En México se siembran más de 100 variedades de chile (Capsicum annuum L.), es un cultivo altamente redituable y representa una actividad económica de importancia nacional. Actualmente, enfrenta graves problemas fitosanitarios por la presencia de enfermedades como la marchitez del chile, causada por un complejo de patógenos de suelo. Para el control de estas enfermedades, se utilizan fungicidas tóxicos y residuales, que contaminan el ambiente e inducen resistencia genética en los fitopatógenos. Por ello, es necesario buscar alternativas de control para solucionar este problema, por tanto, el objetivo de este trabajo fue evaluar el efecto antagónico de Trichoderma spp., contra los agentes causales de marchitez en confrontaciones in vitro mediante cultivos duales. El estudio se llevó acabo en 2016, en la Universidad Intercultural de Estado de Puebla, Huehuetla, Puebla, México. Se evaluaron tres aislamientos de Trichoderma provenientes de la rizósferas de árboles de aguacate, T. viride, T. harzianum y T. asperellum y tres aislamientos de los fitopatógenos P. capsici, F. oxysporum y R. solani obtenidos de las raíces de plantas de chile con síntomas de la marchitez. Los aislamientos se caracterizaron morfológicamente para su identificación. Los tres hongos antagonistas presentaron alto porcentaje de inhibición, T. asperellum mostró el 88.25%, T. viride 87.22% y T. harzianum con 87.8%. En las condiciones del estudio, T. asperellum, T. viride y T. harzianum, resultaron microorganismos antagónicos eficientes contra los fitopatógenos. Se sugiere realizar evaluaciones de biocontrol con estos aislamientos en invernadero y a campo abierto.

Charcoal rot is an emerging disease for peanut crops caused by the fungus Macrophomina phaseolina. In Mexico, peanut crop represents an important productive activity for various rural areas; however, charcoal rot affects producers economically. The objectives of this research were: (a) to identify and morphologically characterize the strain “PUE 4.0” associated with charcoal rot of peanut crops from Buenavista de Benito Juárez, belonging to the municipality of Chietla in Puebla, Mexico; (b) determine the in vitro and in vivo antagonist activity of five Trichoderma species on M. phaseolina, and (c) determine the effect of the incidence of the disease on peanut production in the field. Vegetable tissue samples were collected from peanut crops in Puebla, Mexico with the presence of symptoms of charcoal rot at the stem and root level. The “PUE 4.0” strain presented 100% identity with M. phaseolina, the cause of charcoal rot in peanut crops from Buenavista de Benito Juárez. T. koningiopsis (T-K11) showed the highest development rate, the best growth speed, and the highest percentage of radial growth inhibition (PIRG) over M. phaseolina (71.11%) under in vitro conditions, in addition, T. koningiopsis (T-K11) showed higher production (1.60 ± 0.01 t/ha⁻¹) and lower incidence of charcoal rot under field conditions. The lowest production with the highest incidence of the disease occurred in plants inoculated only with M. phaseolina (0.67 ± 0.01 t/ha⁻¹) where elongated reddish-brown lesions were observed that covered 40% of the total surface of the main root.

Bactericera cockerelli (Sulc) (Hemiptera: Triozidae) is one of the most economically important pests of potato, tomato, and peppers in Central America, Mexico, the United States, and New Zealand. Its control is based on the use of insecticides; however, recently, the potential of the eulophid parasitoid Tamarixia triozae (Burks) (Hymenoptera: Eulophidae) for population regulation has been studied. Because T. triozae is likely to be exposed to insecticides on crops, the objective of this study was to explore the compatibility of eight insecticides with this parasitoid. The toxicity and residual activity (persistence) of spirotetramat, spiromesifen, beta-cyfluthrin, pymetrozine, azadirachtin, imidacloprid, abamectin, and spinosad against T. triozae adults were assessed using a method based on the residual contact activity of each insecticide on tomato leaf discs collected from treated plants growing under greenhouse conditions. All eight insecticides were toxic to T. triozae. Following the classification of the International Organization of Biological Control, the most toxic were abamectin and spinosad, which could be placed in toxicity categories 3 and 4, respectively. The least toxic were azadirachtin, pymetrozine, spirotetramat, spiromesifen, imidacloprid, and beta-cyfluthrin, which could be placed in toxicity category 2. In terms of persistence, by day 5, 6, 9, 11, 13, 24, and 41 after application, spirotetramat, azadirachtin, spiromesifen, pymetrozine, imidacloprid, beta-cyfluthrin, abamectin, and spinosad could be considered harmless, that is, placed in toxicity category 1 (<25% mortality of adults). The toxicity and residual activity of some of these insecticides allow them to be considered within integrated pest management programs that include T. triozae.

Bactericera cockerelli es una de las plagas más importantes en solanáceas en México. Su manejo se basa en el uso de insecticidas y recientemente se ha explorado el uso del parasitoide Tamarixiatriozae dentro de un programa de MIP, por lo que el objetivo del presente trabajo fue explorar la compatibilidad de insecticidas con este parasitoide. En este trabajo se evaluó, en condiciones de laboratorio (25 ± 2 ºC, 60 ± 5% H.R.), la toxicidad de azadiractina, spinosad, imidacloprid y abamectina sobre T. triozae y B. cockerelli. Los cuatro insecticidas resultaron tóxicos tanto para el psílido como para el parasitoide, aunque el grado de toxicidad dependió de la especie, insecticida, estado biológico específico, dosis y forma en que los insectos se expusieron a los productos. De acuerdo a la IOBC, la abamectina y el spinosad fueron los productos más tóxicos (categoría 3), mientras imidacloprid y azadiractina presentaron niveles bajos de toxicidad (categoría 1). Las ninfas del psílido fueron más tolerantes a los insecticidas que los adultos y la toxicidad se incrementó cuando los insectos se sumergieron directamente en los productos. El imidacloprid a dosis de 1.0 L ha-1 aplicado directamente sobre las pupas nulificó la emergencia del parasitoide. Spinosad fue el producto más persistente para el psílido y abamectina para el parasitoide, el efecto de ambos perduró hasta los 29 días. Por tanto, en condiciones de laboratorio ningún insecticida mostró compatibilidad con el uso de T. triozae al ser aplicados de manera simultánea, ya sea porque no fueron efectivos contra B. cockerelli durante el tiempo y forma de exposición (azadiractina e imidacloprid) o porque fueron muy tóxicos al parasitoide (abamectina y spinosad). En este trabajo se discuten algunas de las posibilidades de la combinación de estas estrategias de control, particularmente se indica la importancia de evaluar los productos bajo condiciones de campo.

The insecticidal and repellent effect of essential oil isolated from fresh leaves of Porophyllum linaria on maize weevil was evaluated, as well as the effect on the grain germination after treated. In total, 28 constituents were identified by gas chromatography coupled with mass spectrometry accounting for 99.86% of whole essential oil. The main majority compounds were β-myrcene (41.94%), D-limonene (20.29%), and estragole (20.03%). Contact toxicity significantly increased with dose and time after treatment. With the 800 ppm (highest concentration), the mortality (%) obtained for the tenth and fifteenth day was 43 and 82%, respectively, whereas with 50 ppm (lowest concentration) 30% mortality was obtained at the end of the experiment (fifteenth day). At 15 d (end of the experiment), the LC₅₀ y LC₉₀ were obtained with values of 329.01 ± 44.35 y 1058.86 ± 117.76 ppm, respectively. For a concentration of 800 ppm, a selection index of zero was obtained, indicating the preference of the pest to the untreated maize (control). The maize grains germination test showed a significant reduction both in the length of hypocotyl and radicle of maize grain. So, in the highest dose, the hypocotyl and radicle length was 1.40 ± 0.34 and 9.14 ± 0.55 cm, respectively, whereas the control group registered 3.28 ± 0.39 and 13.02 ± 0.97 cm, respectively. This finding is promising since as it could result in the identification of botanical substances capable of suppressing maize weevil, Sitophilus zeamais development.

The present study determines the chemical composition of Schinus molle essential oil and its mortality and repellent effect on Bactericera cockerelli immature stage and Sitophilus zeamais adults. Twenty-four compounds were identified and the most abundant were o-Cymene (29.04), 1R-α-Pinene (15.52), camphene (14.00), and β-myrcene (11.54). On the fifth-instar psyllid nymph, the LC₅₀ and LC₉₀ at 48 h were 442.67 and 864.29 ppm, and for the fourth-instar were 273.41 and 534.67 ppm. The maize-weevil registered an LC₅₀ and LC₉₀ of 343.25 and 986.96 ppm for the fifteenth day. A selection index (Si) of 0.37 with 800 ppm was registered, showing the highest repellent activity, while with the lowest concentration (50 ppm), non-repellent activity was recorded. However, all concentrations above 100 ppm showed repellency against the maize weevil. The study reveals, for the first time, the essential oil’s insecticidal effects on the fourth and fifth nymphal stage of the potato/tomato psyllid B. cockerelli and the usefulness of the essential oil as a repellent against adult of S. zeamais. The Si effect on maize weevil was grouped into categories.