ABSTRACT Plant extracts are a great source of molecules with insecticidal activity and are used to control pests in various crop production systems. In this study, we evaluated the aphidicidal properties in vitro of the n-hexane extract of leaves of castor-bean (Ricinus communis L.; Euphorbiaceae) at different concentrations (0.5, 1.0, 2.5, 5.0 and 10 kg m-3) against apterous adults of corn leaf aphid (Rhopalosiphum maidis Fitch) and the yellow sugarcane aphid (Sipha flava Forbes). The observed effects were dose-dependent, and the highest concentration evaluated (10 kg m-3) caused 82% mortality in R. maidis and 79% in S. flava. To identify chemical compounds, present in the extract we used mass gas chromatography, identifying 16 compounds. Palmitic acid was the major compound, with 45.34% abundance. The data obtained indicate the existence of insecticidal compounds in the castor-bean n-hexane extract, which could be used as an alternative bioinsecticide in the integrated management of these two aphid species.

ABSTRACT Azotobacter vinelandii is a Gram negative that undergo a morphological and physiological differentiation process to form cysts resistant to desiccation. The main components of a cyst are alkylresorcinols (ARs), phenolic lipids of 21 to 23 C. These lipids are homologous to plant ARs, where they have been reported to have antifungal properties. The objective of this study was to evaluate the antifungal capacities of vegetative cells and cysts of A. vinelandii AEIV. The cysts were visualized by optical microscope and the detection of ARs was performed by thin layer chromatography. Antagonism bioassay were carried out between vegetative cells and cysts against Fusarium brachygibbosum, Aspergillus niger and Colletotrichum gloeosporioides. We confirmed the induction of cysts and the presence of ARs of A. vinelandii AEIV. We observed that using 1×103 cysts reduced up to 76.3% (p < 0.05) the growth of the three phytopathogenic fungi and this result was not observed when using vegetative cells or the strain blocked in the synthesis of ARs. This shows that the cysts exert an antagonistic effect on phytopathogenic fungi and do so through the ARs, considering the development of an effective strategy to control pests in fungi that affect postharvest fruits.

RESUMO A doença manchada de vinagreira causada por Corynespora cassiicola afeta a produção de cálice no México. O objetivo deste estudo foi avaliar vinte e dois genótipos de vinagreira contra C. cassiicola em casa de vegetação. Com base nas área abaixo da curva de progresso da doença (AACPD) foi possível detectar genótipos suscetíveis, tolerantes e resistentes. Dada a incidência nas folhas, os genótipos suscetíveis foram Conpoz, Sudlaz, Morcot e Sudigua (valores de AACPD 7379,2 a 5891,7); tolerantes foram Conayu e Chinxal (AACPD 1341,6 e 1313,2). Enquanto isso, pela severidade nas folhas, os suscetíveis foram Sudigua, Conpoz e Morena2 (AACPD de 788,4 a 436,3); tolerantes foram Almatech, Crioxal, Rojatec e Conayu (37,7 a 28,76 de AACPD). Enquanto, avaliando a incidência em cálices, genótipos suscetíveis foram; Morena2, Morena, Conpoz, Descop e Chinayu (AACPD de 6572,1 a 2319,4); para a gravidade suscetível foram Morena2, Descop, Morena, Cabxal, Chinayu e Conpoz (AACPD de 3355,4 a 779,2). A incidência e severidade nos cálices detectaram genótipos resistentes, que foram Almatech, Criolaz2, Criocot, Criolaz, Rojatec, Criopoz, Crioxal, Chinxal e Conayu (0,0 de AACPD). Neste estudo, foram detectados genótipos tolerantes e resistentes à mancha foliar e cálice causada por C. cassiicola em vinagreira.

ABSTRACT Roselle spot caused by Corynespora cassiicola affects calyx production in Mexico. The aim of the present study was to evaluate twenty-two roselle genotypes against C. cassiicola under greenhouse conditions. The area under the disease progress curve (AUDPC) was used to detect susceptible, tolerant and resistant genotypes. Considering the incidence in leaves, susceptible genotypes were Conpoz, Sudlaz, Morcot and Sudigua (AUDPC values of 7379.2 to 5891.7); tolerant genotypes were Conayu and Chinxal (AUDPC 1341.6 and 1313.2). Based on the severity in leaves, susceptible genotypes were Sudigua, Conpoz and Morena2 (AUDPC from 788.4 to 436.3); tolerant genotypes were Almatech, Crioxal, Rojatec and Conayu (37.7 to 28.76 AUDPC). Assessment of the incidence in calyces indicated that susceptible genotypes were Morena2, Morena, Conpoz, Descop and Chinayu (AUDPC from 6572.1 to 2319.4); for the severity in calices, susceptible genotypes were Morena2, Descop, Morena, Cabxal, Chinayu and Conpoz (AUDPC from 3355.4 to 779.2). Incidence and severity on calyces evidenced resistant genotypes, which were Almatech, Criolaz2, Criocot, Criolaz, Rojatec, Criopoz, Crioxal, Chinxal and Conayu (0.0 AUDPC). In the present study, tolerant and resistant genotypes were detected to leaf and calyx spot caused by C. cassiicola in roselle.

Abstract Due to the lack of knowledge of pathogenic bacteria to Melanaphis sacchari, the objective of this work was to evaluate the pathogenicity of bacterial strains against this aphid. In vitro bioassays were carried out at the Autonomous University of Guerrero in 2019. By intake in a contaminated diet, four strains were evaluated in two treatments of 10 and 100 µg ml-1 of total protein. Bioassays showed that the strains were pathogenic to the aphid, resulting in mortality at 48 h of between 35 ±8% to 63 ±12% at a concentration of 10 µg ml-1. While, at a concentration of 100 µg ml mortality was around 48 ±4% to 90 ±7%. The most virulent strains against the aphid at a concentration of 10 µg ml-1 were ETH-109 and ETH-117, resulting in mortality of 58 ±8% and 63 ±12%, respectively. Whereas, to the concentration of 100 µg ml-1 the most virulent strain was ETH-109 causing mortality of 90 ±7%, followed by the ETH-117 strain with 73 ±5% of dead aphids.

Resumen Debido a la falta de conocimiento de bacterias patógenas a Melanaphis sacchari, el objetivo de este trabajo fue evaluar la patogenicidad de cepas bacterianas contra este áfido. En la Universidad Autónoma de Guerrero en 2019 se llevaron a cabo los bioensayos in vitro. Mediante ingesta en dieta contaminada, se evaluaron cuatro cepas en dos tratamientos de 10 y 100 µg ml-1 de proteína total. Los bioensayos demostraron que las cepas fueron patógenas al áfido, ocasionando una mortalidad a las 48 h de entre el 35 ±8% al 63 ±12% a una concentración de 10 µg ml-1. En tanto que, a una concentración de 100 µg ml-1 la mortalidad fue de alrededor del 48 ±4% al 90 ±7%. Las cepas más virulentas contra el áfido a una concentración de 10 µg ml-1 fueron la ETH-109 y ETH-117, ocasionando una mortalidad de 58 ±8% y 63 ±12%, respectivamente. Mientras que, a la concentración de 100 µg ml-1 la cepa más virulenta fue la ETH-109 causando una mortalidad de 90 ±7%, seguida de la cepa ETH-117 con un 73 ±5% de áfidos muertos.

Resumen La situación de salud y percepción de riesgos de las comunidades indígenas se mide por el grado sociodemográfico y estudio etnográfico. Nuestra población en estudio “El Calvario” es la única comunidad indígena Mixteca de Chilpancingo, Guerrero, conformada por 21 familias que se dedican a la agricultura, producción de maguey y mezcal, y elaboración de algunas artesanías de palma. El objetivo fue estudiar las condiciones de Calidad de Vida y percepción de riesgos en dos grupos vulnerables adultos y niños. En el caso de los adultos, se hizo por encuestas y en el caso de los niños se usó el dibujo. En los habitantes se perciben en riesgos de salud y de perder su identidad indígena, debido a que solo hablan su lengua materna los adultos, no saben leer y ni escribir. Así mismo, es inminente el riesgo de sufrir daños materiales debido a que las viviendas no son adecuadas. La migración de jóvenes, la perdida de cultura, el padecer enfermedades metabólicas debido a la dieta alta en refrescos. Así mismo, los niños expresaron las deficiencias educativas. Finalmente, la población en general se encuentra olvidada por los organismos de gobierno actuales, en riesgo sanitario, y de perdida de cultura ya que los jóvenes migrarán a otros lugares a buscar nuevas oportunidades. Es un fuerte llamado de atención a la sociedad ya que, de no actuar en consecuencia con dicha problemática, se perdería la única comunidad Mixteca en Chilpancingo, Guerrero.

Abstract The health situation and risk perception of indigenous communities is measured by sociodemographic grade and ethnographic study. Our study population "El Calvario" is the only Mixtec indigenous community in Chilpancingo, Guerrero, made up of 21 families that are dedicated to agriculture, production of maguey and mezcal, and making some palm handicrafts. The objective was to study the conditions of Quality of Life and risk perception in two vulnerable groups, adults and children. In the case of adults, it was done through surveys and in the case of children, drawing was used. The inhabitants are perceived as being at risk of health and of losing their indigenous identity, because only adults speak their mother tongue, they do not know how to read and write. Likewise, the risk of suffering material damage is imminent due to the inadequate housing. The migration of young people, the loss of culture, suffering from metabolic diseases due to a diet high in soft drinks. Likewise, the children expressed educational deficiencies. Finally, the general population is forgotten by current government agencies, at risk of health, and loss of culture as young people will migrate to other places to seek new opportunities. It is a strong call for attention to society since, if it does not act accordingly, the only Mixtec community in Chilpancingo, Guerrero, would be lost.

Summary The mining activity has left mine tailings with high quantities of heavy metals and metalloids. Due their extreme toxicity, they represent a hostile environment for microbial colonization; however, there are metalotolerant bacteria in these mining wastes, and this is attributed to mechanisms of bioaccumulation and biotransformation of metals. The native bacteria from El Fraile mine tailings have developed adaptation mechanisms that allow them to persist in a toxic environment, thus, the objective of this study was to isolate and identify bacteria with the ability to tolerate, bioaccumulate or biotransform heavy metals. Our study was based on descriptive observations, we isolated 141 strains from water, leachate, soil, and rhizosphere and stems of plants from El Fraile mine tailings, Guerrero, Mexico. Bacterial tolerance was determined by the minimum inhibitory concentration in different metallic salts, the capacity of bioaccumulation of Ag, Pb, Cr, and Cd, and by the biotransformation of As (III) and Cr6+; in addition, representative bacteria were identified using 16S rRNA gene sequences. The results of the 141 strains analyzed showed ascending tolerance to Cd2+ 2 mM, Cu2+ 5 mM, Pb2+ 9 mM, Zn2+ 9 mM, Ag2+ 10 mM, As3+ 30 mM, and As5+ 45 mM. Only 9.24 and 39% of the strains bioaccumulated Zn2+, Pb2+ and Ag2+. In regard to biotransformation, 9% oxidized As3+ to As5+, and 7 and 24% reduced As5+ to As3+ and Cr6+ to Cr3+, respectively. The genera that prevailed were Chryseobacterium sp., Staphyloccoccus sp., Stenotrophomonas sp., Acinetobacter sp., Bacillus sp., Serratia sp., and Enterobacter sp. These results showed that in El Fraile mine tailings, there are bacterial strains capable of bioaccumulating and biotransforming heavy metals and metalloids; therefore, further studies must be conducted to know their potential in the processes of bioremediation of areas polluted with metals.

Resumen La actividad minera ha dejado depósitos de jales ricos en metales pesados y metaloides. Por su toxicidad extrema, representan un ambiente hostil para la colonización microbiana; sin embargo, en estos residuos mineros existen bacterias metalotolerantes y esto se atribuye a mecanismos que destacan la bioacumulación y biotransformación de metales. Por lo tanto, las bacterias nativas que viven alrededor de los jales El Fraile, han desarrollado mecanismos de adaptación que las hace persistente en un ambiente tóxico; por tal motivo, el objetivo de este trabajo fue aislar e identificar bacterias capaces de tolerar, bioacumular o biotransformar metales pesados y metaloides. El estudio fue observacional descriptivo y se logró aislar 141 cepas de agua, lixiviados, suelo, rizosfera y tallos de plantas de los jales El Fraile, Guerrero, México. Se determinó tolerancia por concentración mínima inhibitoria en distintas sales metálicas, capacidad de bioacumulación de Ag, Pb, Cr, Cd y biotransformación de As (III) y Cr6+; algunas bacterias se identificaron mediante la secuencia del gene 16S ARNr. Los resultados de las 141 cepas analizadas mostraron tolerancia ascendente a Cd2+ 2 mM, Cu2+ 5 mM, Pb2+ 9 mM, Zn2+ 9 mM, Ag2+ 10 mM, As3+ 30 mM y As5+ 45 mM. Solo 9.24 y 39% de las cepas bioacumularon Zn2+, Pb2+ y Ag2+. En la biotransformación solo 9% oxidaron As3+ a As5+, 7 y 24% redujeron As5+ a As3+ y Cr6+ a Cr3+, respectivamente. Los géneros que prevalecieron fueron Chryseobacterium sp., Staphyloccoccus sp., Stenotrophomonas sp., Acinetobacter sp., Bacillus sp., Serratia sp., y Enterobacter sp. Por lo tanto, existen cepas bacterianas en la zona minera El Fraile capaces de bioacumular y biotransformar metales pesados y metaloides; por lo que es necesario realizar más estudios que permitan conocer su potencial en los procesos de biorremediación de sitios contaminados con metales.

Abstract. In recent years, Corynespora cassiicola induced spotted of roselle threatens calyx production. The objective was to determine if some bacterial strains inhibit the development of C. cassiicola in vitro and under biospace conditions. The inhibition of development was due to the dual confrontation of the bacteria: food (20), amphibian skin (41), tailings (22), air (seven) and rhizosphere (10) against the fungus. Plants of jamaican “Creole” variety were sown and artificially inoculated with C. cassiicola. From the beginning of symptoms of the disease, the selected bacterial strains with the highest percentage of inhibition were inoculated. AUDPC was evaluated. Only seven strains inhibited the development of the fungus in vitro from 62.7 to 100%: Klebsiella pneumoniae (M10-1 and M10-10), Acinetobacter lwoffii (A5), Sphingomonas paucimobilis (NF21), Serratia marcescens (M13ACD), S. liquefaciens (M8ACD) and Acinetobacter sp. (5H2). Regarding leaf severity, the M10-1 and M10-10 strains reduced AUDPC by 9.5 and 12.6%, respectively, followed by NF21 (AUDPC 14.5), the control registered the highest levels (AUDPC 45.7). For the severity in calyces, the AUDPC analyzes of all the strains exercised control by reducing severity levels (17.1-8.6 AUDPC).

Resumen. En años recientes, el manchado de la jamaica inducido por Corynespora cassiicola amenaza la producción de cálices. El objetivo fue determinar si algunas cepas bacterianas inhiben el desarrollo de C. cassiicola in vitro y bajo condiciones de bioespacio. La inhibición del desarrollo fue por confrontación dual de las bacterias: alimentos (20), piel de anfibios (41), jales mineros (22), aire (siete) y rizosfera (10) contra el hongo. Se sembraron plantas de jamaica variedad “criolla” y se inocularon artificialmente con C. cassiicola, a partir del inicio de síntomas de la enfermedad se inocularon las cepas bacterianas seleccionadas con mayor porcentaje de inhibición. Se evaluó la ABCPE. Solo siete cepas inhibieron del 62.7 al 100% el desarrollo del hongo in vitro: Klebsiella pneumoniae (M10-1 y M10-10), Acinetobacter lwoffii (A5), Sphingomonas paucimobilis (NF21), Serratia marcescens (M13ACD), S. liquefaciens (M8ACD) y Acinetobacter sp. (5H2). En relación a la severidad en hojas las cepas M10-1 y M10-10 redujeron el ABCPE en un 9.5 y 12.6%, respectivamente, seguido de NF21 (14.5 de ABCPE), el control registró los mayores niveles (45.7 de ABCPE). Para la severidad en cálices, los análisis del ABCPE de todas las cepas ejercieron control al reducir niveles de severidad (17.1-8.6 ABCPE).