The nectar alkaloid, gelsemine, does not affect offspring performance of a native solitary bee, Osmia lignaria (Megachilidae)

Abstract.  1. The ecology and evolution of foliar-feeding insects are thought to be closely tied to plant secondary compounds. Although secondary compounds are also abundant in floral nectar, their role in mediating pollinator preference and performance remains relatively unexplored.
2. This study tested the effects of an alkaloid, gelsemine, found in the nectar of Carolina jessamine ( Gelsemium sempervirens L., Loganiaceae), on the performance of a native solitary bee ( Osmia lignaria lignaria Say, Megachilidae). Nectar gelsemine reduces visits from pollinators, including O. lignaria lignaria , and gelsemine is toxic to vertebrates and possibly non-native honey bees ( Apis mellifera L., Apidae). To test the hypothesis that the deterrent effects of nectar gelsemine reflect negative consequences for pollinator performance, O. lignaria lignaria offspring provisions were supplemented with nectar containing different gelsemine concentrations. Effects on larval development time, prepupa cocoon mass, adult emergence, and adult mass were measured.
3. Nectar gelsemine had no effect on any measure of offspring performance. Thus, although gelsemine deters foraging by adult bees, this behaviour did not optimize offspring performance under the experimental conditions of this study. In contrast, sugar added to nectar treatments increased offspring mass.
4. While adult pollinators may avoid nectar with secondary compounds, this could hinder offspring performance by reducing sugar in provisions if nectar is limiting in the environment. Preference-performance trade-offs, which are studied extensively with foliar herbivores, have seldom been tested for pollinating plant consumers. Future studies of nectar secondary compounds and insect pollinator preference and performance may help to integrate studies of foliage-consuming insect herbivores with nectar-consuming insect pollinators.     

Foraging and nesting behavior of Osmia lignaria (Hymenoptera: Megachilidae) in the presence of fungicides: cage studies

During orchard pollination studies in California, we observed dramatic changes in nesting and foraging behavior of Osmia lignaria Say (Hymenoptera: Megachilidae) after sprays with tank mixtures containing fungicides. A characteristic pattern of postspray events observed includes erratic behavior and interrupted foraging and nesting activity for several days. In an effort to determine whether fungicidal sprays were disruptive to bee foraging and thus to pollination, we exposed O. lignaria females nesting in field cages planted with lacy scorpionweed, Phacelia tanacetifolia Benth (Hydrophyllaceae), to selected spray mixtures normally encountered in California orchard production systems: iprodione (Rovral), propiconazole (Orbit), benomyl (Benlate), and captan (Captan 50 WP); the surfactant Dyne-Amic, alone and mixed with Rovral; and the tank mixture IDB (Rovral + Dyne-Amic + the foliar fertilizer Bayfolan Plus). An additional cage sprayed with an equal volume of water acted as control, and a cage sprayed with the insecticide dimethoate as a toxic standard. For each female O. lignaria, we recorded time spent inside the nest depositing pollen-nectar loads, foraging time, cell production rate, and survival. All females in the dimethoate treatment died postspray + 1 d. Before death, some of these females behaved similarly to our previous orchard observations. A high proportion of females in the IDB cage were inactive for a few hours before resuming normal foraging and nesting activity. No lethal or behavioral effects were found for any of the other compounds or mixtures tested. Our results indicate that the fungicide applications that we tested are compatible with the use of O. lignaria as an orchard pollinator.     

Developing and establishing bee species as crop pollinators: the example of Osmia spp. (Hymenoptera: Megachilidae) and fruit trees

The development of a bee species as a new crop pollinator starts with the identification of a pollination-limited crop production deficit and the selection of one or more candidate pollinator species. The process continues with a series of studies on the developmental biology, pollinating efficacy, nesting behaviour, preference for different nesting substrates, and population dynamics of the candidate pollinator. Parallel studies investigate the biology of parasites, predators and pathogens. The information gained in these studies is combined with information on the reproductive biology of the crop to design a management system. Complete management systems should provide guidelines on rearing and releasing methods, bee densities required for adequate pollination, nesting materials, and control against parasites, predators and pathogens. Management systems should also provide methods to ensure a reliable pollinator supply. Pilot tests on a commercial scale are then conducted to test and eventually refine the management system. The process culminates with the delivery of a viable system to manage and sustain the new pollinator on a commercial scale. The process is illustrated by the development of three mason bees, Osmia cornifrons (Radoszkowski), O. lignaria Say and O. cornuta (Latreille) as orchard pollinators in Japan, the USA and Europe, respectively.     

Bee population returns and cherry yields in an orchard pollinated with Osmia lignaria (Hymenoptera: Megachilidae)

During 1998-2003, we used populations of the solitary bee Osmia lignaria Say to pollinate a commercial sweet cherry orchard in northern Utah. Bee densities released each year ranged from 1290 to 1857 females/ha, with approximately twice as many males. Female progeny produced each year were greater than parental populations released, except in 2003, when nesting was poor due to bird predation. Despite poor weather during bloom, and in contrast to most other local producers, the study orchard produced harvestable crops in 1999 (2,964 kg/ha) and 2001 (3,154 kg/ha). In 1998 and 2000, record yields were obtained (10,625 and 12,096 kg/ha, respectively). Including only those years with harvestable crops, average production was 2.2 times higher in 1998-2003 (when O. lignaria populations were used) compared with 1992-1997 (when 10 Apis mellifera hives were used). This is the first study reporting multiyear cherry yields in an orchard pollinated with O. lignaria in North America.     

Lethal and sublethal effects of imidacloprid on Osmia lignaria and clothianidin on Megachile rotundata (Hymenoptera: Megachilidae)

We examined lethal and sublethal effects of imidacloprid on Osmia lignaria (Cresson) and clothianidin on Megachile rotundata (F.) (Hymenoptera: Megachilidae). We also made progress toward developing reliable methodology for testing pesticides on wild bees for use in pesticide registration by using field and laboratory experiments. Bee larvae were exposed to control, low (3 or 6 ppb), intermediate (30 ppb), or high (300 ppb) doses of either imidacloprid or clothianidin in pollen. Field experiments on both bee species involved injecting the pollen provisions with the corresponding pesticide. Only O. lignaria was used for the laboratory experiments, which entailed both injecting the bee's own pollen provisions and replacing the pollen provision with a preblended pollen mixture containing imidacloprid. Larval development, emergence, weight, and mortality were monitored and analyzed. There were no lethal effects found for either imidacloprid or clothianidin on O. lignaria and M. rotundata. Minor sublethal effects were detected on larval development for O. lignaria, with greater developmental time at the intermediate (30 ppb) and high doses (300 ppb) of imidacloprid. No similar sublethal effects were found with clothianidin on M. rotundata. We were successful in creating methodology for pesticide testing on O. lignaria and M. rotundata; however, these methods can be improved upon to create a more robust test. We also identified several parameters and developmental stages for observing sublethal effects. The detection of sublethal effects demonstrates the importance of testing new pesticides on wild pollinators before registration.     

Influence of rough handling on Osmia lignaria (Hymenoptera: Megachilidae) nest establishment in commercial orchards

Osmia lignaria Say (Hymenoptera: Megachilidae) can be used to pollinate fruit trees. Populations are sometimes difficult to sustain because some female bees fail to establish at provided nesting sites. We address the hypothesis that rough handling of overwintered O. lignaria results in decreased establishment. We tested this by shaking (200 rpm for 2 min) overwintering bees as a proxy for rough handling. Bees were then released in an orchard, and nest establishment of shaken and unshaken bees was recorded. There was no significant difference in the proportion of shaken and unshaken females that nested, indicating that rough handling of overwintering bees does not discourage nest establishment.     

Modeling spring emergence of Osmia cornifrons Radoszkowski (Hymenoptera: Megachilidae) females in Korea

The Japanese hornfaced bee, Osmia cornifrons Radoszkowski (Hymenoptera: Megachilidae), is an important pollinator of apple. It overwinters as diapausing adult in cocoon and the synchronization of the adult emergence in spring with apple blossom is critical for successful pollination, specifically in the environment with variable climate. To this end, prediction model of adult emergence would help manage O. cornifrons populations for planed pollination. In this study, by using temperature-dependent emergence data of O. cornifrons, emergence rate were mathematically described using linear and Lactin's nonlinear regression methods. The lower emergence thresholds estimated from linear regression for female was 7.98 °C and the thermal constant (DD, degree days) was 112.43DD. Pattern of emergence completion was described by using Weibull function and prediction of spring emergence was modeled based on functions of emergence rate and distribution. The model predicted the emergence of O. cornifrons between 100–130 Julian date and the observation fell between 108–129 Julian date. The prediction ranges of O. cornifrons emergence were wider than that of observation. This model could help predict spring emergence of O. cornifrons in the field and optimize planed pollination program for pollination service in agricultural systems in the climate change era.     

Supercooling points and diapause termination in overwintering adults of orchard bees Osmia cornuta and O. rufa (Hymenoptera: Megachilidae)

The orchard bee species Osmia cornuta (Latreille) and O. rufa (Linnaeus) are both European in distribution. Osmia cornuta is distributed in the central and southern half of the continent, while O. rufa is distributed additionally in more northern parts of Europe, including Great Britain. These bees over-winter in cocoons as diapausing adults. The freezing temperatures of overwintering adults of O. cornuta and O. rufa during diapause are similar: -30 degrees C to -24 degrees C and -31 degrees C to -26 degrees C, respectively. However, there are differences in the termination of their diapause. Under natural conditions in the wider area of Belgrade, O. rufa appears in spring about two weeks later than O. cornuta.     

Effects of temperature on the immature development of the stone leek leafminer Liriomyza chinensis (Diptera: Agromyzidae)

The effect of nine constant temperatures (15, 17.5, 20, 22.5, 25, 27.5 30, 32.5, and 35 degrees C) on the development of the stone leek leafminer, Liriomyza chinensis (Kato), on Japanese bunching onion, Allium fistulosum L., was studied in the laboratory. Developmental times for immature stages were inversely proportional to temperature between 15 and 30 degrees C but increased at 32.5 degrees C. Total developmental times from egg to adult emergence decreased from 69.6 to 17.1 d for temperatures from 15 to 30 degrees C, with pupae requiring more time for development than the combined egg and larva stages. Both linear and nonlinear (Logan equation VI) models provided a reliable fit of development rates versus temperature for all immature stages. The lower developmental thresholds that were estimated from linear regression equations for the egg, first, second, and third instars, total larva, egg-larval, pupa, and total combined immature stages were 12.1, 10.6, 13.6, 8, 9.6, 11.3, 11.2, and 11.4 degrees C, respectively. The degree-day accumulation was calculated as 312.5 DD for development from egg to adult emergence. By fitting the nonlinear models to the data, the upper and optimal temperatures for egg, larva, pupa, and total immature stages were calculated as 37.8 and 31.7, 34.9 and 30.1, 35.8 and 30.6, and 35.0 and 30.9 degrees C, respectively. These data are useful for predicting population dynamics of L. chinensis under field conditions and determining the maximum proportion of susceptible individuals for facilitating improved timing of application of control measures.     

Effects of temperature on energy cost and timing of embryonic and larval development of the terrestrially breeding moss frog, Bryobatrachus nimbus

The Australian moss frog, Bryobatrachus nimbus, oviposits four to 16 large eggs in terrestrial nests constructed in moss or lichen in subalpine regions of southern Tasmania. Nidicolous larvae overwinter beneath snow, reaching metamorphosis without feeding after 395 d, the longest development time known for an endotrophic anuran. However, a few clutches develop more quickly and metamorphose before winter. This study examines the effect of temperature on development time and energy expenditure by measuring temperatures and developmental stages in field nests as well as rates of oxygen consumption (Vo2), developmental stage, body mass, and energy content in the laboratory at three relevant temperatures (5 degrees, 10 degrees, 15 degrees C). Eggs and larvae reared at 5 degrees C differentiated very slowly, and their development time far exceeded those in natural nests, but development times at 10 degrees and 15 degrees C averaged 277 and 149 d, respectively, and were shorter than field incubation times. Generally, respiration rates of aquatic hatchlings were low in comparison with other species but increased with larval age and jumped about 25% higher near metamorphosis when larvae were able to air breathe. The mean energy density was 26.0 J mg(-1) for the dry ova and 20.6 J mg(-1) for a dry gut-free froglet, and total production efficiency was 61.5%. We developed a model based on the relationships between incubation temperature and V&d2;o2 to estimate the respiratory cost of development to metamorphosis, the first such study for an amphibian. The cost was 177 J at 15 degrees C, 199 J at 10 degrees C, and at least 249 J at 5 degrees C, and we predicted that continual development at 5 degrees C would lead to premature yolk depletion because it equalled the 249 J contained in fresh ova. Continuously logged field-nest temperatures and interpolation of laboratory data provided estimates of development rates, Vo2, and respiratory energy costs in field nests. Development to metamorphosis required between 185 and 234 J when larvae overwintered, but completion of metamorphosis before winter saved 123 J. However, the advantage of emergence in warmer months, when conditions are suitable for feeding and growth, may offset the greater energy cost of overwintering.     

Nest‐to‐nest dispersal of Chaetodactylus krombeini (Acari,Chaetodactylidae) associated with Osmia cornifrons (Hym., Megachilidae)

A cleptoparasitic mite, the Krombein’s hairy‐footed mite, Chaetodactylus krombeini Baker (Acari, Chaetodactylidae) became a key pest that affects the maintenance and propagation of Osmia spp. (Hym., Megachilidae), thus disrupting orchard pollination in the United States. Although hypopi, the dispersal stages of C. krombeini, are known to disperse from nest to nest by hitchhiking on Osmia cornifrons adults, we observed that they might disperse in other ways too in commercial orchards. This study was conducted to elucidate the nest‐to‐nest dispersal mechanisms of C. krombeini hypopi. We tested three potential dispersal mechanisms of C. krombeini other than phoresy by O. cornifrons: (1) dispersal by walking from nest to entrances of nearby nests, (2) dispersal by walking from nest to nest through emergence holes made by parasitic wasps on nests, and (3) dispersal by being unloaded and uptaken to and from flowers by O. cornifrons. Results of this study showed that C. krombeini hypopi could disperse from a nest to nearby nests by walking through nest entrances and holes made by parasitic wasps of O. cornifrons. Although 0.06% of C. krombeini hypopi on blueberry flowers were picked up by O. cornifrons, they were not able to be unloaded to flowers from O. cornifrons and no hypopi could inhabit or survive on blueberry flowers. This indicated no or very low chance of C. krombeini hypopi dispersal via blueberry flowers. Based on our findings of C. krombeini dispersal ecology, development of C. krombeini control strategies are discussed in this article.     

Phenotypic responses of hatchlings to constant versus fluctuating incubation temperatures in the multi-banded krait, Bungarus multicintus (Elapidae)

Most studies on egg incubation in reptiles have relied on constant temperature incubation in the laboratory rather than on simulations of thermal regimes in natural nests. The thermal effects on embryos in constant-temperature studies often do not realistically reflect what occurs in nature. Recent studies have increasingly recognized the importance of simulating natural nest temperatures rather than applying constant-temperature regimes. We incubated Bungarus multicintus eggs under three constant and one fluctuating-temperature regimes to evaluate the effects of constant versus fluctuating incubation temperatures on hatching success and hatchling phenotypes. Hatching success did not differ among the four treatments, and incubation temperature did not affect the sexual phenotype of hatchlings. Incubation length decreased as incubation temperature increased, but eggs incubated at fluctuating temperatures did not differ from eggs incubated at constant temperatures with approximately the same mean in incubation length. Of the hatchling phenotypes examined, residual yolk, fat bodies and locomotor performance were more likely affected by incubation temperature. The maximal locomotor speed was fastest in the fluctuating-temperature and 30 degrees C treatments and slowest in the 24 degrees C treatment, with the 27 degrees C treatment in between. The maximal locomotor length was longest in the fluctuating-temperature treatment and shortest in the 24 degrees C and 27 degrees C treatments, with the 30 degrees C treatment in between. Our results show that fluctuating incubation temperatures do not influence hatching success and hatchling size and morphology any differently than constant temperatures with approximately the same mean, but have a positive effect on locomotor performance of hatchlings.     

Biphasic effect of low temperature on completion of winter diapause in the onion maggot,Delia antiqua

The effect of low temperature on completion of winter diapause was investigated in the onion maggot, Delia antiqua (Diptera: Anthomyiidae). Diapause was completed under constant diapause-inducing conditions of 15 degrees C and 12L-12D, without any exposure to lower temperature. The pupal period for 50% adult emergence was 117 days. None of the cold treatments at 5.6 degrees C examined in the present study advanced adult emergence; on the contrary, they delayed it. Detailed analyses of the results revealed that diapause development in D. antiqua comprises two phases which differ in sensitivity to low temperature, with the phase shift occurring at around day 60 at 15 degrees C and 12L-12D. In the first phase of diapause development, low temperature (5.6 degrees C) had no effect on diapause development. In the latter phase, by contrast, diapause development was retarded in proportion to the duration of cold treatment.     

Wildflower plantings promote blue orchard bee,Osmia lignaria (Hymenoptera: Megachilidae), reproduction in California almond orchards

Concerns over the availability of honeybees (Apis mellifera L.) to meet pollination demands have elicited interest in alternative pollinators to mitigate pressures on the commercial beekeeping industry. The blue orchard bee, Osmia lignaria (Say), is a commercially available native bee that can be employed as a copollinator with, or alternative pollinator to, honeybees in orchards. To date, their successful implementation in agriculture has been limited by poor recovery of bee progeny for use during the next spring. This lack of reproductive success may be tied to an inadequate diversity and abundance of alternative floral resources during the foraging period. Managed, supplementary wildflower plantings may promote O. lignaria reproduction in California almond orchards. Three wildflower plantings were installed and maintained along orchard edges to supplement bee forage. Plantings were seeded with native wildflower species that overlapped with and extended beyond almond bloom. We measured bee visitation to planted wildflowers, bee reproduction, and progeny outcomes across orchard blocks at variable distances from wildflower plantings during 2015 and 2016. Pollen provision composition was also determined to confirm O. lignaria wildflower pollen use. Osmia lignaria were frequently observed visiting wildflower plantings during, and after, almond bloom. Most O. lignaria nesting occurred at orchard edges. The greatest recovery of progeny occurred along the orchard edges having the closest proximity (80 m) to managed wildflower plantings versus edges farther away. After almond bloom, O. lignaria nesting closest to the wildflower plantings collected 72% of their pollen from Phacelia spp., which supplied 96% of the managed floral area. Phacelia spp. pollen collection declined with distance from the plantings, but still reached 17% 800 m into the orchard. This study highlights the importance of landscape context and proximity to supplementary floral resources in promoting the propagation of solitary bees as alternative managed pollinators in commercial agriculture.     

Effects of temperature and humidity on emergence dynamics of Plutella xylostella (Lepidoptera: Plutellidae)

The effects of temperature and humidity on the emergence patterns of diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), were studied at four temperatures (20, 25, 28, and 33 degrees C),three relative humidities (50, 70, and 90%) and a photoperiod of 14:10 (L:D) h. Both sexes emerged primarily in the late afternoon to early morning, and the peaks of emergence varied depending on temperature and humidity. Females emerged significantly earlier than males. Incubation at 33 degrees C and 90% RH had a significant effect on the emergence rate, but no significant interaction was found between temperature and humidity. Emergence duration was 25.3 h for both sexes at 90% RH, with emergence duration at 33 degrees C lower than the other treatments. The sex ratios of diamondback moth under different temperature and humidity treatments were approximately 1:1, and there were no significant effects of temperature and humidity or interactions between these two factors.     

Experience-dependent plasticity in the mushroom bodies of the solitary bee Osmia lignaria (Megachilidae)

All members of the solitary bee species Osmia lignaria (the orchard bee) forage upon emergence from their natal nest cell. Conversely, in the honey bee, days-to-weeks of socially regulated behavioral development precede the onset of foraging. The social honey bee's behavioral transition to foraging is accompanied by neuroanatomical changes in the mushroom bodies, a region of the insect brain implicated in learning. If these changes were general adaptations to foraging, they should also occur in the solitary orchard bee. Using unbiased stereological methods, we estimated the volume of the major compartments of the mushroom bodies, the neuropil and Kenyon cell body region, in adult orchard bees. We compared the mushroom bodies of recently emerged bees with mature bees that had extensive foraging experience. To separate effects of general maturation from field foraging, some orchard bees were confined to a cage indoors. The mushroom body neuropil of experienced field foragers was significantly greater than that of both recently emerged and mature caged orchard bees, suggesting that, like the honey bee, this increase is driven by outdoor foraging experience. Unlike the honey bee, where increases in the ratio of neuropil to Kenyon cell region occur in the worker after emerging from the hive cell, the orchard bee emerged from the natal nest cell with a ratio that did not change with maturation and was comparable to honey-bee foragers. These results suggest that a common developmental endpoint may be reached via different development paths in social and solitary species of foraging bees.     

Simple roost nests confer large energetic savings for sparrow-weavers

White-browed sparrow-weavers (Plocepasser mahali, body mass 40 g) are group-living passerines adapted to the semi-arid environment of north-eastern and south-western Africa. During winter, the nocturnal ambient temperature of these regions often falls below 0 degrees C. imposing conditions demanding an increase in thermoregulatory heat production. Individuals roost throughout the year in inverted U-shaped roost nests. We investigated the energetic advantages of roosting by measuring nest and ambient temperatures in the field, as well as the resting metabolic rate (RMR) of the birds. The sparrow-weavers exhibited a wide thermoneutral zone (13 degrees C - 32 degrees C). Although RMR at thermoneutrality (40.2 J g.h(-1)) conforms with those of other passerines. the value at 0 degrees C (74.8 J g.h(-1)) is significantly lower than expected. The slope of the line below the lower critical temperature is unexpectedly steep, however, and appears to cause the physiological requirement for nest roosting due to a high cost of thermoregulation at low temperatures, perhaps due to shivering or non-shivering thermogenesis. The nest temperature at 0 degrees C ambient is 5 degrees C. resulting in a saving of some 7% in the energy spent during winter nights when food resources are in short supply compared with the rest of the year.     

Influence of temperature on developmental rate,wing length,and larval head capsule size of pestiferous midge Chironomus crassicaudatus (Diptera: Chironomidae)

Larvae of Chironomus crassicaudatus Malloch were reared individually at nine constant temperatures from 12.5 to 32.5 degrees C (2.5 degrees C increments) for 120 d. Duration of immature stages (egg, four instars, and pupa), head capsule width of fourth instars, and wing length were recorded. Some adults emerged at all temperatures, except at 12.5 degrees C where individuals developed to fourth instars during the experiment. Sharpe and DeMichele's four-parameter model with high-temperature inhibition described the temperature-dependent developmental rates. The slowest development was observed at 15 degrees C, with developmental rate peaking between 25 and 27.5 degrees C. Developmental rate increased rapidly with increasing temperature up to 20 degrees C, slowed between 20 and 27.5 degrees C, and decreased at temperatures >27.5 degrees C. No developmental inhibition at high temperatures was observed in eggs. The most apparent high-temperature inhibition of development was recorded in fourth instars, which comprised the largest proportion of developmental time. Males developed faster than females, but females had wider larval head capsules and longer wings than males. Adult size was negatively related with temperature in both sexes, but this relationship was steeper in males than in females. Larval size peaked at 20 degrees C, whereas the head capsule width was reduced at temperatures higher and lower than 20 degrees C.     

Co-flowering plants support diverse pollinator populations and facilitate pollinator visitation to sweet cherry crops

Many food crops depend on animal pollination to set fruit. In light of pollinator declines there is growing recognition of the need for agro-ecosystems that can sustain wild pollinator populations, ensuring fruit production and pollinator conservation into the future. One method of supporting resident wild pollinator populations within agricultural landscapes is to encourage and maintain floral diversity. However, pollinator visitation to crop plants can be affected either positively (facilitation) or negatively (competition) by the presence of co-flowering plants. The strength and direction of the facilitative/competitive relationship is driven by multiple factors, including floral abundance and the degree of overlap in pollinator visitation networks. We sought to determine how plant-pollinator networks, within and surrounding sweet cherry (Prunus avium) orchards, change across key time points during the cherry flowering season, in three growing regions in Australia. We found significant overlap in the suite of flower visitors, with seven taxa (including native bees, flies, hoverflies and introduced honey bees, Apis mellifera) observed visiting cherry and other co-flowering species within the orchard and/or the wider surrounding matrix. We found evidence of pollinator facilitation with significantly more total cherry flower visits with increasing percent cover of co-flowering plants within the wider landscape matrix and increased visitation to cherry by honey bees with increasing co-flowering plant richness within the orchard. During the cherry flowering period there was a significant positive relationship between pollinator richness on cherry and pollinator richness on co-flowering plants within the orchard and the area of native vegetation surrounding orchards. Outside of the crop flowering season, co-flowering plants within the orchard and wider landscape matrix supported the same pollinator taxa that were recorded visiting cherry when the crop was flowering. This shows wild plants help support the pollinators important to crop pollination, outside of the crop flowering season, highlighting the role of co-flowering plants within pollinator-dependent cropping systems.     

The influence of pruning on wasp inhabitants of galls induced by Hemadas nubilipennis Ashmead (Hymenoptera: Pteromalidae) on lowbush blueberry

The efficacy of pruning methods for managing blueberry stem galls caused by the chalcid wasp, Hemadas nubilipennis (Ashmead), was studied in five commercial lowbush blueberry (Vaccinium angustifolium Aiton) fields in Nova Scotia, Canada, between October 1999 and May 2000. Blueberry fields were mowed in the fall, and burning treatments were subsequently applied either in the fall or the spring. Three treatments were compared: mowing only, mowing plus fall burning, and mowing plus spring burning. Galls collected from the mow plus spring-burn treatment had the least wasp emergence of the three treatments, while the total number of galls was not affected by treatment. Wasp mortality, not gall destruction, is why wasp emergence is reduced in burn treatments. More galls were located and, for the burn treatments, higher wasp emergence was seen from galls found within the leaf litter than those above it. Five co-inhabitants emerged from blueberry stem galls in this study. Three, Eurytoma solenozopheriae (Ashmead), Sycophila vacciniicola (Balduf), and Orymus vacciniicola (Ashmead) are commonly found associates. The other two, Eupelmus vesicularis (Ritzius) and Pteromalus spp., are new records for Nova Scotia. O. vacciniicola is likely an inquiline because it is the largest wasp emerging from galls, and there was a positive relationship between its emergence and that of H. nubilipennis. Larger gall size improved H. nubilipennis emergence from mow and spring-burn galls. After a field has been mowed in the fall, we recommend a spring burn to reduce gall populations and the threat of product contamination.