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Soybeans in Brazil stand out as the major grain grown throughout the country, being economically and socially essential. However, there are several limiting factors for its production such as diseases caused by nematodes, mainly the species of the genus Meloidogyne sp. that prevent the production in infested areas. In order to find new alternatives for the protection and control of such disease, the following study aimed to determine the nematicidal activity of Melaleuca alternifolia oil in its pure form and solid lipid nanocarriers containing the oil. It was found that both the pure essential oil and its nanostructured form presented nematicidal potential in vitro and in vivo , however, at different times of action. All concentrations were active and similar regarding action to abamectin, the conventional treatment. In this sense, this paper for the first time presents the action of M . alternifolia nanoparticles in the treatment/prevention of infections by Melodogyne sp.

The aim of this study was to evaluate the in vitro susceptibility of larva and adult forms of Alphitobius diaperinus treated with cinnamon (Cinnamomum zeylanicum) essential oil on its free form, nanoemulsion (NE), and nanocapsule (NC), as well as the effect of these treatments on the edaphic fauna using springtails of Folsomia candida (ISO) as a model. The tests with larvae and adults were performed using 1, 5, and 10% of the cinnamon essential oil, and 0.5, 1, and 5% of NE and NC containing 5% of cinnamon essential oil. To validate the test, three controls were used: only oil diluent (Triton), blank nanoemulsion (without oil) and blank nanocapsule (without oil). Cinnamon essential oil at 5 and 10% caused mortality in larva and adult forms of A. diaperinus. The NE (1%) and NC (5%) caused mortality in both phases of A. diaperinus life cycle. After these promising findings, more studies were conducted to verify the ecotoxicological effect of the cinnamon oil. For this, a Tropical Artificial Soil (TAS) was used with different doses of cinnamon oil, NE and NC, using springtails of F. candida. The use of cinnamon oil, even in very low concentrations (25 mg kg− 1), on its original form significantly affected springtails survival and reproduction. However, the nanostructuring process seemed to minimize this toxic effect without affecting its insecticidal action. In summary, the pure oil and NE containing cinnamon oil showed effect against A. diaperinus, and may be considered an alternative to control this infestation.

Antimicrobial activity of Amazonian oils Andiroba and Copaiba against Paenibacillus larvae has been recently determined, indicating their potential use for the control of American Foulbrood Disease (AFB), but the use of essential oils in the environment still represents a challenge. The oils present several volatile elements in its composition, such high volatility being the cause of a sharp decline in antimicrobial activity. In this context the nanostructuration of these amazon oils may decrease the volatile characteristic of such products. The following research aimed to evaluate the activity of nanoemulsions prepared with Andiroba and Copaiba oils against Paenibacillus species. The toxicity of nanoemulsions has also been investigated with larvae and adult worker bees. Nanoemulsions (NE1, 10% Andiroba oil; NE2, 10% Copaiba oil; and NE3, 10% medium-chain triglyceride as negative control) were prepared in a high pressure homogenizer. The particle sizes were determined as 192, 211, and 178 nm for NE1, NE2, and NE3, respectively. The z potential values were − 56.4, − 47.1, and − 27.2, respectively. NE1 and NE2 showed minimal inhibitory concentration (MIC) values lower than 0.39% for most Paenibacillus species tested. None of the strains were inhibited by negative control NE3. The time-response effect of the nanoemulsions has been tested on P. larvae ATCC9545, resulting in a decrease in the number of viable cells to less than 1 log CFU/ml for NE1. The nanoemulsion NE1 showed a significant toxic effect for the larvae (26% mortality) when compared with NE2 (13%) and NE3 (7%). The toxic effect of nanoemulsions has also been evaluated for 72 h in adult worker bees and low mortality rate was only observed for the NE1 treatment (8.3%). This study shows for the first time that nanoemulsions of Copaiba oil can be a potential candidate for the treatment or prevention of AFB.

Paenibacillus larvae and Melissococcus plutonius are the primary bacterial pathogens of honeybees and the causative agents of American and European foulbrood disease (AFB and EFB) respectively. Such diseases have been gaining importance since there are few therapeutic options beyond the reporting of microorganisms resistant to conventional antibiotics. Due to the inefficiency and/or low efficacy of some antibiotics, researches with nanotechnology represent, possibly, new therapeutic strategies. Nanostructured drugs have presented some advantages over the conventional medicines, such as slow, gradual and controlled release, increased bioavailability, and reduced side-effects, among others. In this study, in vitro antimicrobial activity of tea tree oil (TTO) nanoparticles against Paenibacillus species, including P. larvae and M. plutonius strains was evaluated. Minimal inhibitory concentration (MIC) in Mueller–Hinton or KSBHI broth by the microdilution method was assessed. TTO registered MIC values of 0.18–6.25%, while the MIC values obtained for the TTO nanoparticle were of 0.01–0.93%. The possible toxic effect of TTO and TTO nanoparticle has been assessed by the spraying application method in the concentrations higher than the MICs. Bee mortality was evident only in treatment with TTO and the TTO nanoparticles show no toxic effects after 7 days of observation. Our results showed for the first time that TTO nanoencapsulation presented a high activity against Paenibacillus species and M. plutonius strains showing that the use of nanotechnology may represent one alternative way for the treatment or prevention of AFB and EFB.