Dalbulus maidis (DeLong & Wolcott) (Hemiptera: Ciaadellidae) is the most important leafhopper vector of maize plant pathogens in the Americas. However, until now, no study has investigated the overwintering biology of its egg parasitoids. The objective in this study was to find egg parasitoids of D.maidis in perennial grass, volunteer maize, stubble, and drip-irrigated maize habitats in the winter season. Two-week-old D. maidis females were allowed to oviposit on young maize plants for 72 h under laboratory conditions. The oviposited healthy D.maidis eggs (sentinel eggs) on the young maize plants were exposed to natural parasitism maintained on perennial grasses, volunteer maize, and stubble 2 mo after the onset of winter, and on perennial grasses, volunteer maize, and drip-irrigated maize at the end of winter. The abundance of D. maidis adults in these habitats was also determined. Two months after the start of winter, D.maidis eggs were parasitized by the wasp Oligosita sp. from perennial grasses and volunteer maize, whereas at the end of winter, the eggs were parasitized by the wasps Oligosita sp. and Anagrus columbi Perkins from perennial grasses, volunteer maize, and drip-irrigated maize. Overall, more adult parasitoids of D. maidis eggs were found on perennial grasses. Adult corn leafhoppers were absent from perennial grasses at the end of winter; however, other Deltocephalinae leafhopper species were present, suggesting that egg parasitoids of D. maidis use another leafhopper host during winter. Furthermore, adults of five Deltocephalinae species were parasitized by dryinids and strepsipterans throughout the 2012–2013 winter in perennial grasses.

Little is known about the host-parasitoid interactions on the edges of crops during winter. Our objective was to determine the parasitoid species that attack nymphs and adults of leafhoppers and planthoppers, and evaluate the interactions that occur during winter on maize edges. Between January and June of 2014 and 2015 leafhoppers and planthoppers with evidence of parasitism by Dryinidae (Hymenoptera) were collected on grasses that grow in maize fields margins in Mexico and were maintained alive until parasitoid adult emergence. Dryinids such as Gonatopus huggerti (Olmi), Gonatopus mimoides (Perkins), Gonatopus breviforceps (Kieffer), and Gonatopus caraibicus (Olmi) were the most common parasitoids. They attacked several leafhopper species such as Dalbulus maidis (DeLong), Balclutha incisa (Matsumura), Exitianus picatus (Gibson), and Stirellus bicolor (Van Duzee). The connection of the net was of 31%. The presence of parasitoids in winter margins highlights the importance of conserving maize edges for biological control.

Homopteran vectors (e.g., leafhoppers) of plant pathogens are vessels for reproduction of cell wall‐free bacteria. These vectors also serve as hosts for larval parasitoid dipterans, hymenopterans, and strepsipterans. However, no study has explored the relationship among these wall‐free bacteria and parasitoid larvae within the insect host. We studied the corn stunt spiroplasma (CSS), Spiroplasma kunkelii Whitcomb (Mycoplasmatales: Spiroplasmataceae), a bacterium that originated from secondary symbionts that cause corn stunt disease in maize, Zea mays L., and its reproduction in the haemolymph of the corn leafhopper, Dalbulus maidis (Delong and Wolcott) (Homoptera: Cicadellidae). We also studied the dryinid parasitoid Gonatopus bartletti Olmi (Hymenoptera: Dryinidae), the larva of which feeds in the corn leafhopper haemolymph. Our results showed that when CSS and the wasp coexisted in D. maidis, the development of the parasitoid was not affected by S. kunkelii. Parasitoid development was successfully completed when leafhoppers acquired S. kunkelii before or after parasitism and when CSS had median (10 days) and long (20 days) incubation periods in the leafhopper before parasitization. The presence of S. kunkelii did not affect parasitoid development to the adult stage. However, polymerase chain reaction showed that the presence (survival) of S. kunkelii in the leafhopper was negatively affected by the parasitoid larva. Fewer leafhoppers had CSS before and after parasitization compared with leafhoppers that only acquired the CSS. This negative effect helps to explain the high parasitism rate by G. bartletti in D. maidis and the low presence of S. kunkelii in the corn leafhopper when CSS and the wasp parasitoid overlap throughout their geographic distribution. The parasitoid larva may negatively affect S. kunkelii by (1) producing antibacterial peptides that are toxic to CSS; (2) producing teratocytes that take nutrients from the host for larval development, but these nutrients are required by CSS; (3) affecting, indirectly, CSS through other symbiotic microorganisms; and (4) producing proteins with antibacterial activity that are present in the venom of the wasp parasitoid.

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Las múltiples transiciones hacia un escenario poscovid-19 marcan la agenda reciente de APEC. Si bien, la liberación comercial y la disminución de las barreras que impiden la Inversión Extranjera Directa en las economías de APEC siguen siendo temas prioritarios en la agenda de este mecanismo de cooperación, estos temas no son los únicos que se debaten al interior de APEC, ni son los mismos, de acuerdo con el contexto que operan. La complejidad del mundo y los retos que enfrenta la humanidad se reflejan en las prioridades, objetivos y planes de acción que desde APEC se proponen, bajo el espíritu del regionalismo abierto, con la intención de crear las condiciones que permitan un desarrollo sostenible. APEC impulsa una serie de propuestas con la intención de generar las condiciones para un desarrollo equilibrado y sostenible, que permita la inclusión, abata la brecha de género y limite o reduzca los efectos negativos que se generan al medio ambiente derivados de las actividades económicas. A su vez, invita a pensar en planes de acción para mejorar la conectividad en todas sus formas e impulsar la innovación, la ciencia y la tecnología. Este libro ofrece una serie de reflexiones desde una perspectiva multidisciplinar sobre los desafíos de APEC en el contexto de un mundo enmarcado por las complejas transiciones poscovid-19.