Butterfly Response to Microclimatic Conditions Following Ponderosa Pine Restoration

Efforts to restore ponderosa pine ecosystems to open, park‐like conditions that predominated prior to European‐American settlement result in altered stand structure and increased landscape heterogeneity, potentially altering habitat suitability for invertebrates and other forest organisms. We examined the responses of two butterfly species, Colias eurytheme and Neophasia menapia, to microclimatic changes at structural edges created by experimental restoration treatments in northern Arizona. We monitored microclimate, including air temperature, light intensity, and vapor pressure deficit (VPD), on several mornings during butterfly releases. We placed adult butterflies at east‐ and west‐facing edges approximately one half‐hour before dawn to determine their behavioral response to microclimatic differences between east‐ and west‐facing edges. After sunrise, all three microclimatic variables were higher at east‐facing edges, and the difference in microclimate between the two edge orientations increased through early morning. For both species, butterflies placed at east‐facing edges flew earlier than butterflies at west‐facing edges. Colias eurytheme, an open‐habitat species, tended to move toward the treated forest during initial flight, while movements of Neophasia menapia, a forest‐dwelling species, did not differ from random flight. Our results indicate that butterflies respond to microclimatic factors associated with restoration treatments, while responses to structural changes in habitat vary among species, based on habitat and food plant preferences. These changes in forest structure and microclimate may affect the distribution of many mobile invertebrates in forested landscapes undergoing restoration treatments.     

Interrelation of mating,flight, and fecundity in navel orangeworm females

The navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae, Phycitini), is an economically important pest of nut crops in California, USA. Improved management will require better understanding of insect dispersal, particularly relative to when mating occurs. A previous study demonstrated a more robust laboratory flight capacity compared to other orchard moth pests, but it was unclear how mating affects dispersal, and how dispersal affects fecundity. In this study, 1‐ and 2‐day‐old females were allowed to fly overnight on a flight mill either before or after mating, respectively, and were then allowed to oviposit. Data on fecundity were compared between treatments to minimally handled or tethered‐only control females. Females that mated before flight flew longer and covered a greater distance than those flying prior to mating. However, timing of flight relative to mating did not affect fecundity, nor did any measure of flight performance. There was no effect on fecundity when females were forced to fly for designated durations from 3 min to 2 h. Together, our data revealed no obvious trade‐off between flight activity and reproductive output. Distances measured on the flight mills (mean ca. 15 km for mated females) may overestimate net displacement in the field where flight tracks are often meandering. The results suggest that most females mate and oviposit in or near their natal habitat, but that some may disperse potentially long distances to oviposit elsewhere.     

Antipredator behaviour of African ungulates around human settlements

As human populations grow and come into more frequent contact with wildlife, it is important to understand how anthropogenic disturbance alters wildlife behaviour. Using fine‐scale spatial analyses, we examined how proximity to human settlements affects antipredator responses of ungulates. We studied seven common ungulate species (Kirk's dik‐dik, Thomson's gazelle, impala, common warthog, common wildebeest, common zebra and Masai giraffe) in the Tarangire–Manyara ecosystem in northern Tanzania. In zebra and giraffe, flight responses to humans were significantly more likely when closer to settlements; however, there was a weak relationship between flight responses and distance to settlement in all other species. While there was largely a weak relationship between proximity to human settlements, the distribution of settlements in the landscape appears to affect wildlife behaviour, suggesting that animals perceive and respond to spatial variation in risk exerted by humans.     

Molecular mechanism of Arabidopsis thaliana profilins as antifungal proteins

Background

It remains an open question whether plant phloem sap proteins are functionally involved in plant defense mechanisms.

Feather holes and flight performance in the barn swallow Hirundo rustica

Feather holes are small (0.5–1?mm in diameter) deformities that appear on the vanes of flight feathers. Such deformities were found in many bird species, including galliforms and passerines. Holey flight feathers may be more permeable to air, which could have a negative effect on their ability to generate aerodynamic forces. However, to date the effects of feather holes on flight performance in birds remained unclear. In this study we investigated the relationship between the number of feather holes occurring in the wing or tail feathers and short term flight performance traits – aerial manoeuvrability, maximum velocity and maximum acceleration – in barns swallows, which are long distance migrating aerial foragers. We measured short-term flight performance of barn swallows in a standardized manner in flight tunnels. We found that acceleration and velocity were significantly negatively associated with the number of holes in the wing flight feathers, but not with those in the tail feathers. In the case of acceleration the negative relationship was sex specific – while acceleration significantly decreased with the number of feather holes in females, there was no such significant association in males. Manoeuvrability was not significantly associated with the number of feather holes. These results are consistent with the hypothesis that feather holes are costly in terms of impaired flight. We discuss alternative scenarios that could explain the observed relationships. We also suggest directions for future studies that could investigate the exact mechanism behind the negative association between the number of feather holes and flight characteristics.     

Environmental conditions for Diaphorina citri Kuwayama (Hemiptera: Liviidae) take‐off

Environmental factors that influence flight activity of Diaphorina citri Kuwayama (Hemiptera: Liviidae) may have implications for Huanglongbing spread and management. In this work, four studies were conducted to evaluate the effect of environmental conditions on D. citri take‐off. In the first, insects were transferred to sweet orange seedlings and confined inside an acrylic cage to verify the take‐off periodicity and the effect of environmental factors on this process. In the second, take‐off temperature threshold was estimated by recording the number of insects that initiated flight from a platform when subjected to gradual temperature increases from 15 to 39°C. In the other studies, we evaluated the effect of different photoperiods and temperature regimes (third study) and of constant temperatures (fourth study) on the propensity for D. citri flight. Insects were confined in clear plastic bottle cages with tubes of 50 ml placed on the cab, to collect emerged adults that initiated flights. Results showed that a small portion of the tested population (maximum 10%) tends to take off from plants and this behaviour is more prevalent in the afternoon (14:00–16:00 h), coinciding with daytimes of lower humidity and higher thermal amplitude. Adults that were submitted to lower temperatures (18°C) and short light periods (10 h) showed less propensity to flight. In contrast, at constant 27°C, the insects were more prone to flight, and this result was confirmed when individuals were submitted to increases in temperature, indicating that 27.14°C is the take‐off temperature threshold of D. citri. Results show that temperature plays an important role in the flight activity of D. citri and suggest that control measures of the insect may be more effective in the morning and in temperatures below 27°C, when the probability to take off from a host is lower.     

An ordinal day model of spruce beetle trap capture phenology in northern Colorado

Spruce beetle populations (Dendroctonus rufipennis) (Coleoptera: Scolytinae) in Engelmann spruce (Picea engelmannii) stands were monitored at twelve sites for 6 years in northern Colorado using pheromone‐baited Lindgren funnel traps. During the trapping period, over 30,000 beetles were captured, and beetle abundance data were used to construct empirical models of trap capture phenology based on day of year, accumulation of thermal units and thermal day thresholds, with the goal of informing future regional trapping efforts and producing a simple model for use by forest managers. Ordinal day models outperformed thermal accumulation and thermal threshold models in both predictive power and parsimony. Mean date of earliest capture was Day 153 (June 2) and ranged from Day 126 to Day 161 (May 6–June 10), and mean date of final capture was Day 243 (August 31) and ranged from Day 220 to Day 286 (August 8–October 13). A two‐parameter logistic function was the most parsimonious of several ordinal day models, accounting for 81% of the variance in cumulative trap capture across all sites and dates. The model predicts 50% of trap captures to occur by Day 181 (June 30). This model has application as a decision support tool for forest ecosystem managers concerned with the timing of trap deployment or D. rufipennis mitigation treatments.     

Comparison of the performance of Cicadulina leafhoppers on flight mills with that to be expected in free flight

Flight mills are commonly used to assess the relative flight performance of migratory insects, but uncertainties about the rate of energy expenditure on the mill mean that absolute estimates of flight endurance are not usually attempted. In this paper we describe how we measured the power delivered to a lightweight flight mill by tethered Cicadulina storeyi China leafhoppers (Homoptera: Cicadellidae), and compared this to estimates of the power they use to maintain free flight. Our results showed that the leafhoppers were generating more than 0.90 W of mechanical power when on the mill, and that they probably have 3–4 W available for free flight. We conclude that whilst flying on the mill, the insects were generating at least 20–30% of the mechanical power needed for free flight, and that this percentage may have been significantly higher.     

Prediction of flight of apple sawfly, Hoplocampa testudinea, using temperature sums

A method to predict the beginning of the flight of apple sawfly, Hoplocampa testudinea (Klug) (Hymenoptera, Tenthredinidae) is presented. Adults were monitored during 8 years at the experimental orchard De Schuilenburg, Kesteren, The Netherlands, with visual sticky traps. Temperature sums, accumulated until the day of the first capture of sawfly, were calculated for different starting dates of the summations. Beginning on 1 January, variation of the temperature sums, calculated in each of 8 years, decreased when later starting dates for temperature summation were chosen, reaching a minimum on 1 April for soil temperatures (–5 cm). The soil temperature sum, accumulated from 1 April until the first capture, was on average 134 day-degrees above a threshold of 4 °C. So this was the most suitable starting date to predict the beginning of sawfly flight activity. As use of the summation method based on air temperatures is in practice more appropriate for timing of trap installation by extension services and apple growers, trap deployment is recommended at an adapted value of 157 day-degrees from 15 March.