Thermally moderated firefly activity is delayed by precipitation extremes

Coexistence between similar invaders: The case of two cosmopolitan exotic insects

Biological invasions are usually examined in the context of their impacts on native species. However, few studies have examined the dynamics between invaders when multiple exotic species successfully coexist in a novel environment. Yet, long-term coexistence of now established exotic species has been observed in North American lady beetle communities. Exotic lady beetles Harmonia axyridis and Coccinella septempunctata were introduced for biological control in agricultural systems and have since become dominant species within these communities. In this study, we investigated coexistence via spatial and temporal niche partitioning among H. axyridis and C. septempunctata using a 31-year data set from southwestern Michigan, USA. We found evidence of long-term coexistence through a combination of small-scale environmental, habitat, and seasonal mechanisms. Across years, H. axyridis and C. septempunctata experienced patterns of cyclical dominance likely related to yearly variation in temperature and precipitation. Within years, populations of C. septempunctata peaked early in the growing season at 550 degree days, while H. axyridis populations grew in the season until 1250 degree days and continued to have high activity after this point. C. septempunctata was generally most abundant in herbaceous crops, whereas H. axyridis did not display strong habitat preferences. These findings suggest that within this region H. axyridis has broader habitat and abiotic environmental preferences, whereas C. septempunctata thrives under more specific ecological conditions. These ecological differences have contributed to the continued coexistence of these two invaders. Understanding the mechanisms that allow for the coexistence of dominant exotic species contributes to native biodiversity conservation management of invaded ecosystems.

Some Abiotic and Biotic Factors Influencing Firefly Population Abundance in Southeast Asia: A Review

This paper reviews biotic and abiotic factors that influence the life cycle of fireflies. This review paper has screened and chosen articles by using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) from two databases: Semantic Scholar (n = 1080) and Google Scholar (n = 2280). From this review, generally, abiotic factors, i.e., water level in soil, air temperature, air humidity, rainy season, altitude, water salinity (NaCl), wind direction, wind speed, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonia nitrogen (NH3-N) and maximum air pollution index (API) were most likely influenced the population abundance and distribution of the fireflies in Southeast Asia. Biotic factors include the presence of <i>Cyclotropis carinata</i> snails, vegetation health, tree suitability (leaf size, density, arrangement of leaves, tree location), insecticides (Saponins) in some vegetation species, plant structural architecture, and food (nectar and sap) were the most likely to influence the presence of fireflies species even though synchronous firefly of Southeast Asia were found in other vegetation species, <i>Sonneratia caseolaris</i> (Berembang) still the most preferred display tree. From this review, we also found that Malaysia has the highest reported findings on firefly studies in this region. To conclude, numerous abiotic and biotic elements should be researched further to determine their relationship to firefly populations and other vertebrate - invertebrates in their natural environment.

Species-Specific Flash Patterns Track the Nocturnal Behavior of Sympatric Taiwanese Fireflies

It is highly challenging to evaluate the species' content and behavior changes in wild fireflies, especially for a sympatric population. Here, the flash interval (FI) and flash duration (FD) of flying males from three sympatric species (Abscondita cerata, Luciola kagiana, and Luciola curtithorax) were investigated for their potentials in assessing species composition and nocturnal behaviors during the A. cerata mating season. Both FI and FD were quantified from the continuous flashes of adult fireflies (lasting 5-30 s) via spatiotemporal analyses of video recorded along the Genliao hiking trail in Taipei, Taiwan. Compared to FD patterns and flash colors, FI patterns exhibited the highest species specificity, making them a suitable reference for differentiating firefly species. Through the case study of a massive occurrence of A. cerata (21 April 2018), the species contents (~85% of the flying population) and active periods of a sympatric population comprising A. cerata and L. kagiana were successfully evaluated by FI pattern matching, as well as field specimen collections. Our study suggests that FI patterns may be a reliable species-specific luminous marker for monitoring the behavioral changes in a sympatric firefly population in the field, and has implication values for firefly conservation.

Why are there so many bee-orchid species? Adaptive radiation by intra-specific competition for mnesic pollinators

Adaptive radiations occur mostly in response to environmental variation through the evolution of key innovations that allow emerging species to occupy new ecological niches. Such biological innovations may play a major role in niche divergence when emerging species are engaged in reciprocal ecological interactions. To demonstrate coevolution is a difficult task; only a few studies have confirmed coevolution as driver of speciation and diversification. Herein we review current knowledge about bee orchid (Ophrys spp.) reproductive biology. We propose that the adaptive radiation of the Mediterranean orchid genus Ophrys, comprising several hundred species, is due to coevolutionary dynamics between these plants and their pollinators. We suggest that pollination by sexual swindling used by Ophrys orchids is the main driver of this coevolution. Flowers of each Ophrys species mimic a sexually receptive female of one particular insect species, mainly bees. Male bees are first attracted by pseudo-pheromones emitted by Ophrys flowers that are similar to the sexual pheromones of their females. Males then are lured by the flower shape, colour and hairiness, and attempt to copulate with the flower, which glues pollen onto their bodies. Pollen is later transferred to the stigma of another flower of the same Ophrys species during similar copulation attempts. In contrast to rewarding pollination strategies, Ophrys pollinators appear to be parasitized. Here we propose that this apparent parasitism is in fact a coevolutionary relationship between Ophrys and their pollinators. For plants, pollination by sexual swindling could ensure pollination efficiency and specificity, and gene flow among populations. For pollinators, pollination by sexual swindling could allow habitat matching and inbreeding avoidance. Pollinators might use the pseudo-pheromones emitted by Ophrys to locate suitable habitats from a distance within complex landscapes. In small populations, male pollinators would disperse once they have memorized the local diversity of sexual pseudo-pheromone bouquets or if all Ophrys flowers are fertilized and thus repel pollinators via production of repulsive pheromones that mimic those produced by fertilized female bees. We propose the following evolutionary scenario: Ophrys radiation is driven by strong intra-specific competition among Ophrys individuals for the attraction of species-specific pollinators, which is a consequence of the high cognitive abilities of pollinators. Male bees record the pheromone signatures of kin or of previously courted partners to avoid further copulation attempts, thereby inducing strong selection on Ophrys for variation in odour bouquets emitted by individual flowers. The resulting odour bouquets could by chance correspond to pseudo-pheromones of the females of another bee species, and thus attract a new pollinator. If such pollinator shifts occur simultaneously in several indivuals, pollen exchanges might occur and initiate speciation. To reinforce the attraction of the new pollinator and secure prezygotic isolation, the following step is directional selection on flower phenotypes (shape, colour and hairiness) towards a better match with the body of the pollinator's female. Pollinator shift and the resulting prezygotic isolation is adaptive for new Ophrys species because they may benefit from competitor-free space for limited pollinators. We end our review by proritizing several critical research avenues.

Nutrient dilution and climate cycles underlie declines in a dominant insect herbivore

Evidence for global insect declines mounts, increasing our need to understand underlying mechanisms. We test the nutrient dilution (ND) hypothesis-the decreasing concentration of essential dietary minerals with increasing plant productivity-that particularly targets insect herbivores. Nutrient dilution can result from increased plant biomass due to climate or CO₂ enrichment. Additionally, when considering long-term trends driven by climate, one must account for large-scale oscillations including El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO). We combine long-term datasets of grasshopper abundance, climate, plant biomass, and end-of-season foliar elemental content to examine potential drivers of abundance cycles and trends of this dominant herbivore. Annual grasshopper abundances in 16- and 22-y time series from a Kansas prairie revealed both 5-y cycles and declines of 2.1-2.7%/y. Climate cycle indices of spring ENSO, summer NAO, and winter or spring PDO accounted for 40-54% of the variation in grasshopper abundance, mediated by effects of weather and host plants. Consistent with ND, grass biomass doubled and foliar concentrations of N, P, K, and Na-nutrients which limit grasshopper abundance-declined over the same period. The decline in plant nutrients accounted for 25% of the variation in grasshopper abundance over two decades. Thus a warming, wetter, more CO₂-enriched world will likely contribute to declines in insect herbivores by depleting nutrients from their already nutrient-poor diet. Unlike other potential drivers of insect declines-habitat loss, light and chemical pollution-ND may be widespread in remaining natural areas.