Host Plant Phenology Research Articles

The temporal distribution of endophytic and exophytic insect guilds responds to host plant phenology in the Brazilian Savannah

Abstract Niche theory predicts high specialisation in species‐rich environments such as neotropics, where plant‐herbivore interactions are ubiquitous in all terrestrial systems. However, there is much to be explored on how different insect guilds respond to plant phenology in these specialised environments. Using a Fabaceae‐herbivore community as an ecological model, we evaluated how plant phenology affects the abundance and shapes the temporal distribution of exophytic (folivore chewers) and endophytic (seed chewers) insects. We tested the specialisation hypothesis, predicting insect species on only one or a few host plants, with a seasonal pattern of occurrence, many rare and few abundant species. Additionally, we analysed the relationship between plant phenology and environmental factors (temperature and precipitation). We conducted fieldwork with five species and 97 individuals of Fabaceae in Brazilian Savannah and performed an insect‐rearing study in the laboratory. We found an immediately synchronised relationship between endophytic insects and plant phenology in the dry season, whereas exophytic were throughout the year. Only six species from the exophytic guild, out of a total of 87 species for both guilds, fed on more than one host plant, showing a specialised network. Endophytic herbivores are more abundant, ephemeral and predictable than exophytic ones. We also found a negative relationship between fruiting and precipitation and a positive relationship between new leaves and temperature and precipitation. Our study shows that the temporal distribution of insect‐herbivore guilds responds to plant phenology. In a scenario of global warming with effects on the annual precipitation, endophytic insects are most vulnerable to local extinction due to temporal changes in plant phenology than the exophytic ones.

Phenological alignment of a galling insect used as biocontrol agent for an invasive tree following hemisphere translocation

Acacia longifolia is one of the most widespread invasive alien plant species along coastal areas in Portugal. In South Africa, this species is also invasive and has been controlled for over 40 years by the Australian gall wasp Trichilogaster acaciaelongifoliae. This biological control agent was introduced in Portugal in 2015, being released immediately after import, i.e., without a laboratory rearing period to adjust the life cycle, and is now established in many locations along the coast. When released in the northern hemisphere, the agent came from the austral spring, with the host-plants having tiny buds, and faced boreal winter with host-plants having large buds. As such it had to synchronize its life cycle with the seasons and phenology of the host-plant in this new location. Both locations have mild summer Mediterranean climates. The present work aims to better understand the life cycle of T. acaciaelongifoliae in the northern hemisphere and how it has aligned its phenology to these new conditions, namely different host-plant phenology and seasons. Two sites were selected (Pataias and São Jacinto), and monitored monthly, from November 2021 to October 2022, to: i) describe the early stages of the life cycle, since oviposition, by collecting and dissecting A. longifolia buds of 5 branches/five trees/site; ii) characterize the stages of the life cycle of T. acaciaelongifoliae inside the developing galls, by collecting and analysing 50 galls/site; and iii) monitoring the development of galls on 10 A. longifolia marked branches/ five trees, in the field. The results suggest that T. acaciaelongifoliae in the northern hemisphere has a univoltine life cycle, but the generations are not completely synchronized at the two sites and even within each site. It is not excluded that two generations may occur throughout the year, i.e., a bivoltine cycle, in some individuals. The alignment of the life cycle may not yet be stabilized. The life cycle seems to be more advanced in the site located further south, Pataias, where adults emerged earlier. Reproductive galls dominated in almost all months, as in South Africa. The present work advances the knowledge on the life cycle of T. acaciaelongifoliae, especially in the northern hemisphere, providing details about the timings and duration of each life cycle stage in this new location. These results are relevant for the management of A. longifolia, stressing the plasticity of the agent life cycle which can facilitate the planning of the biocontrol agent releases in new locations.

Interspecific interaction network of mites associated with mango trees.

Direct and indirect ecological interactions, environmental factors, and the phenology of host plants can shape the way mites interact. These relationships interfere with species occurrence and consequently alter the structure and stability of the intraplant community. As predatory mites act as regulators of herbivorous mites, we hypothesized that these mites may occupy a central position in a network of interactions among mite species associated with mango trees, and the occurrence of these species is mediated by environmental variables and the phenological stage of the host plant. We evaluated the global structure of the interaction network of mites associated with individual Mangifera indica plants and analyzed the interspecific relationships of the species using an undirected Bayesian network approach. Additionally, we observed a correlation between mite population density and plant phenological stage. Environmental variables, such as average monthly temperature, monthly precipitation, and average monthly relative humidity at different sampling date were used in the correlation analysis. The modularity at the mite-plant network level showed a low specialization index H2 = 0.073 (generalist) and high robustness (R = 0.93). Network analysis revealed that Amblyseius largoensis, Bdella ueckermanni, Parapronematus acaciae, and Tuckerella ornata occupied central positions in the assembly of mites occurring on mango trees. Environmental variables, average monthly temperature, and monthly precipitation were correlated with the occurrence of Brachytydeus formosa, Cisaberoptus kenyae, Oligonychus punicae, T. ornata, and Vilaia pamithus. We also observed a correlation between the plant phenological stage and population densities of Neoseiulus houstoni, O. punicae, P. acaciae, and V. pamithus.

Host-plant phenology mediates facultative ant mutualism in the rare butterfly, Celastrina humulus (Lepidoptera: Lycaenidae).

Host-plant phenology can directly and indirectly mediate the abundance of insect herbivores. Our objective was to determine how host-plant flowering phenology shapes a facultative ant-lycaenid mutualism. The focus of our research was the hops azure, Celastrina humulus Scott & D. Wright, a rare species whose larvae feed on the pollen-bearing inflorescences of Humulus lupulus var. neomexicanus. We used several approaches to evaluate the role of host-plant flowering phenology in this system. First, we monitored larvae over three study years (2020-2022) to parse the role of host-plant flowering phenology and other factors in shaping the likelihood of ant tending. Second, we tested larval performance at various phenological stages of the host plant. We also quantified variation in soluble proteins and secondary metabolites among inflorescences at varying phenological stages. Lastly, we treated artificial sugar-protein baits with extracts from different phenological stages of the host plant; this allowed us to assess how chemical variation among stages could impact ant recruitment. Monitoring results revealed that the likelihood of ant tending was lowest for larvae on host plants with early-stage inflorescences. These floral stages had the greatest concentrations of both soluble proteins and α-acids (humulone and cohumulone), and in the feeding trial, early-stage flowers enabled greater weight gain for larvae. However, extracts from early-stage flowers reduced ant recruitment to sugar-protein baits. Altogether, these results suggest that early-stage inflorescences enhance larval growth while also reducing the recruitment of mutualist ants. This shows an indirect mechanism whereby changing host-plant phenology can mediate herbivore populations through interactions with ants.

Changes in the Carpathian fauna of Malachiinae beetles (Coleoptera, Melyridae) in the context of temperature increase

Over last century in Europe a tendency of change in species ranges has occurred for insects of different taxonomic groups. We analyzed the changes that have taken place in the distribution of some soft-winged beetles (Malachiinae, Melyridae) species in the Carpathian region. The obtained data are based on a study of museum beetles’ collections and the authors’ collected materials. Data comparison relating to species distribution shows that the Carpathian fauna during the second half of the 20th century increased by 12 species. Some species have significantly changed their ranges. Species of Southern European and Mediterranean (Anthomalachius strangulatus, Clanoptilus spinipennis), Central-East European (Apalochrus femoralis, Clanoptilus falcifer) origin spread to the East Carpathian region. And vice versa, some species (e.g. Malachius scutellaris) from Central European and the Carpathian regions have spread beyond their borders of ranges to the East and North. Malachiinae species are anthophilic insects. Their life cycles, flight period, and distribution depend on the phenology of host plants. Acceleration of phenophases of the host plants and intensification of the metamorphosis processes due to increase in air temperature has caused an earlier appearance of soft-winged beetles in recent years and contributed to expansion of the ranges of some species of them. In our opinion, expansion of the species ranges and penetration of new beetle species into the Carpathian region from surrounding areas are related to the climate changes, in particular to warming. This thesis is confirmed by multiyear air temperature data of the Transcarpathian Centre of Hydrometeorology. On a background of increase in regional air temperature by about 0.8 °C an average air temperature in foothills of Ukrainian Carpathians has increased by 1.7 °C during last 50–60 years.

Season and herbivore defence trait mediate tri-trophic interactions in tropical rainforest.

Bottom-up effects from host plants and top-down effects from predators on herbivore abundance and distribution vary with physical environment, plant chemistry, predator and herbivore trait and diversity. Tri-trophic interactions in tropical ecosystems may follow different patterns from temperate ecosystems due to differences in above abiotic and biotic conditions. We sampled leaf-chewing larvae of Lepidoptera (caterpillars) from a dominant host tree species in a seasonal rainforest in Southwest China. We reared out parasitoids and grouped herbivores based on their diet preferences, feeding habits and defence mechanisms. We compared caterpillar abundance with leaf numbers ('bottom-up' effects) and parasitoid abundance ('top-down' effects) between different seasons and herbivore traits. We found bottom-up effects were stronger than top-down effects. Both bottom-up and top-down effects were stronger in the dry season than in the wet season, which were driven by polyphagous rare species and host plant phenology. Contrary to our predictions, herbivore traits did not influence differences in the bottom-up or top-down effects except for stronger top-down effects for shelter-builders. Our study shows season is the main predictor of the bottom-up and top-down effects in the tropics and highlights the complexity of these interactions.

Intrapopulation variance in ecophysiological responses to water limitation in a butterfly metapopulation suggests adaptive resilience to environmental variability.

How organisms that are part of the same trophic network respond to environmental variability over small spatial scales has been studied in a multitude of systems. Prevailing theory suggests a large role for plasticity in key traits among interacting species that allows matching of life cycles or life-history traits across environmental gradients, for instance insects tracking host-plant phenology across variable environments (Posledovich et al.2018). A key aspect that remains understudied is the extent of intrapopulation variability in plasticity and whether stressful conditions canalize plasticity to an optimal level, or alternatively if variation in plasticity indeed could increase fitness in itself via alternative strategies. In a From the Cover article in this issue of Molecular Ecology, Kahilainen et al. (2022) investigate this issue in a classical insect study system, the metapopulation of the Glanville fritillary butterfly (Melitea cinxia) in the Åland archipelago of Finland. The authors first establish how a key host plant responds to water limitation, then quantify among-family variation in larval growth and development across control and water-limited host plants. Finally, they use RNA sequencing to gain mechanistic insights into some of these among-family differences in larval performance in response to host-plant variation, finding results suggesting the existence of heritable, intrapopulation variability in ecologically relevant plasticity. This final step represents a critically important and often overlooked component of efforts to predict sensitivity of biological systems to changing environmental conditions, since it provides a key metric of adaptive resilience present in the system.

Host plant phenology shapes aphid abundance and interactions with ants

Phenological mismatch can occur when plants and herbivores differentially respond to changing phenological cues, such as temperature or snow melt date. This often shifts herbivore feeding to plant stages of lower quality. How herbivores respond to plant quality may be also mediated by temperature, which could lead to temperature‐by‐phenology interactions. We examined how aphid abundance and mutualism with ants were impacted by temperature and host plant phenology. In this study system, aphids Aphis asclepiadis colonize flowering stalks of the host plant, Ligusticum porteri. Like other aphids, abundance of this species is dependent on ant protection. To understand how host plant phenology and temperature affect aphid abundance, we used a multiyear observational study and a field experiment. We observed 20 host plant populations over five years (2017–2021), tracking temperature and snow melt date as well as host plant phenology and insect abundance. We found host plant and aphid phenology to differentially respond to temperature and snow melt timing. Early snow melt accelerated host plant phenology to a greater extent than aphid phenology, which was more responsive to temperature. Both the likelihood of aphid colony establishment and ant recruitment were reduced when aphids colonized host plants at post‐flowering stages. In 2019, we experimentally accelerated host plant phenology by advancing snow melt date by two weeks. We factorially combined this treatment with open top warming chambers surrounding aphid colonies. Greatest growth occurred for colonies under ambient temperatures when they occurred on host plants at the flowering stage. Altogether, our results suggest that phenological mismatch with host plants can decrease aphid abundance, and this effect is exacerbated by temperature increases and changes to the ant–aphid mutualism.

Mapping the Spatio-Temporal Distribution of Fall Armyworm in China by Coupling Multi-Factors

The fall armyworm (FAW) (Spodoptera frugiperda) (J. E. Smith) is a migratory pest that lacks diapause and has raised widespread concern in recent years due to its global dispersal and infestation. Seasonal environmental changes lead to its large-scale seasonal activities, and quantitative simulations of its dispersal patterns and spatiotemporal distribution facilitate integrated pest management. Based on remote sensing data and meteorological assimilation products, we constructed a mechanistic model of the dynamic distribution of FAW (FAW-DDM) by integrating weather-driven flight of FAW with host plant phenology and environmental suitability. The potential distribution of FAW in China from February to August 2020 was simulated. The results showed a significant linear relationship between the dates of the first simulated invasion and the first observed invasion of FAW in 125 cities (R2 = 0.623; p < 0.001). From February to April, FAW was distributed in the Southwestern and Southern Mountain maize regions mainly due to environmental influences. From May to June, FAW spread rapidly, and reached the Huanghuaihai and North China maize regions between June to August. Our results can help in developing pest prevention and control strategies with data on specific times and locations, reducing the impact of FAW on food security.

Development, Survival and Reproduction of Spodoptera frugiperda (Lepidoptera: Noctuidae) Fed an Artificial Diet or on Cotton, Castor Bean and Corn Leaves.

Simple SummaryThe fall armyworm (Lepidoptera: Noctuidae) is one of the main pests of corn and cotton in South American countries, but it can also feed and survive on castor bean. These plants are cultivated in Brazil in an intercropping and/or succession system in small and large rural properties, at different times of the year near to each other, what can facilitate the movement of this pest and make it difficult to control. The results obtained are promising and confirm our hypothesis that the consumption of host crops less suitable for the fall armyworm can impair its development, survival and reproduction, reducing its infestation in the next host.The polyphagy of Spodoptera frugiperda (Lepidoptera: Noctuidae) renders its control difficult because variations in the phenology of host plants grown in different seasons of the year and near each other can facilitate the movement of this pest between crops. The objective of this work was to examine certain biological characteristics of S. frugiperda fed on an artificial diet or on cotton, castor bean, or corn leaves. The experimental design was in randomized blocks, with four treatments represented by S. frugiperda caterpillars fed an artificial diet (T1) or pieces of cotton (T2), castor bean (T3) or corn (T4) leaves with five replications (five caterpillars per replication). The duration and survival of the egg, larva, pre-pupa, pupa and egg-adult period and the reproductive characteristics of this insect were determined. The survival, development and reproduction data of S. frugiperda originated from individuals reared with cotton and castor bean leaves were lower than those fed on corn leaves or an artificial diet. The number of nonviable eggs laid by females originated from caterpillars fed on castor bean leaves was higher than those fed on cotton and corn leaves or an artificial diet. The very higher number of unviable S. frugiperda eggs resulting from castor leaves can reduce outbreaks of this pest in cotton and corn crops after the cultivation of that plant, or by intercropping with this plant, in the main producing regions of Brazil.

Seasonal Variation in Host Plant Chemistry Drives Sequestration in a Specialist Caterpillar

Sequestration of plant secondary metabolites by herbivores can vary across both host plant phenology and herbivore ontogeny, but few studies have explored how they concurrently change in the field. We explored variation in iridoid glycoside concentration and composition in white turtlehead, Chelone glabra, as well as sequestration of iridoid glycosides by its specialist herbivore, the Baltimore checkerspot, Euphydryas phaeton, across the development of both herbivore and host plant. In 2012 we sampled plants to describe seasonal variation in the concentrations of two iridoid glycosides, aucubin and catalpol. In 2017, we sampled both host plants and caterpillars over an entire growing season and explored the relationship between plant chemistry and herbivore sequestration. We also compared iridoid glycoside concentrations of plants with and without herbivory to gain insight into whether levels of secondary compounds were impacted by herbivory. We found that total plant iridoid glycosides varied across the season and that total sequestered iridoid glycosides in caterpillars closely mirrored concentration patterns in plants. However, the magnitude of sequestration by caterpillars ranged from 2 to 20 times the concentrations in host plants, with different proportions of aucubin and catalpol. In addition, plants with herbivory had lower iridoid glycoside concentrations than plants without herbivory, although this difference changed over time. These results suggest that while variation in host plant secondary metabolites may be a dominant factor driving sequestration, other ecological factors may mitigate the relationship between host plant chemistry and herbivore sequestration.

An Integrative Study on Asphondylia spp. (Diptera: Cecidomyiidae), Causing Flower Galls on Lamiaceae, with Description, Phenology, and Associated Fungi of Two New Species

Simple SummaryCurrent knowledge of some species of Asphondylia (Diptera: Cecidomyiidae) is very scarce, such as those causing flower galls on Lamiaceae. Their role in natural and agricultural ecosystems remains to be investigated. Hitherto, the description of new species of this genus was mostly based on morphological variations of both the adult and the young instars. However, these variations are frequently limited and unreliable for species discrimination, and need the essential support of molecular data. Interesting aspects that are widely unexplored of this group of Asphondylia are their biological traits and the association with parasitoids and fungi. This paper provides an integrated description of two species of Asphondylia infesting flowers of Clinopodium vulgare and Micromeria graeca, and also provides data on host range and symbiosis with associated fungi.An integrative study on some species of Asphondylia was carried out. Two species of gall midges from Italy, Asphondylia rivelloi sp. nov. and Asphondylia micromeriae sp. nov. (Diptera: Cecidomyiidae), causing flower galls respectively on Clinopodium vulgare and Micromeria graeca (Lamiaceae), are described and illustrated. The characteristics of each developmental stage and induced galls are described, which allowed the discrimination of these new species in the complex of Asphondylia developing on Lamiaceae plants. Molecular data based on sequencing both nuclear (ITS2 and 28S-D2) and mitochondrial (COI) genes are also provided in support of this discrimination. Phylogeny based on nuclear markers is consistent with the new species, whereas COI phylogeny suggests introgression occurring between the two species. However, these species can also be easily identified using a morphological approach. Phenology of host plants and gall midges are described, and some peculiar characteristics allow the complete and confident discrimination and revision of the treated species. Gall-associated fungi were identified as Botryosphaeria dothidea, Alternaria spp., and Cladosporium spp.

Staying in touch: how highly specialised moth pollinators track host plant phenology in unpredictable climates

BackgroundFor specialised pollinators, the synchrony of plant and pollinator life history is critical to the persistence of pollinator populations. This is even more critical in nursery pollination, where pollinators are obligately dependant on female host plant flowers for oviposition sites. Epicephala moths (Gracillariidae) form highly specialised nursery pollination mutualisms with Phyllanthaceae plants. Several hundred Phyllanthaceae are estimated to be exclusively pollinated by highly specific Epicephala moths, making these mutualisms an outstanding example of plant–insect coevolution. However, there have been no studies of how Epicephala moths synchronise their activity with host plant flowering or persist through periods when flowers are absent. Such knowledge is critical to understanding the ecology and evolutionary stability of these mutualisms. We surveyed multiple populations of both Breynia oblongifolia (Phyllanthaceae) and it’s Epicephala pollinators for over two years to determine their phenology and modelled the environmental factors that underpin their interactions.ResultsThe abundance of flowers and fruits was highly variable and strongly linked to local rainfall and photoperiod. Unlike male flowers and fruits, female flowers were present throughout the entire year, including winter. Fruit abundance was a significant predictor of adult Epicephala activity, suggesting that eggs or early instar larvae diapause within dormant female flowers and emerge as fruits mature. Searches of overwintering female flowers confirmed that many contained pollen and diapausing pollinators. We also observed diapause in Epicephala prior to pupation, finding that 12% (9/78) of larvae emerging from fruits in the autumn entered an extended diapause for 38–48 weeks. The remaining autumn emerging larvae pupated directly without diapause, suggesting a possible bet-hedging strategy.ConclusionsEpicephala appear to use diapause at multiple stages in their lifecycle to survive variable host plant phenology. Furthermore, moth abundance was predicted by the same environmental variables as male flowers, suggesting that moths track flowering through temperature. These adaptations may thereby mitigate against unpredictability in the timing of fruiting and flowering because of variable rainfall. It remains to be seen how widespread egg diapause and pre-pupal diapause may be within Epicephala moths, and, furthermore, to what degree these traits may have facilitated the evolution of these highly diverse mutualisms.

The specialist of a specialist: the natural history of the predispersal seed predator weevil Hemicolpus abdominalis (Coleoptera: Curculionidae)

1. The reproduction of specialised endophagous insects relies on a fine temporal synchronization between the insect and its host plant phenology.2. Since the spatial distribution and local prevalence of specialised insects depend on both environmental conditions and biotic interactions, in this study, we assessed whether the life cycle of the predispersal seed feeding weevil, Hemicolpus abdominalis (Curculionidae), is synchronised with the reproductive phenology of its host plant, Tocoyena formosa (Rubiaceae) in the Brazilian Cerrado. Following an ecological niche modelling approach, we also tested whether the predicted distribution of this specialised weevil matches that of its host plant.3. We observed a tight synchronization between the weevil reproduction and its host plant reproductive phenology. After emergence from the fruits, adult weevils enter in reproductive diapause, with reproductive development resuming in the next reproductive season, which indicates the univoltism of this species.4. There was a high spatial congruence in the distribution of H. abdominalis and its host plant. Since the reproduction of H. abdominalis is synchronised with the host plant phenology, temporal mismatches between the weevil life cycle, and plant reproduction may affect the long‐term population prevalence of the insect.5. The life cycle of the predispersal seed feeding weevil, H. abdominalis, depends on a close match with the host plant reproductive phenology, whose fruit production is entirely dependent on long‐tongued hawkmoth pollinators. Hence, we highlight the importance of both biotic and abiotic conditions in shaping the distribution range of a specialised endophagous insect.

Genotype-environment interaction reveals varied developmental responses to unpredictable host phenology in a tropical insect.

Understanding the genetic architecture of life history plasticity may inform resilience under environmental change, but relatively little is known for the inhabitants of unpredictable wet-dry tropical environments. Here, I explore the quantitative genetics of juvenile growth and development relative to hostplant phenology in the butterfly Eurema hecabe. Wet season generations of this species breed explosively on leguminous annuals whereas dry season generations subsist at low density upon an alternative perennial host. The wet-to-dry season transition is temporally unpredictable and marked by widespread host defoliation, forcing a large cohort of stranded larvae to either pupate prematurely or prolong development in the hope of renewed foliage production. A split-brood experiment demonstrated greater performance on high quality annual as opposed to perennial host foliage and a marked decline under the stressed conditions faced by stranded wet season larvae. Genetic variances for rates of growth and development were equivalent among high quality treatments but strikingly elevated under resource stress, and the associated cross-environment genetic correlations were indistinguishable from zero. The results demonstrate genotype-environment interaction involving both rank order and variance scale, thereby revealing genetic variance for norms of reaction that may reflect variable risk aversion given an unpredictable tropical host phenology.

Early snowmelt reduces aphid abundance (Aphis asclepiadis) by creating water-stressed host plants (Ligusticum porteri) and altering interactions with ants

Declining snow cover is reshaping ecological communities. Early loss of snow cover initiates changes in key interactions that mediate herbivore abundance, i.e., top-down and bottom-up effects. In this study, we used a field experiment to test the effects of host plant water stress and phenology on the multitrophic interactions that determine aphid abundance. The aphid, Aphis asclepiadis, in our study system colonizes the flowering stalks of the host plant Ligusticum porteri and relies on a protection mutualism with ants. We added snow and water to replicate host plants and tested for a variety of phenological and physiological responses to these treatments. Relative to host plants in ambient conditions, both water and snow addition reduced key signals of water stress (senescence and abscisic acid levels) and increased seed set. While aphid colonies were generally larger with reduced host plant water stress, the ant–aphid mutualism interacted with plant quality in complex ways. Without ant tending, we did not detect differences in aphid colony growth with host plant treatment. When tended by ants, aphid colony growth was greatest on host plants with snow addition. Host plant quality also altered the benefits exchanged in this mutualism. Ant-tended colonies hosted by plants with snow addition produced honeydew enriched in trehalose, which may have decreased both ant and natural enemy abundance. Our results suggest that early loss of snow reduces aphid abundance by creating low-quality, water-stressed host plants, and this effect may be exacerbated by natural enemies and the costs of ant attendance.

Snowmelt timing determines aphid abundance through multitrophic interactions

Ecologically important relationships are being altered by climate change. It is important to understand these relationships in order to predict future changes in species distribution and abundance. Previous research has shown that aphid (Aphis asclepiadis) abundances correlate significantly with snowmelt date in subalpine Rocky Mountain ecosystems, with late snowmelt years correlating with larger aphid populations in summer. Although consistent across years, the mechanisms underlying this phenomenon have not been previously identified. We suspected early snowmelt decreases aphid abundance by inducing early season host plant drought stress. In this study, we used an elevation gradient to mimic year-to-year variation in snowmelt date. We experimentally added soil moisture to separate the effects of early season drought stress on aphid populations from other effects of elevation and snowmelt date. Our manipulations resulted in significant responses in aphid abundance, ant abundance, aphid predators, and plant quality yet revealed host plant drought stress was a minor mechanism by which snowmelt determined aphid abundance. Instead, host plant phenology and mutualist behavior appeared to greatly influence aphid abundance. This research highlights the importance of considering multi-trophic interactions in determining the effects of climate change and how changes of snowmelt dates may be affecting insect communities.

Ecology of the Western Queen Butterfly Danaus gilippus thersippus (Lepidoptera: Nymphalidae) in the Mojave and Sonoran Deserts.

The purpose of this study was to assess the ecological knowledge surrounding the western queen butterfly, Danaus gilippus thersippus (H. Bates). Specifically, our objectives were to synthesize existing data and knowledge on the ecology of the queen and use results of this assessment to inform the direction of future research on this understudied species. We identified six core areas for assessment: distribution, the biodiversity of plant resources, western queen and their host plant phenology, chemical ecology, and four key life history traits. We mapped the distribution of D. g. thersippus from museum specimen records, citizen science (e.g., iNaturalist) and image sharing app-based observations, along with other observational data enumerating all current known plant resources and long-range movements. We assembled 14 larval food plants, six pyrrolizidine alkaloids plants and six nectar plants distributed in the western Mojave and Sonoran Desert regions of the United States and Baja California. We report on its phenology and its long-range movement. Butterfly species have declined across the western US, and western monarch populations have declined by 97%. Danaus g. thersippus has received little research attention compared with its famous congener D. plexippus L. Danaus g. thersippus’ desert distribution may be at its temperature limits for the species distribution and for its rare host plant Asclepias nyctaginifolia.

Host plant phenology, insect outbreaks and herbivore communities - The importance of timing.

Climate change may alter the dynamics of outbreak species by changing the phenological synchrony between herbivores and their host plants. As host plant phenology has a genotypic component that may interact with climate, infestation levels among genotypes might change accordingly. When the outbreaking herbivore is active early in the season, its infestation levels may also leave a detectable imprint on herbivores colonizing the plant later in the season. In this study, we first investigated how the spring phenology and genotype of Quercus robur influenced the density of the spring-active, outbreaking leaf miner Acrocercops brongniardellus. We then assessed how intraspecific density affected the performance of A. brongniardellus and how oak genotype and density of A. brongniardellus affected the insect herbivore community. We found that Q. robur individuals of late spring phenology were more strongly infested by A. brongniardellus. Conspecific pupae on heavily infested oaks tended to be lighter, and fewer heterospecific insect herbivores colonized the oak later in the season. Beyond its effects through phenology, plant genotype left an imprint on herbivore species richness and on two insect herbivores. Our results suggest a chain of knock-on effects from plant phenology, through the outbreaking species to the insect herbivore community. Given the finding of how phenological synchrony between the outbreak species and its host plant influences infestation levels, a shift in synchrony may then change outbreak dynamics and cause cascading effects on the insect community.

Bracon zuleideae Perioto & Lara (Hymenoptera, Braconidae): seed predation potential, expansion of the geographic distribution and new data on host plant phenology

Abstract. Here, by the first time, was quantified the predation of seeds of Protium ovatum Engl. (Burseraceae) by Bracon zuleideae Perioto & Lara (Hymenoptera, Braconidae), a phytophagous seed eater, in Parque Nacional Grande Sertão Veredas, located in the State of Minas Gerais, Brazil. B. zuleideae is now mentioned for the state of Minas Gerais, Brazil, which extends its geographical distribution about 900 km north of its type locality, its only previous record, and new data about host plant phenology are provided.Bracon zuleideae Perioto & Lara (Hymenoptera, Braconidae): potencial de predação de sementes, expansão da distribuição geográfica e novos dados de fenologia da planta hospedeiraResumo. A predação de sementes de Protium ovatum Engl. (Burseraceae) por Bracon zuleideae Perioto & Lara (Hymenoptera, Braconidae) foi quantificada pela primeira vez no Parque Nacional Grande Sertão Veredas, em Minas Gerais, Brasil. A distribuição geográfica de B. zuleideae é estendida para o Estado de Minas Gerais, Brasil, a cerca de 900 km ao norte da localidade tipo, o único registro anterior, e novos dados sobre a fenologia da planta hospedeira são fornecidos.