The maize weevil (Sitophilus zeamais Motschulsky) is one of most important pest of stored seeds worldwide, but its current control method is based on the use of synthetic insecticides, usually leading to undesirable problems such as insecticide residues on treated food, human intoxications, and insect resistance development. Therefore the search of friendly alternative methods is required. The aim of this study was to assess, under laboratory conditions, the insecticidal properties of Peumus boldus Molina, Laurelia sempervirens (Ruiz & Pav.) Tul., and Laureliopsis philippiana (Looser) Schodde essential oils against S. zeamais. The phytochemical analysis of the three essential oils showed 1,8-cineole, safrole and methyleugenol as the common components; all of them documented with insecticidal activity from essential oils from other plant species. The highest toxicity (100% mortality) of these three oils acting as a contact insecticide was observed at 24 h exposure at 4% concentration. The estimated LC50 values for P. boldus, L. sempervirens, and L. philippiana were 0.37, 1.02, and 0.28 μL g-1, respectively. Peumus boldus exhibited the highest fumigant activity with 100% adult mortality at 30 μL oil L-1 air. At ≥ 0.5% (v/w) concentration, all essential oils showed repellent activity. These three essential oils showed a promissory insecticidal activity against the maize weevil.

Black Sigatoka is the main constraint to banana production worldwide, and epidemic outbreaks are continuously causing huge losses. Successful management of diseases requires a profound knowledge of the epidemiological factors that influence disease dynamics. Information regarding alternative hosts of Pseudocercospora fijiensis, the causal agent, is still very scarce. To date, only Heliconia psittacorum has been reported as an alternative plant host, and we hypothesized that other plants can house P. fijiensis. In the present report, ten plant species with suspicious leaf spots were collected inside and around commercial banana crops in Mexico. Diagnostic PCR gave positive amplification for six of these plant species, and DNA sequencing confirmed the presence of the pathogen in four. This is the first report of the presence of P. fijiensis in unrelated plants and it represents a breakthrough in the current knowledge of black Sigatoka. This finding is very important given the polycyclic nature of this disease whose successful management requires the control of initial inoculum to minimize epidemic outbreaks. The results presented herein can be used to introduce innovations in integrated black Sigatoka management programs to reduce initial inoculum, and help the international initiative to reduce the use of fungicides in banana production.

Vriesea heliconioides (Kunth) Hook. ex Walp es una bromelia que posee inflorescencias de brácteas rojas y pétalos blancos que le otorgan amplio potencial hortícola. Para su aprovechamiento comercial es necesario desarrollar protocolos de propagación eficientes que desalienten la extracción de su hábitat natural. Los objetivos del presente estudio fueron definir las condiciones óptimas para la germinación in vitro de semillas, determinar su viabilidad y regenerar plantas por organogénesis. Las semillas se sembraron en el medio de Murashige y Skoog (MS) completo o a la mitad de su concentración de sales para evaluar la germinación. Otras semillas se conservaron durante dos años a 10 ºC o a temperatura ambiente para estimar su viabilidad. Para inducir la organogénesis, plántulas obtenidas in vitro se cultivaron en el medio MS suplementado con distintas concentraciones de 6-bencilaminopurina (BAP, 5-15 μM) y ácido α-naftalenacético (ANA, 1 y 2 μM). Se alcanzó una germinación de 100 % de las semillas en el medio MS a la mitad de concentración de sales. La viabilidad de las semillas se puede mantener hasta por dos años conservándolas a 10 ºC, aunque ésta se reduce gradualmente hasta llegar a 86 % después de este tiempo. La organogénesis se observó en el medio MS adicionado con 10 μM de BAP y 1 μM de ANA, en el que se formaron 6.8 brotes por explante después de 12 semanas. La multiplicación de los brotes se obtuvo en las mismas concentraciones de reguladores de crecimiento usadas en la etapa de inducción. El alargamiento y enraizamiento de plantas se logró en el medio MS a la mitad de concentración de sales suplementado con 1 μM de ácido giberélico. La aclimatación de las plantas fue eficiente en fibra de coco y corteza con tasas de supervivencia de 95 y 93 %, respectivamente.