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Secondary metabolites produced by the fermentation of Streptomyces avermitilis bacterium are powerful antiparasitic agents used in animal health, agriculture and human infection treatments. Avermectin is a macrocyclic lactone with four structural components (A1, A2, B1, B2), each of them containing a major and a minor subcomponent, out of which avermectin B1a is the most effective parasitic control compound. Avermectin B1a produces two homologue avermectins (B1 and B2) that have been used in agriculture as pesticides and antiparasitic agents, since 1985. It has a great affinity with the Cl-channels of the glutamate receptor, allowing the constant flow of Cl- ions into the nerve cells, causing a phenomenon of hyperpolarization causing death by flaccid paralysis. The purpose of this work was to gather information on the production of avermectins and their biocidal effects, with special emphasis on their role in the control of pests and phytopathogenic diseases. The literature showed that S. avermitilis is an important producer of macrocyclic lactones with biocidal properties. In addition, avermectin contributes to the control of ectoparasites and endoparasites in human health care, veterinary medicine and agriculture. Importantly, avermectin is a compound that is harmless to the host (no side effects), non-target organisms and the environment. [ABSTRACT FROM AUTHOR]

Copyright of Ecosistemas y Recursos Agropecuarios is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One of the important domestic insects that transmit many pathogens to the environment is the Periplaneta Americana. The control methods of this insect are often ineffective and have caused resistance in these insects. The purpose of the present study was to investigate the effects of contact and feeding lethality of titanium nanoparticles on Periplaneta Americana. In this study, different concentrations of nanoparticles were prepared for oral and contact treatments of Periplaneta Americana. Periplaneta Americana was treated by contact and oral methods with different concentrations of titanium oxide nanoparticles with three repetitions. The average percentage of insect mortality in different groups was compared by one-way analysis of variance and Duncan's test. Also, the average percentage of insect mortality on different days in each group was compared by analysis of variance with repeated observations. Oral treatment of Periplaneta Americana was more effective than contact treatment in concentrations of 15 and 21 percent on all days, but contact treatment was more effective than oral treatment on all days except the seventh day at a concentration of 25 percent. In general, oral treatment was more effective than contact treatment. With increasing doses and the passage of time, the mortality percentage of Periplaneta Americana due to contact and oral treatment with titanium dioxide nanoparticles increased significantly. According to the obtained results, the use of different nanoparticles, including titanium dioxide nanoparticles, can create a significant effect in controlling the Periplaneta Americana as a new method along with the previous methods. [ABSTRACT FROM AUTHOR]

Bactericera cockerelli is an economically relevant pest of solanaceous crops. The presence of leaf trichomes that certain wild species have constitutes important genetic resources for plant breeding programs in terms of resistance to pests. In this study, the influence of leaf trichomes of wild species and commercial tomato cultivars on the preference, development and fecundity of B. cockerelli was evaluated. The results showed that wild species were less preferred by the psyllid than commercial cultivars. Insects showed a lower settlement percentage in S. habrochaites compared to the other species. Regarding survival, the lowest percentage developed in S. habrochaites with 24% and S. arcanum with 40%. The lowest oviposition average was found in S. habrochaites with two eggs, which did not hatch, in addition to being the only species that showed the presence of glandular trichomes type IV (113.86 ± 48.1) and VIc (27.3 ± 2.3) per mm2, and its presence was negatively correlated with the number of perched adults. S. arcanum was another species that negatively influenced the behavior and development of the insects; however, these attributes were not due to the presence of trichomes. The defense mechanisms expressed by S. habrochaites and S. arcanum towards B. cockerelli can be used as a resource for gene introgression for the management of this pest by reducing its biological potential. [ABSTRACT FROM AUTHOR]

Warehouse pests cause losses in seed quality by physically damaging seeds, carrying other pathogens, and leaving residues of their consumption or their remains. Taking into account that warehouse pests have higher metabolism rates than seeds, in the present study, the viability of Sitophilus zeamais (Motschulsky & V.de, 1855) insects and the germination of corn seeds were evaluated for 93 and 180 days, respectively, under conditions of a partial vacuum (0.26 atm (atmosphere)), hermetic sealing, and air exchange. The partial vacuum environment (0.26 atm) did not negatively affect the germination of the seeds over a period of 180 days and resulted in the mortality of adult insects from the 4th day onwards; it also completely prevented physical damage to the seeds. The hermetic packaging did not negatively affect germination, but the insects remained active until day 34, and there was severe damage to the seeds used for their sustenance. Similarly, the gas exchange packaging did not affect germination, but the insects remained active until the last day of observation (93) and also caused severe damage to the seeds used for their maintenance. Partial vacuum (0.26 atm) storage represents a practical solution in certain conditions, for example, the short-term (6 months) storage of germplasms at room temperature (24–26 °C); it can also be useful in the storage and transfer of grains, with the possibility of eliminating or reducing the need for insecticide applications. [ABSTRACT FROM AUTHOR]

Copyright of Ecosistemas y Recursos Agropecuarios is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ecosistemas y Recursos Agropecuarios is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Universitaria is the property of Universidad de Guanajuato/Acta Universitaria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Investigación y Ciencia de la Universidad Autónoma de Aguascalientes is the property of Universidad Autonoma de Aguascalientes, Direccion General de Investigacion y Posgrado and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)