Alexander Gaione Costa

Many organisms compensate for environmental constraints on resources by exhibiting plastic foraging strategies. Nutrient-poor soils can generate bottom-up stoichiometric constraints that propagate across trophic levels, potentially altering consumer foraging behaviour. Soil phosphorus (P) limitation constrains aboveground productivity in Amazonian forests. However, whether ecosystem-level P limitation reaches higher trophic levels in ways strong enough to shape fine-scale foraging investment remains unclear. Here, we evaluated this question by analysing the web architecture of the orb-weaver spider Hingstepeira folisecens (Araneidae) across plots from a long-term factorial nutrient-addition experiment. Spiders are known to adjust web investment and architecture in response to nutritional constraints, generally increasing silk investment under resource limitation. Therefore, we hypothesized that if P limitation increases spider investment in capture threads or web structural traits to compensate for reduced resource availability, then P addition should reduce such investment. Consistent with this prediction, spiders invested ~15% less in capture threads in +P plots compared to −P plots. Since capture threads are costly and directly associated with energetic investment in web construction, this reduction indicates that spiders invest more energy in foraging under natural low-P levels, consistent with a compensatory response to reduced prey or energy acquisition. In contrast, capture area remained unchanged following P addition, suggesting that these spiders reduced silk investment while maintaining the same foraging area. This suggests that web area may be less plastic than silk investment under nutrient limitation. Higher investment in costly threads in low-P environments may indicate trade-offs, where P limitation can create energetic conflicts among foraging, defence, and/or reproduction. Together, our findings demonstrate that nutrient limitation at the base of Amazonian food webs is strong enough to shape predator foraging strategies. This provides evidence that behavioural plasticity may allow predators to cope with ecosystem-level nutrient limitation, linking stoichiometric constraints to trophic interactions.

Com o isolamento social imposto pela pandemia de COVID-19, os Planos de Estudos Tutorados (PETs) emergiram como a alternativa para dar continuidade ao ano letivo nas escolas públicas de Minas Gerais. Embora os PETs fornecessem orientações e planos de estudo mensais, não apresentavam aplicação de atividades experimentais. Visando promover a inclusão de práticas investigativas como material complementar aos PETs nas turmas de ensino médio, este trabalho utilizou as Tecnologias Digitais de Informação e Comunicação (TDIC) como aliadas no processo de construção do conhecimento. Para isso, foram desenvolvidos materiais contendo sugestões de experimentos em Matemática, Física, Biologia e Química, vídeos ilustrativos e a criação de um concurso online, incentivando os alunos a produzirem materiais audiovisuais sobre os temas propostos. O trabalho, refere-se a um estudo de caso de natureza qualitativa, alinhado a perspectiva da pesquisa-ação, contou com a participação de uma equipe multidisciplinar de professores do ensino médio e superior, discentes de graduação e pós-graduação da UEMG, além de estudantes do 1° e 2° anos do ensino médio regular da E.E. Presidente Tancredo Neves, todos do município de Frutal-MG. Os resultados apontaram que a ação instigou os estudantes a trabalharem atividades de ciência de maneira experimental, por meio de uma proposta interdisciplinar e contextualizada, combinando o método adotado pela Secretaria de Estado de Educação de Minas Gerais (SEE-MG) com as mídias digitais de maior utilização por parte dos adolescentes, como o Instagram e o YouTube. Palavras-chave: Ensino Remoto. TDIC. Tendências Educacionais. Experimentação. Abstract With the social isolation imposed by the COVID-19 pandemic, Tutored Study Plans (PETs) emerged as an alternative to continue the school year in public schools in Minas Gerais. Although PETs provide guidance and monthly study plans, they do not include the application of experimental activities. Aiming to promote the inclusion of investigative practices as complementary material to PETs in high school classes, this work used Digital Information and Communication Technologies (TDIC) as allies in the knowledge-construction process. To this end, materials were developed containing suggestions for experiments in Mathematics, Physics, Biology, and Chemistry, illustrative videos and the creation of an online competition, encouraging students to produce audiovisual materials on the proposed themes. The work is a case study of a qualitative nature, aligned with the perspective of action research, involving the participation of a multidisciplinary team of secondary and higher education teachers, undergraduate and postgraduate students from UEMG, in addition to students in the 1st and 2nd years of regular high school at E.E. Presidente Tancredo Neves, all from the municipality of Frutal-MG. The results showed that the action encouraged students to engage in science activities in an experimental way, through an interdisciplinary and contextualized proposal, combining the method adopted by the State Department of Education of Minas Gerais (SEE-MG) with digital media most widely used by adolescents, such as Instagram and YouTube. Keywords: Remote learning. TDIC. Educational trends. Experimentation.

Strategies to invade and exploit hosts for survival are an essential part of the parasitic lifestyle. Species of the Polysphincta genus group (Hymenoptera: Ichneumonidae), which utilize spiders as hosts, are examples of parasitoids that present several behavioral strategies in host immobilization and egg laying. In this study, we characterized the oviposition behavior of the Darwin wasp Hymenoepimecis cameroni Townes, 1966 (Hymenoptera: Ichneumonidae) on their host spider, performed the taxonomic description of the female, and redescribed the male parasitoid. We observed eight H. cameroni females endeavoring to parasitize young Leucauge volupis (Keyserling, 1893) spiders. Each female made up to 12 successive attempts at oviposition, totaling 36 observed attacks, with only two successful attacks. The main oviposition behavior of H. cameroni individuals consists of flying close to the web and performing a direct attack on the spider, which often results in the spider escaping into the vegetation. We observed that in seven events where the spiders fled into the vegetation, the individuals of H. cameroni adopted a second strategy, which consisted of hanging from the hind legs in the web hub. This observation showed that the females of H. cameroni have the ability to modulate the oviposition strategy after a failure in the initial attack. The pattern observed for the attack of H. cameroni indicates that the ability to adjust the approach could be specific to the behavioral habits of L. volupis.