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opencc-zeroAug 2020View details →

Characterizing the nectar microbiome of the non-native tropical milkweed, Asclepias curassavica, in an urban environment

In increasingly urban landscapes, the loss of native pollen and nectar floral resources is impacting ecologically important pollinators. Increased urbanization has also brought about the rise of urban gardens which introduce new floral resources that may help replace those the pollinators have lost. Recently, studies have shown that the microbial communities of nectar may play an important role in plant-pollinator interactions, but these microbial communities and the floral visitors in urban environments are poorly studied. In this study we characterized the floral visitors and nectar microbial communities of Ascelpias curassavica, a non-native tropical milkweed commonly, in an urban environment. We found that the majority of the floral visitors to A. curassavica were honey bees followed closely by monarch butterflies. We also found that there were several unique visitors to each site, such as ants, wasps, solitary bees, several species of butterflies and moths, Anna's hummingbird, and the tarantula hawk wasp. Significant differences in the nectar bacterial alpha and beta diversity were found across the urban sites, although we found no significant differences among the fungal communities. We found that the differences in the bacterial communities were more likely due to the environment and floral visitors rather than physiological differences in the plants growing at the gardens. Greater understanding of the impact of urbanization on the nectar microbiome of urban floral resources and consequently their effect on plant-pollinator relationships will help to predict how these relationships will change with urbanization, and how negative impacts can be mitigated through better management of the floral composition in urban gardens.

opencc-zeroDec 2017View details →

Data from: Elevated atmospheric concentrations of carbon dioxide reduce monarch tolerance and increase parasite virulence by altering the medicinal properties of milkweeds

Hosts combat their parasites using mechanisms of resistance and tolerance, which together determine parasite virulence. Environmental factors, including diet, mediate the impact of parasites on hosts, with diet providing nutritional and medicinal properties. Here, we present the first evidence that ongoing environmental change decreases host tolerance and increases parasite virulence through a loss of dietary medicinal quality. Monarch butterflies use dietary toxins (cardenolides) to reduce the deleterious impacts of a protozoan parasite. We fed monarch larvae foliage from four milkweed species grown under either elevated or ambient CO2, and measured changes in resistance, tolerance, and virulence. The most high-cardenolide milkweed species lost its medicinal properties under elevated CO2; monarch tolerance to infection decreased, and parasite virulence increased. Declines in medicinal quality were associated with declines in foliar concentrations of lipophilic cardenolides. Our results emphasize that global environmental change may influence parasite-host interactions through changes in the medicinal properties of plants.

opencc-zeroOct 2023View details →

Of Mojave milkweed and mirrors: The population genomic structure of a species impacted by solar energy development

A rapid renewable energy transition has facilitated the development of large, ground‐mounted solar energy facilities worldwide. Deserts, and other sensitive aridland ecosystems, are the second most common land‐cover type for solar energy development globally. Thus, it is necessary to understand existing diversity within environmentally sensitive desert plant populations to understand spatiotemporal effects of solar energy siting and design. Overall, few population genomic studies of desert plants exist, and much of their biology is unknown. To help fill this knowledge gap, we sampled Mojave milkweed (Asclepias nyctaginifolia) in and around the Ivanpah Solar Electric Generating Station (ISEGS) in the Mojave Desert of California to understand the species' population structure, standing genetic variation, and how that intersects with solar development. We performed Restriction‐site Associated Sequencing (RADseq) and discovered 9942 single nucleotide polymorphisms (SNPs). Using these data, we found clear population structure over small spatial scales, suggesting each site sampled comprised a genetically distinct population of Mojave milkweed. While mowing, in lieu of blading, the vegetation across the solar energy facility's footprint prevented the immediate loss of the ISEGS Mojave milkweed population, we show that the effects of land‐cover change, especially those impacting desert washes, may impact long‐term genetic diversity and persistence. Potential implications of this include a risk of overall loss of genetic diversity, or even hastened extirpation. These findings highlight the need to consider the genetic diversity of impacted species when predicting the impact and necessary conservation measures of large‐scale land‐cover changes on species with small population sizes.

Figure 19. Feeding Phidippus from southern Greenville County, South Carolina. 1, Penultimate female P in Learned avoidance of the Large Milkweed Bug (Hemiptera: Lygaeidae: Oncopeltus fasciatus) by jumping spiders (Araneae: Salticidae: Dendryphantina: Phidippus)

Figure 19. Feeding Phidippus from southern Greenville County, South Carolina. 1, Penultimate female P. audax with two leafhoppers. This spider held one leafhopper as it jumped and captured the second. 2, Adult female P. audax fedding on a large brachyceran fly. 3, Adult female P. princeps feeding on spider. 4, Adult female P. princeps feeding on a captured bug after wiping it against the surface. Each scale bar = 1.0 mm.

Figure 20 in Learned avoidance of the Large Milkweed Bug (Hemiptera: Lygaeidae: Oncopeltus fasciatus) by jumping spiders (Araneae: Salticidae: Dendryphantina: Phidippus)

Figure 20. SEM of chemosensory setae (spondylae) associated with the pretarsus or foot of an adult male Phidippus audax from Iowa City, Iowa. 1-3, Ventral views of the distal end of right leg I at three levels of magnification. 2, A group of spondylae (inset) originates between the anterior and posterior plates of flattened tenent setae. 3, Detail showing the conical tip (arrows) at the end of three spondylae. These are surrounded by flattened tenent setae bearing, ventrally, regular rows of bifid filaments that adhere to a smooth surface. Each spondyla bears an open sensory pore at the apex of the cone.

Figure 4 in Learned avoidance of the Large Milkweed Bug (Hemiptera: Lygaeidae: Oncopeltus fasciatus) by jumping spiders (Araneae: Salticidae: Dendryphantina: Phidippus)

Figure 4. Two female Phidippus texanus (sisters) reared from the same brood sac found in Lea County, New Mexico, in August of 1978 (on mesquite 21 miles W of Jal on SR 128). Half of the females in this brood had the typical texanus form with cream to white scales on a black background (1), and the other half had a similar dorsal pattern with the coloration of the related P. ardens, with rust-red scales covering much of the dorsal opisthosoma. Edwards (2004) placed P. ardens and P. texanus in the borealis clade of the purpuratus group within Phidippus, but kept the species separate in part because of their parapatric ranges. However, he did report both species from Lea County, New Mexico where this brood sac was found, and both live on mesquite. These are very large Phidippus, with females averaging 13-15 mm in body length.

Figure 3 in Learned avoidance of the Large Milkweed Bug (Hemiptera: Lygaeidae: Oncopeltus fasciatus) by jumping spiders (Araneae: Salticidae: Dendryphantina: Phidippus)

Figure 3. Two views of an adult female Phidippus princeps captured in an old field in Ithaca, Tompkins County, New York (1978). In this area female P. princeps were tan in color, often with abundant white or cream-colored facial scales as shown here. At least as juveniles, they build their nests and hunt on herbaceous plants in old field habitats. They are common in eastern North America, from Minnesota southeast to northwestern South Carolina and northern Georgia. Further to the southeast, they are replaced by the closely related P. pulcherrimus Keyserling 1885, also an inhabitant of old fields (Edwards 2004). Note the distinctive 'hair' tufts on the carapace, a characteristic of most Phidippus jumping spiders.

Figure 2 in Learned avoidance of the Large Milkweed Bug (Hemiptera: Lygaeidae: Oncopeltus fasciatus) by jumping spiders (Araneae: Salticidae: Dendryphantina: Phidippus)

Figure 2. Two adult female Phidippus audax captured in an old field in Ithaca, Tompkins County, New York (1978). Many local varieties of P. audax do not have the broad lateral band of opisthosomal scales shown here. P. audax appears to be a generalist with respect to habitat and it is widely distributed across much of North America, with many recent sightings in the far west. It can frequently be found living on herbaceous plants in old fields, but I have also found it near water, woodland margins, on trees, on fence posts, and even nesting on the ground under rocks.

Figure 18 in Learned avoidance of the Large Milkweed Bug (Hemiptera: Lygaeidae: Oncopeltus fasciatus) by jumping spiders (Araneae: Salticidae: Dendryphantina: Phidippus)

Figure 18. Oncopeltus fasciatus aggregating on Asclepias leaves and seed pods in southern Greenville County, South Carolina. These insects pierce seed pods to feed on seeds. 1, Pair of immatures resting on top of an Asclepias leaf. 2, Two adults feeding on seed pod. 3, Aggregation of mating adult pairs. 4, Lateral view of adult showing long stylus. 5, Dorsal view of adult.

Figure 14 in Learned avoidance of the Large Milkweed Bug (Hemiptera: Lygaeidae: Oncopeltus fasciatus) by jumping spiders (Araneae: Salticidae: Dendryphantina: Phidippus)

Figure 14. Recovery of tendency to attack by adult female Phidippus audax. Each spider was placed in a clean Petri dish with one adult Oncopeltus reared on Asclepias reared. After an initial attack (t=0), the behavior of 40 spiders (numbered at left) was charted through either the third sequential attack, or until 15 minutes had elapsed, whatever came first. Turns to face the bugs are shown as green circles, and attacks (jump and contact) are shown as red circles.

Figure 6 in Learned avoidance of the Large Milkweed Bug (Hemiptera: Lygaeidae: Oncopeltus fasciatus) by jumping spiders (Araneae: Salticidae: Dendryphantina: Phidippus)

Figure 6. Violent reaction of an adult female Phidippus princeps to fluids associated with an adult Oncopeltus fasciatus. 1, This spider first bit the bug on its head but held its legs and pedipalps far away from the prey. 2, Moments later, the spider dropped the fatally-bitten bug, and began to wipe its mouthparts against the surface, leaving a trail of fluid behind (fluid cannot be seen in these photographs).

opencc-zeroOct 2022View details →

Data from: Distinct developmental mechanisms influence sexual dimorphisms in the milkweed bug Oncopeltus fasciatus

Sexual dimorphism is common in animals. The most complete model of sex determination comes from Drosophila melanogaster, where the relative dosage of autosomes and X chromosomes leads indirectly to sex-specific transcripts of doublesex (dsx). Female Dsx interacts with a mediator complex protein encoded by intersex to activate female development. In males the transcription factor encoded by fruitless promotes male-specific behavior. The genetics of sex determination have been examined in a small number of other insects, yet several questions remain about the plesiomorphic state. Is doublesex required for female and male development? Is fruitless conserved in male behavior or morphology? Are other components such as intersex functionally conserved? To address these questions, we report the expression and functional tests of doublesex, intersex and fruitless in the hemipteran Oncopeltus fasciatus, characterizing three sexual dimorphisms. doublesex prevents intersex phenotypes in all sexes and dimorphic traits in the milkweed bug. intersex and fruitless are expressed across the body, in females and males. fruitless and intersex also affect the genitalia of both sexes but have effects limited to different dimorphic structures in different sexes. These results reveal roles for intersex and fruitless distinct from other insects and demonstrate distinct development mechanisms in different sexually dimorphic structures.

opencc-zeroMay 2024View details →

Identifying priority survey sites for early-season milkweed conservation

Monarch butterfly (Danaus plexippus) populations are experiencing decline due to habitat degradation and climate threats. In 2024, this iconic species became protected under the Endangered Species Act. Critical to the persistence of this species of cultural and ecological importance is milkweed (Asclepias spp.), which monarchs rely on as an essential resource for food and reproduction. Motivated by concerns over the loss of monarch habitat, the Santa Barbara Botanic Garden (SBBG) and local collaborators are working to identify potential restoration areas in the Los Padres National Forest (LPNF). However, the vast size and complex terrain of the LPNF pose a logistical challenge to surveying. Therefore, there is a need for a tool to aid in selecting sites to prioritize. Our team created a priority index for surveying milkweed within the LPNF by predicting the habitat suitability for four early-season milkweed species using Maximum Entropy (MaxEnt) species distribution modeling and creating a novel survey site accessibility index. We identified high priority sites for the team to survey based on high predicted suitability for each species of early-season milkweed and high physical accessibility. To communicate these results, we created an interactive web dashboard, which the SBBG team will use for field planning to support the ongoing monitoring of milkweed populations for monarch habitat restoration efforts within the LPNF.

opencc-by-4.0Dec 2016View details →

Fig. 4 in Aposematism and unpalatability in the Chilean milkweed bug Oncopeltus (Erythrischius) miles (Blanchard, 1852) (Heteroptera: Lygaeidae): experiences with spiders (Arachnida: Araneae).

Fig. 4.- Oncopeltus miles recently emerged nymphs with Frigga crocuta adult and its ootheca.