Phenotypic plasticity of a winter-diapause mechanism copes with the effects of summer global warming in an ectothermic predator.

To adapt to changes in temperature, animals tend to invest more energy in thermal tolerance to enhance survival, which can have simultaneous costs on plastic traits. Would a decrease in genetic variability, due to global warming, affect the ability of populations with existing metabolic regulatory mechanisms to cope with extreme temperatures? To address this question, we conducted a series of experiments based on the A1B scenario of global warming, assessing within-population genetic variance in (a) morphological traits, (b) metabolic rate allometries, and (c) survival of a winter-diapausing predator ectotherm. Our study focused on the lacewing species Chrysoperla pallida, using both exogamic and endogamic artificial genetic lines. We discovered that both lines use their winter-diapausing phenotype to adapt to summer extreme temperatures caused by extreme heating conditions, but the exogamic line is prone to express phenotypic plasticity in metabolic scaling, with a trade-off between body size and mandible size, i.e. larger individuals tended to develop smaller mandibles to better survive. These findings highlight the significance of substantial phenotypic plasticity and pre-existing metabolic regulatory mechanisms in enabling ectotherms to cope with potential extreme heating occurring in global warming.

The Influence of Planting Periods on Herbivore and Natural Enemy Abundance on Yellow Sticky Traps in Bt Maize Fields.

Knowledge of the insect densities during crop development is necessary for adopting appropriate measures for the control of insect pests and minimizing yield losses. Within integrated pest management programs, crop rotation has been carried out in recent years, but this current trend delays the planting period for Bt maize. The small amount of available information regarding the influence of sowing Bt maize early or late on the seasonal abundance of herbivores prompted us to study these aspects in two current common planting periods in northeastern Spain in 52 maize fields over three consecutive years. We sampled the fields planted on different dates with sticky yellow traps. Our results show that only the abundances of herbivore thrips, other than Frankliniella occidentalis, and Syrphidae were significantly different between the two planting periods. Moreover, when we performed yearly analyses, we found significant effects of the planting period on Coccinellidae and Chrysopidae in 2015 and on Aeolothrips sp. in 2016 and 2017. In most of the taxa, the abundance peaks in earlier growth stages, which is related to pollination (before or during). Only the abundances of Stethorus punctillum and Syrphidae peak later in the season. In addition, F. occidentalis, aphids, Syrphidae, and Coccinellidae registered higher abundance in fields sown in the late planting period. These results highlight the effects of sowing in different planting periods on insect dynamics in Bt maize and can be used to identify the abundance of certain pests and natural enemies in specific phenological stages of maize, which may allow producers to adopt better-integrated management and thus avoid reaching the level of economic damage.

Growth analysis of Amaranthus hypochondriacus L., in presence of living fences / Análisis del crecimiento de Amaranthus hypochondriacus L., en presencia de barreras vivas

The fragmentation and destruction of natural habitats for agriculture along with undiscriminated pesticide use represent the principal cause of biodiversity loss worldwide. To counteract for this agroecology tries to rescue the endogenous potential of agroecosystems to reach resilience and strengthen its reproduction at the biological level. For this it is used sustainable management technics, such as planing or conserving living fences. However, their efficacy within re-valued crops is still poorly known, as in the case of Amaranth crop. Here it is assessed the vegetative growth of Amaranthus hypochondriacus L., based on the proximity to native living fences at a small holder scale. It was compared three different systems, a natural area, a crop area with living fence, and a crop area without living fence. The results showed that A. hypochondriacus crop plants responded positively to the presence of native living fences, i.e., A. hypochondriacus plants grew bigger in the section nearest to adjacent vegetation, especially the panicle, suggesting edge effects. Though, the present study recorded for the first time that Amaranth crop plants have the potential to respond to the presence of native living fences (ecotone) positively affecting the growth of such a re-valued crop.

El fraccionamiento y/o destrucción de los hábitats naturales para el uso agrícola, y el uso indiscriminado de plaguicidas y agroquímicos, representan las causas más importantes en la pérdida masiva de diversidad biológica a nivel mundial. Para contrarestar estó, la agroecología trata de rescatar el potencial endógeno de los agroecosistemas locales, para alcanzar la autosuficiencia y fortalecer su reproducción a nivel biológico; haciendo uso de tecnicas de manejo sostenible como las barreras vivas, las cuales suponen beneficios para la agricultura, sin embargo, la eficiencia de éstas hacia los cultivos es poco conocida sobre todo en cultivos revalorizados como el Amaranto. En el presente estudio se evaluó el crecimiento vegetativo de Amaranthus hypochondriacus L., en función de la proximidad a barreras vivas nativas, a nivel de pequeña parcela, comparando tres sistemas diferentes, zona natural, zona con barrera viva y zona sin barrera. Los resultados mostrarón patrones de respuesta positiva por parte de las plantas de A. hypochondriacus hacia la presencia de barreras vivas nativas. Las plántas de A. hypochondriacus tienden a crecer más, cerca de la barrera, y de manera importante la panícula; sugieriendo la existencia de efectos de borde positivos. Así el presente estudio establece por primera vez que las plantas de amaranto tienen el potencial de responder a la presencia de barreras vivas (ecotono) impactando positivamente en el crecimiento vegetativo de dicha especie cultivada.