Field techniques for sampling and measuring the standing crop and secretion rate of nectar are de... more Field techniques for sampling and measuring the standing crop and secretion rate of nectar are described, in order to clarify some discrepancies and omissions in existing reviews of nectar measuring techniques. Slender microcapillary tubes (a fresh one for each sample) are recommended for withdrawing nectar, and a hand held sucrose refractometer, capable of operating with very small fluid volumes, is used for measuring concentration. Potential errors due to the presence of solutes other than sucrose, or to temperatures other than the calibration temperature, are discussed. I consider how measurements of secretion rate are affected by reabsorption and by the nature of the bags used to exclude nectarivores. standing crop / nectar concentration / secretion rate / microcap / refractometer / sucrose / glucose / fructose / amino acids / nectarivore
Only rarely have bumble bees (Bombus) been observed collecting honeydew from aphids (Aphididae) f... more Only rarely have bumble bees (Bombus) been observed collecting honeydew from aphids (Aphididae) feeding on phloem sap. This behavior may be rare because the percentage of sugar in honeydew egested from aphids is generally well below the sugar concentration in floral nectars preferred by bumble bees. Nonetheless, in August 2018, near St. Buryan, Penzance, Cornwall, UK (56.0602N; -5.6034W) we observed large numbers of wild Bombusterrestris (Linnaeus) collecting honeydew from a colony of the giant willow aphid Tuberolachnussalignus Gmelin feeding on the stems of the willow Salixalba. Unlike aphid-tending ants, who glean fresh honeydew directly from the aphid anal opening, the bumble bees were collecting honeydew from leaf litter below the aphid colony. We hypothesized that honeydew collected from exposed ground surfaces was more concentrated due to evaporation under ambient conditions than that released directly from the anus (fresh honeydew). We thus monitored sugar concentrations of ...
The British moth Eana incanana (Tortricidae) has been found to selectively metabolize the glycosi... more The British moth Eana incanana (Tortricidae) has been found to selectively metabolize the glycosidase inhibitor 2R, 3R, 4R, 5R-2,5-dihydroxymethyl-3,4-dihydroxypyrrolidine (DMDP), whereas it excretes related alkaloids from Hyacinthoides non-scripta (Hyacinthaceae). Very few native animals feed on H. non-scripta, but the larvae of E. incanana are specialized herbivores feeding just on the buds and flowers destroying the ovary. DMDP is the major glucosidase inhibitor of H. nonscripta and the moth may overcome inhibition of digestive glucosidases by metabolizing the DMDP. The glucosidase enzymes of the caterpillar are inhibited by DMDP. The caterpillar excretes the other glycosidase inhibitors produced by this plant and the frass has increased concentrations of these alkaloids.
ABSTRACT It has been suggested that systematic upward foraging by pollinators may sometimes help ... more ABSTRACT It has been suggested that systematic upward foraging by pollinators may sometimes help to reduce the geitonogamy: xenogamy ratio on a protandrous raceme with a large daily inflorescence size. This effect will depend on the spatiotemporal distribution of floral gender on the raceme. This paper describes the spatiotemporal patterns of male and female floral gender, in relation to pollinator movement patterns on a raceme, in bluebell, Hyacinthoides non-scripta (Hyacinthaceae), a species in which apical drooping reverses the vertical sequence of flower age on a raceme. Individual flowers began to fade about seven days after bud opening, but remained blue for about 21 days, offering nectar and pollen for most of that time. A typical raceme bore flowers for about 40 days. Flowers were present in the valley woodland population for more than 60 days. Stigmatic receptivity and release of viable pollen began before the corolla was fully open. Experiments indicated that stigmatic receptivity ended soon after the perianth colour began to fade, but that some viable pollen remained available for much longer; and that viable pollen was present in all stages of a flower's life. As the wave of flowering proceeds up a raceme, the flowers at the leading edge exhibit both male and female function. At the trailing (normally lower) edge, male-phase flowers probably extend beyond female-phase flowers. The implications for geitonogamy of the large 'daily inflorescence size' and the reversal of the flower-age/height sequence on the drooping raceme tips are discussed in the context of probable movement patterns of potential pollinators. The terminal flowers on a raceme had smaller gynoecia with fewer ovules than basal flowers, and a lower probability of fruit set, attributed to resource preemption by basal flowers. They probably also had a lower probability of paternity because of the declining proportion of functionally female flowers in the population and perhaps because of reduced pollinator activity due to canopy closure in the wood. Spatiotemporal patterns of male and female reproductive success may vary with site and season in accord with weather-dependent fluctuations in pollinator activity.
Transactions of the Royal Entomological Society of London
ABSTRACT SUMMARY1Species of Passaloecus seal their nests with a sticky material. Mass spectrometr... more ABSTRACT SUMMARY1Species of Passaloecus seal their nests with a sticky material. Mass spectrometric comparisons showed this to resemble a pine resin.2Thin layer chromatography confirmed that the wasp door material was chemically similar to resin found in some conifer species near the nest.3Pine resin is an ideal ‘door material’, and its repellent properties may deter predators.
2-Acylcyclohexane-1,3-diones, a novel class of compounds in the larval mandibular glands ofEphest... more 2-Acylcyclohexane-1,3-diones, a novel class of compounds in the larval mandibular glands ofEphestia(=Anagasta) kuehniella Zeller, act as kairomones. Their relative activities in eliciting oviposition responses from the larval parasiteNemeritis(=Venturia) canescens (Grav.) are reported.
The “fight or flight” syndrome of vertebrates comprises an assemblage of linked responses to arou... more The “fight or flight” syndrome of vertebrates comprises an assemblage of linked responses to arousal or stress, which prepare the body for intense activity. This chapter examines the possibility that arousal involves changes in a wide range of physiological systems and may be manifested over a wide range of intensities and time periods, its effects persisting for hours or days. Thus, the acute fight or flight response would represent an extreme position on an activation continuum, at the other end of which would be less obvious responses of lower intensity that must concern experimentalists because they affect numerous aspects of physiology and behavior. The chapter focuses on the American cockroach, Periplaneta americana. Periplaneta is selected because of its peculiar response to immobilization or stress and the clues that this may give about the effects of insecticides.
A guide to identification, ecology and study of bumblebees. This new edition embraces the wealth ... more A guide to identification, ecology and study of bumblebees. This new edition embraces the wealth of information published on bumblebee life history, ecology, foraging, parasites and conservation in recent years. It includes a new chapter on the very real threats to bumblebees; their crucial role as pollinators of our native flora and crops; ways to promote their survival; advantages and problems posed by their commercial use; as well as updated colour plates, keys and distribution maps of all British species (including Bombus hypnorum). The book introduces techniques and approaches to original work so that anyone with an interest can usefully contribute to furthering our understanding and appreciation of these wonderful and important insects.
Transactions of the Royal Entomological Society of London, 1975
... SARAH A. CORBET* Westfield College (University of London), London NW 3 7ST and ... They appea... more ... SARAH A. CORBET* Westfield College (University of London), London NW 3 7ST and ... They appeared early and seemed to have a flying season of only a few days, whereas females probably lived and flew for about eight weeks after emergence. ...
Field techniques for sampling and measuring the standing crop and secretion rate of nectar are de... more Field techniques for sampling and measuring the standing crop and secretion rate of nectar are described, in order to clarify some discrepancies and omissions in existing reviews of nectar measuring techniques. Slender microcapillary tubes (a fresh one for each sample) are recommended for withdrawing nectar, and a hand held sucrose refractometer, capable of operating with very small fluid volumes, is used for measuring concentration. Potential errors due to the presence of solutes other than sucrose, or to temperatures other than the calibration temperature, are discussed. I consider how measurements of secretion rate are affected by reabsorption and by the nature of the bags used to exclude nectarivores. standing crop / nectar concentration / secretion rate / microcap / refractometer / sucrose / glucose / fructose / amino acids / nectarivore
SummaryPollen grains of oil-seed rape, Brassica napus, were germinated in vitro in conditions in ... more SummaryPollen grains of oil-seed rape, Brassica napus, were germinated in vitro in conditions in which water activity could be closely controlled. Germination success depended on the humidity experienced by the grains before contact with the germination medium, as well as on the osmolarity of that medium. On contact with the germination medium the grains swelled and then shrank. Each suffered one of three fates: it burst, or it germinated without bursting, or it did neither, remaining unchanged. Grains that were to remain unchanged swelled least. Those that were to burst swelled most. Those that were to germinate were intermediate.Some implications for in vitro germination studies are discussed.
Field techniques for sampling and measuring the standing crop and secretion rate of nectar are de... more Field techniques for sampling and measuring the standing crop and secretion rate of nectar are described, in order to clarify some discrepancies and omissions in existing reviews of nectar measuring techniques. Slender microcapillary tubes (a fresh one for each sample) are recommended for withdrawing nectar, and a hand held sucrose refractometer, capable of operating with very small fluid volumes, is used for measuring concentration. Potential errors due to the presence of solutes other than sucrose, or to temperatures other than the calibration temperature, are discussed. I consider how measurements of secretion rate are affected by reabsorption and by the nature of the bags used to exclude nectarivores. standing crop / nectar concentration / secretion rate / microcap / refractometer / sucrose / glucose / fructose / amino acids / nectarivore
Only rarely have bumble bees (Bombus) been observed collecting honeydew from aphids (Aphididae) f... more Only rarely have bumble bees (Bombus) been observed collecting honeydew from aphids (Aphididae) feeding on phloem sap. This behavior may be rare because the percentage of sugar in honeydew egested from aphids is generally well below the sugar concentration in floral nectars preferred by bumble bees. Nonetheless, in August 2018, near St. Buryan, Penzance, Cornwall, UK (56.0602N; -5.6034W) we observed large numbers of wild Bombusterrestris (Linnaeus) collecting honeydew from a colony of the giant willow aphid Tuberolachnussalignus Gmelin feeding on the stems of the willow Salixalba. Unlike aphid-tending ants, who glean fresh honeydew directly from the aphid anal opening, the bumble bees were collecting honeydew from leaf litter below the aphid colony. We hypothesized that honeydew collected from exposed ground surfaces was more concentrated due to evaporation under ambient conditions than that released directly from the anus (fresh honeydew). We thus monitored sugar concentrations of ...
The British moth Eana incanana (Tortricidae) has been found to selectively metabolize the glycosi... more The British moth Eana incanana (Tortricidae) has been found to selectively metabolize the glycosidase inhibitor 2R, 3R, 4R, 5R-2,5-dihydroxymethyl-3,4-dihydroxypyrrolidine (DMDP), whereas it excretes related alkaloids from Hyacinthoides non-scripta (Hyacinthaceae). Very few native animals feed on H. non-scripta, but the larvae of E. incanana are specialized herbivores feeding just on the buds and flowers destroying the ovary. DMDP is the major glucosidase inhibitor of H. nonscripta and the moth may overcome inhibition of digestive glucosidases by metabolizing the DMDP. The glucosidase enzymes of the caterpillar are inhibited by DMDP. The caterpillar excretes the other glycosidase inhibitors produced by this plant and the frass has increased concentrations of these alkaloids.
ABSTRACT It has been suggested that systematic upward foraging by pollinators may sometimes help ... more ABSTRACT It has been suggested that systematic upward foraging by pollinators may sometimes help to reduce the geitonogamy: xenogamy ratio on a protandrous raceme with a large daily inflorescence size. This effect will depend on the spatiotemporal distribution of floral gender on the raceme. This paper describes the spatiotemporal patterns of male and female floral gender, in relation to pollinator movement patterns on a raceme, in bluebell, Hyacinthoides non-scripta (Hyacinthaceae), a species in which apical drooping reverses the vertical sequence of flower age on a raceme. Individual flowers began to fade about seven days after bud opening, but remained blue for about 21 days, offering nectar and pollen for most of that time. A typical raceme bore flowers for about 40 days. Flowers were present in the valley woodland population for more than 60 days. Stigmatic receptivity and release of viable pollen began before the corolla was fully open. Experiments indicated that stigmatic receptivity ended soon after the perianth colour began to fade, but that some viable pollen remained available for much longer; and that viable pollen was present in all stages of a flower's life. As the wave of flowering proceeds up a raceme, the flowers at the leading edge exhibit both male and female function. At the trailing (normally lower) edge, male-phase flowers probably extend beyond female-phase flowers. The implications for geitonogamy of the large 'daily inflorescence size' and the reversal of the flower-age/height sequence on the drooping raceme tips are discussed in the context of probable movement patterns of potential pollinators. The terminal flowers on a raceme had smaller gynoecia with fewer ovules than basal flowers, and a lower probability of fruit set, attributed to resource preemption by basal flowers. They probably also had a lower probability of paternity because of the declining proportion of functionally female flowers in the population and perhaps because of reduced pollinator activity due to canopy closure in the wood. Spatiotemporal patterns of male and female reproductive success may vary with site and season in accord with weather-dependent fluctuations in pollinator activity.
Transactions of the Royal Entomological Society of London
ABSTRACT SUMMARY1Species of Passaloecus seal their nests with a sticky material. Mass spectrometr... more ABSTRACT SUMMARY1Species of Passaloecus seal their nests with a sticky material. Mass spectrometric comparisons showed this to resemble a pine resin.2Thin layer chromatography confirmed that the wasp door material was chemically similar to resin found in some conifer species near the nest.3Pine resin is an ideal ‘door material’, and its repellent properties may deter predators.
2-Acylcyclohexane-1,3-diones, a novel class of compounds in the larval mandibular glands ofEphest... more 2-Acylcyclohexane-1,3-diones, a novel class of compounds in the larval mandibular glands ofEphestia(=Anagasta) kuehniella Zeller, act as kairomones. Their relative activities in eliciting oviposition responses from the larval parasiteNemeritis(=Venturia) canescens (Grav.) are reported.
The “fight or flight” syndrome of vertebrates comprises an assemblage of linked responses to arou... more The “fight or flight” syndrome of vertebrates comprises an assemblage of linked responses to arousal or stress, which prepare the body for intense activity. This chapter examines the possibility that arousal involves changes in a wide range of physiological systems and may be manifested over a wide range of intensities and time periods, its effects persisting for hours or days. Thus, the acute fight or flight response would represent an extreme position on an activation continuum, at the other end of which would be less obvious responses of lower intensity that must concern experimentalists because they affect numerous aspects of physiology and behavior. The chapter focuses on the American cockroach, Periplaneta americana. Periplaneta is selected because of its peculiar response to immobilization or stress and the clues that this may give about the effects of insecticides.
A guide to identification, ecology and study of bumblebees. This new edition embraces the wealth ... more A guide to identification, ecology and study of bumblebees. This new edition embraces the wealth of information published on bumblebee life history, ecology, foraging, parasites and conservation in recent years. It includes a new chapter on the very real threats to bumblebees; their crucial role as pollinators of our native flora and crops; ways to promote their survival; advantages and problems posed by their commercial use; as well as updated colour plates, keys and distribution maps of all British species (including Bombus hypnorum). The book introduces techniques and approaches to original work so that anyone with an interest can usefully contribute to furthering our understanding and appreciation of these wonderful and important insects.
Transactions of the Royal Entomological Society of London, 1975
... SARAH A. CORBET* Westfield College (University of London), London NW 3 7ST and ... They appea... more ... SARAH A. CORBET* Westfield College (University of London), London NW 3 7ST and ... They appeared early and seemed to have a flying season of only a few days, whereas females probably lived and flew for about eight weeks after emergence. ...
Field techniques for sampling and measuring the standing crop and secretion rate of nectar are de... more Field techniques for sampling and measuring the standing crop and secretion rate of nectar are described, in order to clarify some discrepancies and omissions in existing reviews of nectar measuring techniques. Slender microcapillary tubes (a fresh one for each sample) are recommended for withdrawing nectar, and a hand held sucrose refractometer, capable of operating with very small fluid volumes, is used for measuring concentration. Potential errors due to the presence of solutes other than sucrose, or to temperatures other than the calibration temperature, are discussed. I consider how measurements of secretion rate are affected by reabsorption and by the nature of the bags used to exclude nectarivores. standing crop / nectar concentration / secretion rate / microcap / refractometer / sucrose / glucose / fructose / amino acids / nectarivore
SummaryPollen grains of oil-seed rape, Brassica napus, were germinated in vitro in conditions in ... more SummaryPollen grains of oil-seed rape, Brassica napus, were germinated in vitro in conditions in which water activity could be closely controlled. Germination success depended on the humidity experienced by the grains before contact with the germination medium, as well as on the osmolarity of that medium. On contact with the germination medium the grains swelled and then shrank. Each suffered one of three fates: it burst, or it germinated without bursting, or it did neither, remaining unchanged. Grains that were to remain unchanged swelled least. Those that were to burst swelled most. Those that were to germinate were intermediate.Some implications for in vitro germination studies are discussed.
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