Robert A. Raguso

Research on butterflies has uncovered a conserved “toolkit” of genes for color pattern development and evolution. One of these genes is optix , a homeobox transcription factor that regulates ommochrome and melanin pigmentation, as well as structural coloration, in nymphalid butterflies. It remains unclear, however, whether optix plays any roles in color patterning outside of the Nymphalidae. We used CRISPR‐Cas9 to disrupt optix in the tobacco hornwormmoth Manduca sexta and observed a dramatic abdominal pigmentation phenotype, where orange pigmentation was replaced by black eumelanin. Chemical assays suggest that the orange pigment is not an ommochrome, indicating that optix modulates an alternative, uncharacterized pigment pathway in M. sexta . RNA‐seq and chemical analyses of orange and black abdominal scales lead us to speculate that the orange pigment may be a type of melanin, perhaps N‐β‐alanyldopamine (NBAD) sclerotin. Our results suggest that optix plays a deeply ancestral role in pigment regulation in Lepidoptera, and demonstrates evolutionary flexibility in how it interfaces with pigment chemistry across moths and butterflies.

Research on butterflies has uncovered a conserved "toolkit" of genes for color pattern development and evolution. One of these genes is optix , a homeobox transcription factor that regulates ommochrome and melanin pigmentation, as well as structural coloration, in nymphalid butterflies. It remains unclear, however, whether optix plays any roles in color patterning outside of the Nymphalidae. We used CRISPR-Cas9 to disrupt optix in the tobacco hornwormmoth Manduca sexta and observed a dramatic abdominal pigmentation phenotype, where orange pigmentation was replaced by black eumelanin. Chemical assays suggest that the orange pigment is not an ommochrome, indicating that optix modulates an alternative, uncharacterized pigment pathway in M. sexta . RNA-seq and chemical analyses of orange and black abdominal scales lead us to speculate that the orange pigment may be a type of melanin, perhaps N-β-alanyldopamine (NBAD) sclerotin. Our results suggest that optix plays a deeply ancestral role in pigment regulation in Lepidoptera, and demonstrates evolutionary flexibility in how it interfaces with pigment chemistry across moths and butterflies.

Plants are often attacked by multiple insect herbivores throughout their lifetime. Early‐arriving herbivores play a critical role in shaping plant responses, which in turn affect subsequent interactions. Later‐arriving herbivores can exploit damaged plants, but their role in modifying interactions and plant performance remains unclear. Thus, it is important to examine host plant preferences in late‐arriving herbivores, the cues guiding their behaviour, and the consequences of multiple herbivores. We examined interactions between two insect herbivore specialists, Acalymma vittatum (Coleoptera: Chrysomelidae) and Anasa tristis (Hemiptera: Coreidae), which often overlap in sequence on shared Cucurbitaceae host plants. We characterized natural succession patterns, identified the cues influencing early‐ and late‐arriving herbivores, and tested the preference–performance hypothesis by determining whether the field‐identified cues driving A. tristis attraction and oviposition predicted improved offspring performance on plants previously colonized by A. vittatum . Finally, we investigated how A. vittatum ‐mediated recruitment of A. tristis influenced plant growth and reproductive traits by manipulating herbivory from both species in field experiments. Field patterns showed that the presence, abundance, and oviposition behaviour of the late‐arriving herbivore, A. tristis , were strongly influenced by the presence and feeding activity of the early‐arriving herbivore, A. vittatum , but only on plants in the genus Cucurbita . In both choice and no‐choice bioassays, A. tristis adult females preferentially selected seedlings with active A. vittatum herbivory, and first‐instar hatchlings exhibited 28% greater growth on seedlings previously damaged by A. vittatum . A. tristis adult females did not respond to A. vittatum aggregation pheromone (chemical cue indicative of herbivory) in short‐range choice tests, nor to non‐ Cucurbita seedlings, regardless of prior herbivory. Field experiments showed that successive herbivory by A. vittatum and A. tristis significantly altered plant reproductive traits, delaying anthesis and reducing male flower and fruit production compared to control plants and those exposed only to A. vittatum . However, crop variety influenced the magnitude of these effects. Together, these findings demonstrate that early‐arriving herbivores induce plant responses that increase the abundance of subsequent herbivores, with cascading negative effects on plants, compounding the effects of these herbivores.

Eusociality, a major transition in evolution, is characterized by reproductive division of labour between queens and workers. Queen pheromones (QPs) maintain this division and inhibit worker reproduction across diverse lineages. Although QPs evolved repeatedly, it is unclear whether they evolved as honest signals of queen fecundity, as manipulative agents of chemical control, or both. If they function as honest signals, QPs may facilitate colony formation by signalling the relative benefits of cooperative versus independent nesting to behaviourally flexible kin when eusociality is facultative. Here, we identify the first QP to our knowledge from a facultatively eusocial species, the sweat bee Megalopta genalis, in which solitary nesting, social nesting and worker helping are plastic traits. The QP blend induces subordinate behaviour and inhibits worker investment in reproduction when presented in a natural context. QP levels are elevated in social-nesting queens relative to solitary reproductives; they forecast oviposition rates and worker indirect fitness gains and they predict the retention of female offspring as workers. QP components derive from oogenic nutrients, potentially enforcing signal honesty. Our findings indicate that QPs can mediate cooperative behaviour even when eusociality is incipient and facultative, supporting their origin as honest signals that may stabilize the emergence and elaboration of eusociality.

Plant–pollinator interactions structure ecological communities and represent a key component of ecosystem functioning. Pollination networks are expected to be more diverse and specialised in the tropics, but pollination ecology in these regions has been understudied in comparison to other areas. We reviewed research on pollination in the tropical Andes, one of the major biodiversity hotspots on Earth, where the uplift of mountains and past climate have resulted in spatiotemporally distinct species interactions. We found 1010 scientific articles on pollination in the Andes, of which 473 included or were carried out in tropical regions. The number of publications on pollination ecology in the tropical Andes has increased exponentially, with Colombia having the most articles, followed by Ecuador and Peru, and with Bolivia and Venezuela having notably fewer studies. More research has been carried out in humid montane forests and agricultural landscapes, and it has predominantly focused on describing diversity of species and interactions while neglecting analyses on the resilience and adaptability of pollinating systems, even though the Andean region is particularly susceptible to the effects of climate change and continues to undergo land conversion and degradation. Remarkably few studies have incorporated local knowledge, thus ignoring connections to human livelihoods and communities. A phytocentric perspective has been predominant, with fewer studies focusing directly on pollinators and a notable lack of articles with a holistic approach to the study of pollination across taxonomic groups at the community or ecosystem level. We propose that future research adopts a cross‐scale approach that considers the complexity of the ecological contexts in which plant–pollinator interactions occur, and incorporates long‐term monitoring with broader multilayer networks and molecular tools, experiments focused on ecophysiology and behaviour, animal telemetry, process‐modelling approaches and participatory science. A stronger field driven by interdisciplinary collaborations will contribute to knowledge about pollination at a global scale, as well as increase our understanding of the diversity and resilience of pollination interactions in this region, thus improving our capacity to predict and avoid ecosystem collapses.

Summary: Flowers represent intricate microcosms shaped by their chemical and micrometeorological properties. Notable examples include thermogenic flowers that create a warm microclimate for visitors and residents. We document a distinct microclimate within the large flowers of both wild and domesticated squashes ( Cucurbita spp .). Unlike thermogenic flowers, squash flower temperatures remain near ambient, but their humidity consistently exceeds ambient levels from bud to senescence, resulting from stomatal and petal transpiration rather than nectar evaporation. Experimentally reducing humidity in greenhouse-grown male squash flowers results in significant pollen tube rupture, directly impacting plant fitness. To explore the role of floral humidity within a broader ecological context, we performed similar humidity manipulations on squash farms to assess impacts on the behavior of their specialist squash bee pollinator ( Xenoglossa pruinosa ), generalist pollinators (bumblebees, honeybees), and specialist herbivores (cucurbit beetles). Experimentally reduced floral humidity lower visitation frequency by squash bees but have no effect on generalist pollinators. Manipulation of floral humidity did not influence the foraging duration of any pollinators but impacted the residence of male squash bees in wilted flowers compared with unmanipulated flowers. Finally, there was a positive correlation between the dryness of the ambient air and the abundance of squash bees and cucurbit beetles residing in the humid wilted floral chambers. In conclusion, our findings showcase squash flowers as a humid microhabitat that influences reproductive success directly by affecting pollen viability and indirectly by altering interactions with squash bees, their specialist pollinators.

Differences in reproductive strategies can have important implications for macro- and micro-evolutionary processes. We used a comparative approach through a population genetics lens to evaluate how three distinct reproductive strategies shape patterns of divergence among as well as gene flow and genetic diversity within three closely related taxa in the genus Clarkia. One taxon is a predominantly autonomous self-fertilizer and the other two taxa are predominantly outcrossing but vary in the primary pollinator they attract. In genotyping populations using genotyping-by-sequencing and comparing loci shared across taxa, our results suggest that differences in reproductive strategies in part promote evolutionary divergence among these closely related taxa. Contrary to expectations, we found that the selfing taxon had the highest levels of heterozygosity but a low rate of polymorphism. The high levels of fixed heterozygosity for a subset of loci suggests this pattern is driven by the presence of structural rearrangements in chromosomes common in other Clarkia taxa. In evaluating patterns within taxa, we found a complex interplay between reproductive strategy and geographic distribution. Differences in the mobility of primary pollinators did not translate to a difference in rates of genetic diversity and gene flow within taxa – a pattern likely due to one taxon having a patchier distribution and a less temporally and spatially reliable pollinator. Taken together, this work advances our understanding of the factors that shape gene flow and the distribution of genetic diversity within and among closely related taxa.

Zamia integrifolia L. f. (Cycadales), una cicadácea nativa amenazada en la Florida, depende de 2 especies nativas de escarabajos para la polinización: Rhopalotria slossoni (Chevrolat; Coleoptera: Belidae) y Pharaxanotha floridana (Casey; Coleoptera: Erotylidae). Ambos insectos son mutualistas de la polinización del sitio de cría, y se sabe que viven y se alimentan dentro del cono de polen (macho). Sin embargo, para que ocurra la polinización, los escarabajos también deben visitar conos de ovulación (femeninos), que se supone que no les ofrecen ningún beneficio como alimento o vivero. Probamos el potencial para el uso de conos de ovulación por parte de escarabajos polinizadores, esto mediante la realización de pruebas de alimentación y comportamiento de no elección para adultos de ambas especies de escarabajos tanto en conos de ovulación como en conos de polen de Z. integrifolia. Los escarabajos Rhopalotria slossoni mostraron una mayor sobrevivencia en los tejidos del cono ovulado a pesar de no mostrar diferencias significativas en la masa total de tejido consumido entre los sexos del cono. Por el contrario, P. floridana consumió más masa de tejido de las escamas de los conos de ovulación, pero no mostró diferencias en la sobrevivencia en las escamas de los conos de ovulación frente a las de los conos de polen. Aunque ninguna de las especies de escarabajos se encuentra en grandes cantidades en los conos de ovulación en el campo, nuestro estudio de laboratorio sugiere que ambas especies podrían beneficiarse potencialmente al alimentarse de los tejidos de los conos de ovulación, lo que cuestiona la hipótesis actual de que la polinización de Z. integrifolia se produce por engaño.