Search

Insects play a fundamental role in ecosystem stability by providing important ecological services such as pollination, biological pest control, and nutrition for other organisms. Recent human-caused declines in insect populations mandate that we better understand how to improve and sustain insect diversity and abundance. The goal of our study was to identify the insects associated with 6 prairie plant species. We spent 248 hours over 3 months during 1 year monitoring insect visits to 10 replicates of ∼1-m2 patches each of Verbena brasiliensis (Brazilian Vervain, Verbenaceae), Pycnanthemum muticum (Blunt Mountainmint, Lamiaceae), Monarda fistulosa (Wild Bergamot, Lamiaceae), Eryngium yuccifolium (Rattlesnake Master, Apiaceae), Silphium gracile (Slender Rosinweed, Asteraceae), and Rudbeckia texana (Texas Coneflower, Asteraceae). We identified 11 bee species and 100 non-bee species representing 9 orders and 57 families. Insect richness varied widely among plant species: More taxa (n = 75) visited Blunt Mountainmint than any other plant species. Wild Bergamot had the fewest visiting taxa (n = 23). The majority of insects visited multiple plants, although we observed 2 bee species and 44 non-bee species on only 1 plant species. The number of unique insect visitors of each plant species varied from 1 to 19 taxa. Total insect richness was significantly greater in the morning than afternoon (χ2 = 3.7, P = 0.054). That plant diversity begets insect diversity is widely accepted, and our work suggests that inclusion of plants that are strong insect attractors could be integral to insect conservation and restoration initiatives.

Herein we provide direct evidence for the consumption of Pomacea maculata (Giant Applesnail) eggs by ants in the genus Crematogaster. The observations were made during removal of snail egg masses at the Hudson Woods Unit of the Texas Mid-Coast National Wildlife Refuge, TX. We observed acrobat ants (Crematogaster sp.) removing snail eggs from an egg mass and carrying eggs back to their nest. While predation on Pomacea applesnail eggs has been reported elsewhere, to our knowledge this is the first time that it has been observed in North America.

The charismatic bee-mimic robber fly Mallophora fautrix (Bee Killer) is distributed throughout the southwestern US and Mexico. Recent sightings of M. fautrix in Louisiana represent the easternmost reports of the species. We photographed and identified M. fautrix in north Lafayette Parish, LA, on 5 August 2015. This 2015 discovery and a second sighting in Bossier City, LA, on 28 July 2019, extend the eastern range of this charismatic bee-mimic robber fly.

Worldwide, trees are confronting increased temperature and aridity, exacerbating susceptibility to herbivory. Long-term studies comparing patterns of plant performance through drought can help identify variation among and within populations in vulnerability to climate change and herbivory. We use long-term monitoring data to examine our overarching hypothesis that the negative impacts of poor soil and herbivore susceptibility would be compounded by severe drought. We studied pinyon pine, Pinus edulis, a widespread southwestern tree species that has suffered extensive climate-change related mortality. We analyzed data on mortality, growth, male reproduction, and herbivory collected for 14–32 years in three areas with distinct soil-types. We used standardized precipitation-evapotranspiration index (SPEI) as a climate proxy that summarizes the impacts of drought due to precipitation and temperature variation on semi-arid forests. Several key findings emerged: (1) Plant performance measurements did not support our hypothesis that trees growing in stressful, coarse-textured soils would suffer more than trees growing in finer-textured soils. Stem growth at the area with coarse, young cinder soils (area one) responded only weakly to drought, while stem growth on more developed soils with sedimentary (area two) and volcanic (area three) substrates, was strongly negatively affected by drought. Male reproduction declined less with drought at area one and more at areas two and three. Overall mortality was 30% on coarse cinder soils (area one) and averaged 55% on finer soil types (areas two and three). (2) Although moth herbivore susceptible trees were hypothesized to suffer more with drought than moth resistant trees, the opposite occurred. Annual stem growth was negatively affected by drought for moth resistant trees, but much less strongly for moth susceptible trees. (3) In contrast to our hypothesis, moths declined with drought. Overall, chronically water-stressed and herbivore-susceptible trees had smaller declines in performance relative to less-stressed trees during drought years. These long-term findings support the idea that stressed trees might be more resistant to drought since they may have adapted or acclimated to resist drought-related mortality.

Arizona's Sunset Crater began erupting in 1064 AD and for the next 200 years buried over 2,000 km2 in ash, cinders, and lava. Soil analyses indicate that pinyon pines (Pinus edulis) currently colonizing the cinder fields are faced with a highly stressful environment. Many of these pinyons suffer chronic, intense insect herbivory that reduces plant growth and eliminates female cone production. In contrast, herbivory among pinyons growing in neighboring sandy-loam soils is minimal. Furthermore, numerous trees within the heavily infested cinder field population suffer relatively low herbivory and maintain normal growth and reproduction. We used four polymorphic enzymes to examine the relationship between herbivore attack, environmental stress and genotypes of the adjacent cinder field, and sandy-loam soil pinyon populations. Our results demonstrate that 1) resistant trees display significant genetic differences and are more heterozygous for two enzymes associated with herbivory than susceptible trees; and 2) the cinder-soil pinyons exhibit significant genetic differences and are more heterozygous for an enzyme associated with environmental stress than the neighboring sandy-loam soil pinyons. We conclude that heterozygosity of specific or closely linked loci may facilitate pinyon resistance to herbivory and environmental stress, and that strong selection across narrow geographic boundaries resulted in rapid genetic differentiation of pinyon populations.

PREMISE OF THE STUDY Iris pseudacorus spread rapidly into North America after introduction from Europe in the 1800s and now co-occurs with native I. hexagona in freshwater Louisiana wetlands. Native irises support and interact with multiple trophic levels, whereas I. pseudacorus is classified an invasive pest because it grows aggressively, reduces biodiversity, and displaces native vegetation. Salinity levels are increasing in coastal wetlands worldwide. We examined how salt-stress affects competitive interactions between these conspecifics. METHODS We established a three-way full-factorial common-garden experiment that included species (I. pseudacorus, I. hexagona), competition (no competition, intraspecific competition, and interspecific competition), and salinity (0, 4, 8 parts per thousand NaCl), with six replicates per treatment. KEY RESULTS After 18 mo, Iris pseudacorus produced much more biomass than the native species did (F1, 92 = 71.5, P < 0.0001). Interspecific competition did not affect the introduced iris, but biomass of the native was strongly reduced (competition × species interaction: F2, 95 = 76.7, P = 0.002). Salinity significantly reduced biomass of both species (F2, 92 = 21.8, P < 0.0001), with no species × salinity interaction (F2, 84 = 1.85, P = 0.16). CONCLUSIONS Our results demonstrate that salt stress strongly reduced clonal reproduction in native and introduced irises; however, the introduced iris had a competitive advantage over the native, regardless of environmental salinity levels. Based on patterns in clonal reproduction, the introduced iris could potentially threaten native iris populations. We are currently investigating seed production and mortality during competition and stress because both clonal and sexual reproduction must be considered when predicting long-term population dynamics.