes severe post-harvest losses in the common bean, Phaseolus vulgaris L. The control of this insect is still poor and involves the use of conventional insecticides. There is an increasing demand in the search for new active substances and products for pest control towards reduction of adverse effects on human health and the environment. The protection of grains with alternative products, such as essential oils, is a possible alternative to meet the needs described above. Therefore, this investigation evaluated the applications of basil, Ocimum basilicum, and citronella, Cymbopogon winterianus, essential oils for A. obtectus control. These essential oils significantly reduced the bean weight losses and the number of beans damaged by A. obtectus at higher doses than 60 or 120 μL/sample. The number of holes per bean did not differ between the doses of basil essential oil, not even at the dose of 60 μL, while it was higher at 120 μL, probably due to a lower capacity of movement of the insects treated with this dose and/or the oil’s direct or indirect effects on the insects. Basil and citronella oils exhibited similar patterns of insecticidal activity over the insect, both directly in adult insects or indirectly over bean seeds. These essential oils affected the development of A. obtectus since the greatest doses applied on beans decreased the emergence of the bean weevil. The results prove the insecticidal capacity of the tested essential oils and hence their potential as active substances against A. obtectus in environmentally low risk pest control strategies. Supplementary trials should be conducted under real storage conditions.

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Trichoderma is a genus of fungi used for the biological control of plant diseases and a large number of its bio-formulates are available in the market. However, its efficacy under field conditions remains unclear, especially for the protection of grapevine plants against Grapevine Trunk Diseases (GTDs). These diseases are caused by a complex of fungal pathogens whose main point of entrance into the affected plants is through pruning wounds. In this research, different Trichoderma native strains have been evaluated according to their ability to grow at different temperatures and their capacity to colonize pruning wounds in adverse climatic conditions. Strains from section Trichoderma have adapted to cooler conditions. On the other hand, strains from clade Harzianum/Virens grow at higher temperatures. However, differences can also be found between strains inside the same clade/section. Native strains were able to colonize more than 70% of vine pruning wounds in winter conditions. The Trichoderma strain T154 showed a significantly higher re-isolation degree from vine plants and its concentration was optimized for spraying onto vine plants. In conclusion, Trichoderma native strains are better adapted to survive in a changing environment, and they could give better protection to grapevine plants in co-evolution with each specific vineyard.

The interest in the study of microbiological interactions mediated by volatile organic compounds (VOCs) has steadily increased in the last few years. Nevertheless, most assays still rely on the use of non-specific materials. We present a new tool, the volatile organic compound chamber (VOC chamber), specifically designed to perform these experiments. The novel devices were tested using four Trichoderma strains against Fusarium oxysporum and Rhizoctonia solani. We demonstrate that VOC chambers provide higher sensitivity and selectivity between treatments and higher homogeneity of results than the traditional method. VOC chambers are also able to test both vented and non-vented conditions. We prove that ventilation plays a very important role regarding volatile interactions, up to the point that some growth-inhibitory effects observed in closed environments switch to promoting ones when tested in vented conditions. This promoting activity seems to be related to the accumulation of squalene by T. harzianum. The VOC chambers proved to be an easy, homogeneous, flexible, and repeatable method, able to better select microorganisms with high biocontrol activity and to guide the future identification of new bioactive VOCs and their role in microbial interactions.

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