• Energy Research

Under predicted global climate change, species will be gradually exposed to warmer temperatures, and to a more variable climate including more intense and more frequent heatwaves. Increased climatic variability is expected to have different effects on species and ecosystems than gradual warming. A key challenge to predict the impact of climate change is to understand how temperature changes will affect species interactions. Herbivorous insects and their natural enemies belong to some of the largest groups of terrestrial animals, and thus they have a great impact on the functioning of ecosystems and on the services these ecosystems provide. Here we studied the life history traits of the plant-feeding insect Plutella xylostella and its specialist endoparasitoid Diadegma semiclausum, when exposed to a daily heat pulse of 5 or 10°C temperature increase during their entire immature phase. Growth and developmental responses differed with the amplitude of the heat pulse and they were different between host and parasitoid, indicating different thermal sensitivity of the two trophic levels. With a +5°C heat pulse, the adult parasitoids were larger which may result in a higher fitness, whereas a +10°C heat pulse retarded parasitoid development. These results show that the parasitoid is more sensitive than its host to brief intervals of temperature change, and this results in either positive or negative effects on life history traits, depending on the amplitude of the heat pulse. These findings suggest that more extreme fluctuations may disrupt host-parasitoid synchrony, whereas moderate fluctuations may improve parasitoid fitness.

Efforts to recycle organic wastes using black soldier fly (BSF) Hermetia illucens into high-nutrient biomass that constitutes a sustainable fat (biodiesel) and high-quality protein ingredient in animal feeds have recently gained momentum worldwide. However, there is little information on the most suitable rearing conditions for growth, development and survivorship of these flies, which is a prerequisite for mass production technologies. We evaluated the physiological requirements for growth and reproduction of H. illucens on two diets [spent grains supplemented with brewers' yeast (D1) and un-supplemented (D2)]. Development rates at nine constant temperatures (10 - 42°C) were fitted to temperature-dependent linear and non-linear day-degree models. Thereafter, life history table parameters were determined within a range of favourable temperatures. The thermal maximum (TM) estimates for larval, pre-pupal and pupal development using non-linear model ranged between 37.2 ± 0.3 and 44.0 ± 2.3°C. The non-linear and linear day-degree model estimations of lower developmental temperature threshold for larvae were 11.7 ± 0.9 and 12.3 ± 1.4 °C for D1, and 10.4 ± 1.7 and 11.7 ± 3.0 °C for D2, respectively. The estimated thermal constant of immature life stages development of BSF was higher for the larval stage (250±25 DD for D1 and 333±51 for D2) than the other stages evaluated. Final larval wet weight was higher on D1 compared to D2. The population growth rate was most favourable at 30-degree celsius (°C) with higher intrinsic rate of natural increase (r_m=0.127 for D1 and 0.122 for D2) and shorter doubling time (5.5 days for D1 and 5.7 days for D2) compared to the other temperatures. These results are valuable for the optimization of commercial mass rearing procedures of BSF under various environmental conditions and prediction of population dynamics patterns using computer simulation models. Supplement to: Chia, Shaphan Yong; Tanga, Chrysantus M; Khamis, Fathiya Mbarak; Mohamed, Samira Abuelgasim; Salifu, Daisy; Sevgan, Subramanian; Fiaboe, Komi K M; Niassy, Saliou; van Loon, Joop J A; Dicke, Marcel; Ekesi, Sunday (2018): Threshold temperatures and thermal requirements of black soldier fly Hermetia illucens: Implications for mass production. PLoS ONE, 13(11), e0206097

There is an increased interest for using insects, such as the black soldier fly, to treat surplus manure and upcycle nutrients into the food system. Understanding the influence that BSFL have on nutrient flows and nutrient losses during manure bioconversion is key for sustainability assessments. Here we quantified and compared nutrient balances, nutrient levels in residual materials and emissions of greenhouse gases and ammonia between manure incubated with black soldier fly larvae (BSFL) and manure without BSFL, during a 9-day experimental period. We obtained high analytical recoveries, ranging between 95 and 103%. We found that of the pig manure supplied, 12.5% of dry matter (DM), 13% of carbon, 25% of nitrogen, 14% of energy, 8.5% of phosphorus and 9% of potassium was stored in BSFL body mass. When BSFL were present, more carbon dioxide (247 vs 148 g/kg of DM manure) and ammonia-nitrogen (7 vs 4.5 g/kg of DM manure) emitted than when larvae were absent. Methane, which was the main contributor to greenhouse gas emissions, was produced at the same levels (1.3 vs 1.1 g/kg of DM manure) in both treatments, indicating the main role that manure microbial methane emissions play. Nitrous oxide was negligible in both treatments. The uptake of nutrients by the larvae and the higher carbon dioxide and ammonia emissions modified the nutrient composition of the residual material substantially relative to the fresh manure. Our study provides a reliable basis to quantify the environmental impact of using BSFL in future life cycle assessments.

Les insectes tels que la mouche soldat noire (FBS) sont un composant nutritif pour l'alimentation du bétail avec des niveaux élevés de protéines. Le FBS peut être élevé sur une large gamme de flux résiduels organiques. Cela permet une production locale dans le cadre d'une agriculture circulaire, découplant la production animale de l'importation de composants alimentaires coûteux, tels que la farine de poisson ou la farine de soja. L'élevage du FBS peut être fait par les petits exploitants agricoles, contribuant ainsi à leurs moyens de subsistance, à leur durabilité économique et à leur statut social. Les petits exploitants agricoles contribuent de manière importante à la sécurité alimentaire, qui est une condition préalable à une société stable. Dans les conflits armés, les petits exploitants agricoles sont généralement les premiers à souffrir. Dans les pays sortant d'un conflit, le développement agricole devrait se concentrer sur la restauration de la production alimentaire des petits agriculteurs, l'amélioration de leur position socio-économique, contribuant ainsi aux objectifs de développement durable 2 (faim zéro) et 16 (paix et justice). Ici, nous nous concentrons sur ces ODD avec un exemple de réintégration des ex-combattants en tant que petits producteurs d'insectes dans la Colombie post-conflit. Insectos como la mosca soldado negra (BSF) son un componente nutritivo para el ganado con altos niveles de proteínas. El BSF se puede criar en una amplia gama de corrientes residuales orgánicas. Esto permite la producción local dentro de una agricultura circular, desacoplando la producción ganadera de la importación de componentes alimenticios caros, como la harina de pescado o la harina de soja. La cría de BSF puede ser realizada por pequeños agricultores, contribuyendo así a su sustento, sostenibilidad económica y estatus social. Los pequeños agricultores contribuyen de manera importante a la seguridad alimentaria, que es un requisito previo para una sociedad estable. En los conflictos armados, los pequeños agricultores suelen ser los primeros en sufrir. En los países que se recuperan de un conflicto, el desarrollo agrícola debe centrarse en la restauración de la producción de alimentos por parte de los pequeños agricultores, mejorando su posición socioeconómica, contribuyendo así a los objetivos de desarrollo sostenible 2 (hambre cero) y 16 (paz y justicia). Aquí, nos centramos en estos ODS con un ejemplo de reintegración de excombatientes como pequeños productores de insectos en Colombia después del conflicto. Insects such as the black soldier fly (BSF) are a nutritious feed component for livestock with high protein levels. BSF can be reared on a wide range of organic residual streams. This allows for local production within a circular agriculture, decoupling livestock production from import of expensive feed components, such as fishmeal or soymeal. Rearing of BSF can be done by smallholder farmers, thus contributing to their livelihood, economic sustainability and social status. Smallholder farmers contribute importantly to food security, which is a prerequisite for a stable society. In armed conflicts, smallholder farmers are usually the first to suffer. In countries recovering from conflict, agricultural development should focus on restoring food production by smallholder farmers, improving their socio-economic position, thereby contributing to sustainable development goals 2 (zero hunger) and 16 (peace and justice). Here, we focus on these SDGs with an example of reintegration of ex-combatants as smallholder insect producers in post-conflict Colombia. الحشرات مثل ذبابة الجندي الأسود (BSF) هي عنصر تغذية مغذي للماشية ذات المستويات العالية من البروتين. يمكن تربية BSF على مجموعة واسعة من الجداول العضوية المتبقية. وهذا يسمح بالإنتاج المحلي داخل الزراعة الدائرية، وفصل الإنتاج الحيواني عن استيراد مكونات الأعلاف باهظة الثمن، مثل دقيق السمك أو دقيق الصويا. يمكن أن يقوم المزارعون أصحاب الحيازات الصغيرة بتربية صندوق الضمان الاجتماعي، مما يساهم في سبل عيشهم واستدامتهم الاقتصادية ووضعهم الاجتماعي. يساهم المزارعون أصحاب الحيازات الصغيرة بشكل كبير في الأمن الغذائي، وهو شرط أساسي لمجتمع مستقر. في النزاعات المسلحة، عادة ما يكون المزارعون أصحاب الحيازات الصغيرة أول من يعاني. في البلدان التي تتعافى من النزاع، ينبغي أن تركز التنمية الزراعية على استعادة الإنتاج الغذائي من قبل صغار المزارعين، وتحسين وضعهم الاجتماعي والاقتصادي، وبالتالي المساهمة في تحقيق هدفي التنمية المستدامة 2 (القضاء على الجوع) و 16 (السلام والعدالة). هنا، نركز على أهداف التنمية المستدامة هذه مع مثال على إعادة إدماج المقاتلين السابقين بصفتهم منتجين للحشرات من أصحاب الحيازات الصغيرة في كولومبيا ما بعد الصراع.

Summary Plants are commonly exposed to abiotic and biotic stresses. We used 350 Arabidopsis thaliana accessions grown under controlled conditions. We employed genome‐wide association analysis to investigate the genetic architecture and underlying loci involved in genetic variation in resistance to: two specialist insect herbivores, Pieris rapae and Plutella xylostella; and combinations of stresses, i.e. drought followed by P. rapae and infection by the fungal pathogen Botrytis cinerea followed by infestation by P. rapae. We found that genetic variation in resistance to combined stresses by drought plus P. rapae was limited compared with B. cinerea plus P. rapae or P. rapae alone. Resistance to the two caterpillars is controlled by different genetic components. There is limited overlap in the quantitative trait loci (QTLs) underlying resistance to combined stresses by drought plus P. rapae or B. cinerea plus P. rapae and P. rapae alone. Finally, several candidate genes involved in the biosynthesis of aliphatic glucosinolates and proteinase inhibitors were identified to be involved in resistance to P. rapae and P. xylostella, respectively. This study underlines the importance of investigating plant responses to combinations of stresses. The value of this approach for breeding plants for resistance to combinatorial stresses is discussed.

AbstractClimate change alters many environmental parameters with strong consequences for ecological interactions, from species interactions to community dynamics. Temperature is crucial in determining ecosystem dynamics, especially for those involving ectothermic species such as plants or insects. Phenotypic plasticity, the capacity of one genotype to produce different phenotypes in response to environmental conditions, is a common mechanism by which individuals adapt to changing environments and is observed in multiple traits. The capacity of genotypes to adapt to novel temperature conditions plays a crucial role in structuring ecosystem dynamics and species persistence in adverse conditions. It is well recognised that temperature in natural ecosystems fluctuates over multiple time scales (e.g., hour, day, season, year). These fluctuations can follow predictable patterns or be unpredictable, with different consequences for phenotypic plasticity and ecosystem dynamics. Among trophic interactions, host–parasitoid interactions represent a special case because of the intimate symbiosis of the parasitoid larvae with their host. Understanding how and to what extent phenotypic plasticity structures species’ ecological niches is of utmost importance in the context of rapid climate change. With a particular focus on host–parasitoid interactions, this review discusses the literature on the role of phenotypic plasticity in fluctuating environments, highlighting the role of temporal dynamics. While we discuss literature on phenotypic plasticity at large, this review emphasises the fundamental effects of extreme temperatures in driving biochemical rates underlying phenotypic plasticity.