Mole Crickets (Scapteriscus spp.) are the most destructive pests in southern turf and pasture grasses. In response to extensive losses from mole crickets, Florida formed a task force to identify natural enemies in the native range of these pests. Two parasitic insects, Larra bicolor and Ormia depleta, and Steinernema scapterisci, an entomopathogenic nematode, were imported and released. Of the two insects, only Larra bicolor has spread to other states infested with mole crickets in the southeast. The present study documents the seasonal biology of Larra bicolor in the northern Gulf region, ornamental plants that can be used as nectar sources, and the impact of these nectar sources on longevity of the wasp and parasitism of mole crickets. Results of field and laboratory experiments showed that the ornamental Pentas lanceolata attracted wasps in the field and provided comparable or better longevity than Spermacoce verticillata which was the only known nectar source.

No description available.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23741号 / 理博第4831号 / 新制||理||1691(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 酒井 章子, 教授 髙林 純示, 教授 松下 智直 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

This diploma thesis entitled "Attractiveness of Planting Species with a Potential to Extend Bee Forage for Bees" discusses pollen and nectar plants planted in the Brník municipality in the Central Bohemian Region. The thesis consists of two parts. The theoretical part describes honeybees, bee plants and their pollen- and nectar production ability as well as bee forage from early spring until late autumn so as to reflect the needs of pollinators as best as possible. The practical part uses pollen analysis to microscopically analyse the representation of pollen grains of plants in the honey produced by local bee colonies. Pollen analyses of honey from own bee colonies are compared with that from bee colonies belonging to neighbouring beekeepers.

The ability to grip on petal surfaces is of crucial importance for the interactions between bees and flowers. In this thesis, I explore the biomechanics of attachment and morphological diversity of bee attachment devices, linking this to the behavioural ecology of bee interactions with flowers. Attachment devices come in two main kinds: claws or spines, and adhesive pads. Claw functioning is poorly described, particularly in terms of how their performance depends on body size, claw geometry, and surface roughness. Claw attachment performance was investigated using several insect species, each covering a large range of body masses. Weight-specific attachment forces decreased with body size, with claw sharpness seemingly playing a role. In bees there is considerable interspecific variation in tarsal claw morphology. This variation, and arolia presence/absence, was categorised for the large bee family Apidae. Cleft/bifid claws were shown to be present in the majority of the Apidae, often with differences between sexes and clades. Using Bombus terrestris, there was no evidence that cleft claws are important for pollen collection; however, I found that the inner tooth of cleft claws can act as a backup if the main tooth breaks. Although this may be one function of cleft claws, there are clearly other unresolved functions well worth further exploration. Investigations were undertaken to explore how petal surface roughness affects bee foraging behaviour. Lab-based foraging trials on B. terrestris visiting artificial flowers varying in slope, surface texture and sugar reward revealed a trade-off between the biomechanical difficulty of visiting and handling the ‘flowers’ and the quality of the reward offered. Flowers that were difficult to grip were often avoided even if they offered a higher reward. To further investigate reward preferences of bees, the effect of sucrose concentration on honey stomach offloading times was also explored. Although the majority of petals do have a rough surface, some have slippery petals. In the field, bumblebees avoided landing on slippery hollyhock petals in favour of the easy-to-grip staminal column. In contrast, honey bees, which are smaller and have larger adhesive pads, landed on both the staminal column and the petals. Slippery petals may be an adaptation to increase contact with plant reproductive structures. Grip is also important to allow the honey bee parasite Varroa destructor to climb on to their host. Attachment forces experiments found that V. destructor could support > 300 times their body mass on honey bees, giving them strong attachment even when bees attempt to remove them through grooming. A grooming-based device for treating V. destructor was tested in an apiary trial. The device was ineffective, providing valuable information for beekeepers considering using this product. In summary, this thesis improves our understanding of the biomechanics of attachment as well as identifying several important aspects of grip in bee-plant interactions.

Plants are under selection to simultaneously attract pollinators while deterring herbivores. This dilemma can lead to tradeoffs in floral traits, which are traditionally thought to be optimized for pollinators. My dissertation addresses the ecological costs and putative functional significance of nectar secondary metabolites, a paradoxical but widespread phenomenon in the angiosperms. I investigate this issue from the pollinator’s perspective using a series of controlled laboratory investigations focused primarily on the bumble bee Bombus impatiens and the nectar alkaloid gelsemine, from Gelsemium sempervirens. I begin by demonstrating that nectar enriched with the alkaloid gelsemine significantly deters visits from bumble bees at a range of natural alkaloid concentrations. However, this aversion can be mitigated by increasing the sucrose concentration such that the alkaloid-rich nectar is more rewarding than its alkaloid-free counterpart. I then demonstrate that the consumption of gelsemine-rich nectar can inhibit oocyte development and protein utilization in bees, but that this effect is limited to bees of suboptimal condition. Continuous consumption of the nectar alkaloid gelsemine also leads to a reduction in the pathogen load of bumble bees infected with Crithidia bombi, but direct interactions between the pathogen and the alkaloid have no impact on infection intensity. Gelsemine also fails to inhibit floral yeast growth, suggesting that nectar alkaloids may not be universally antimicrobial. Finally, I demonstrate that gross nectar cardenolides from the genus Asclepias are strongly correlated with gross leaf cardenolides and that the majority of individual cardenolides found in nectar are a subset of those identified in leaves. This pattern suggests that nectar cardenolides are a consequence of defense for Asclepias; however, they may not be a costly corollary because bumble bees show an overall preference for nectar cardenolides at mean concentrations. Altogether, my dissertation provides a new perspective on the role of chemical defenses against herbivores in plant-pollinator interactions.

Plants are under selection to simultaneously attract pollinators while deterring herbivores. This dilemma can lead to tradeoffs in floral traits, which are traditionally thought to be optimized for pollinators. My dissertation addresses the ecological costs and putative functional significance of nectar secondary metabolites, a paradoxical but widespread phenomenon in the angiosperms. I investigate this issue from the pollinator’s perspective using a series of controlled laboratory investigations focused primarily on the bumble bee Bombus impatiens and the nectar alkaloid gelsemine, from Gelsemium sempervirens. I begin by demonstrating that nectar enriched with the alkaloid gelsemine significantly deters visits from bumble bees at a range of natural alkaloid concentrations. However, this aversion can be mitigated by increasing the sucrose concentration such that the alkaloid-rich nectar is more rewarding than its alkaloid-free counterpart. I then demonstrate that the consumption of gelsemine-rich nectar can inhibit oocyte development and protein utilization in bees, but that this effect is limited to bees of suboptimal condition. Continuous consumption of the nectar alkaloid gelsemine also leads to a reduction in the pathogen load of bumble bees infected with Crithidia bombi, but direct interactions between the pathogen and the alkaloid have no impact on infection intensity. Gelsemine also fails to inhibit floral yeast growth, suggesting that nectar alkaloids may not be universally antimicrobial. Finally, I demonstrate that gross nectar cardenolides from the genus Asclepias are strongly correlated with gross leaf cardenolides and that the majority of individual cardenolides found in nectar are a subset of those identified in leaves. This pattern suggests that nectar cardenolides are a consequence of defense for Asclepias; however, they may not be a costly corollary because bumble bees show an overall preference for nectar cardenolides at mean concentrations. Altogether, my dissertation provides a new perspective on the role of chemical defenses against herbivores in plant-pollinator interactions.

The goals of this research project were to investigate aspects of pollination biology of two native boreal species: Vaccinium myrtilloides (Canadian blueberry) and Vaccinium vitis-idaea (lingonberry) in central Saskatchewan. Accordingly, surveys of insect taxa visiting the flowers were performed, and determination of the effectiveness of these insect taxa to serve as pollinators was measured through pollen deposition and pollen tube growth in the style. Accompanying fieldwork, and morphological and anatomical studies were done for the two food rewards offered by flowers of both Vaccinium species: pollen released through poricidal anthers and nectar secreted from the nectary atop the inferior ovary. Pollen-ovule (P/O) ratios were determined for the two study species in Saskatchewan (V. myrtilloides, V. vitis-idaea) as well as for five other Vaccinium species from eastern Canada (Nova Scotia – V. angustifolium, V. boreale, V. caespitosum, V. corymbosum, and V. uliginosum). Pollen, released at maturity as tetrads, were converted to total pollen grains per flower to yield P/O ratios ranging from 238 (V. caespitosum) to 2,008 (V. vitis-idaea), but 736 for the latter in Saskatchewan. These P/O ratios are indicative of a breeding system ranging from facultative autogamy to facultative xenogamy. Additionally, the structure of mature stamens and pollen tetrads was studied in V. myrtilloides and V. vitis-idaea. Each anther was functionally bilocular; had a single-cell thickness (i.e., epidermis) with regularly occurring papillae; lacked an endothecium; and possessed two distal, hollow tubules each terminating in a pore. Overall pollen grain viability was 76-97% (V. myrtilloides) and 51-93% (V. vitis-idaea), with about 20% of tetrads having only 1-3 grains viable, and 12% and 27% of tetrads entirely non-viable in V. myrtilloides and V. vitis-idaea, respectively. Pollen tetrads occasionally were connected by a sticky substance resembling pollenkitt, but viscin threads were absent. One instance of precocious (in situ) germination of tetrads was recorded within anthers of V. myrtilloides. The floral nectary was a disk of secretory tissue situated between the stamens and the style. The epidermis possessed solitary stomata that were variable in number, but not different between V. myrtilloides and V. vitis-idaea. The nectary was vascularized by phloem alone; many traces were found for V. myrtilloides throughout the nectary, whereas V. vitis-idaea had few traces at the nectary base, concentrated at the inner side of the disk closest to the style base. Young sclerenchyma cells were found throughout the nectary parenchyma. Nectar production started on the day of anthesis for both species, although many flowers of V. vitis-idaea appeared to have no measureable nectar at that time. V. myrtilloides produced a larger range of nectar solutes per flower (0 - 3684.1 μg), than V. vitis-idaea iii (1.29 to 1147.62 μg) over both years; nectar volumes per flower never exceeded 5 μL. Nectar was measured daily in flowers aged 1 – 4 days in 2010 and 1 – 6 days in 2011, however, over the two years at the same study site there was no clear pattern of secretion and reabsorption throughout flower life for V. myrtilloides, and only a gradual increase for V. vitis-idaea as flowers aged. Insect visitors to flowers surveyed in 2010 included a large proportion of honeybees (Apis mellifera) as visitors to both species, whereas in 2011 there were no honeybees present at the field site. There was a larger proportion of hoverflies (Syrphidae) found on the flowers of V. vitis-idaea than on V. myrtilloides. Other visitors to V. myrtilloides were bees (Bombus, Andrena, Osmia, Colletes) and wasps (Vespidae), whereas flowers of V. vitis-idaea were visited by bees (Bombus, Andrena, Osmia, Lasioglossum, Colletes, Hylaeus), an ant (Formicidae) and a butterfly (Lycaenidae). Bombus spp. were shown to be pollinators of V. myrtilloides. Andrena spp. were probable pollinators, whereas honeybees appeared to be poor pollinators. Bombus spp. seemed probable pollinators of V. vitis-idaea and hoverflies to be barely more than visitors, though small sample sizes did not allow for conclusive evidence. The time that an insect spent on a virgin flower had no relationship to the pollination result. Among individuals of various Bombus spp. that did or did not sonicate flowers of V. myrtilloides, the action of “buzz pollination” was shown to result in an increase in the number of pollen tetrads deposited and in pollen tube growth.

Pollination data is provided for a third of the Plectranthus species in southern Africa. In the largest genus of Lamiaceae in the region (53 species), 18 were studied, plus two species of allied genera (Pycnostachys urticifolia and Aeollanthus parvifolius). Study of these 20 species aimed to describe the groups of pollinators that have driven pollinator specialisation. Case histories are provided upon which future studies of Lamiaceae pollination, breeding systems and speciation may be based. Bees (Apidae) and flies (Nemestrinidae, Acroceridae and Tabanidae) are the main pollinating insect groups. Seven straight-tubed Plectranthus species show a match between corolla tube- and proboscis length of nectar-feeding pollinators. Long-proboscid nemestrinid flies are specialised on long-tubed Plectranthus species (P. ambiguus, P. hilliardiae, P. reflexus and P. saccatus), while shorter-proboscid flies of all three families are important pollinators of straight-tubed species with medium- and short corolla tubes. Seven species with sigmoid corolla tubes are bee-pollinated, with fly-pollination prevalent in some. Bent corolla tubes, coupled with length, act as barriers to illegitimate nectarfeeders and ensures alignment of pollinators for effective pollen placement and carryover. It is suggested that straight-tubed species may have evolved from sigmoid-tubed species. Long-tubed species with straight corollas in other Lamiaceae may show convergent pollination by long-proboscid flies, with the guild being dependent on habitat and distribution of plants and flies. Formal establishment of the Stenobasipteron wiedemanni pollination guild extends the study from Plectranthus to selected Acanthaceae, Orchidaceae, Balsaminaceae, Gesneriaceae and Iridaceae, occurring in forested habitat along the Eastern seaboard. Micro-distillation of essential oils confirmed parentage of a putative natural hybrid; once established, hybrid data allows studies of the importance of natural hybridisation events in explaining pollinator fidelity. Nectar sugar studies in Plectranthus mostly showed sucrose dominance; cases of hexose dominance are noted and discussed. Nectar volume and concentration proved variable and do not fit any trends. Pollination by medium-proboscid acrocerid flies has importance for ‘medium-tubed’ plants, since six of the Plectranthus species are solely or partially reliant on Acroceridae for pollination. An appendix with consolidated data describes the 20 study species i.t.o. morphology, habitat, study sites, field work, pollinator observations and insect vouchers. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

Our understanding of bird pollination systems has changed dramatically in the last few years. A long-standing paradigm was that hummingbirds and passerine birds select for different nectar properties in flowers (phylogenetic hypothesis). However, specialist passerines, such as sunbirds, have similar nectar preferences to hummingbirds and nectar in plants pollinated by these two bird groups is strongly convergent. Thus, as an alternative to the existing paradigm, it has been argued that the most useful distinction that can be drawn is that between specialist and generalist avian nectarivores (feeding niche hypothesis). This was supported by phylogenetically-controlled analyses that show that nectar in plants pollinated by specialist avian nectarivores (whether hummingbird or passerine) tends to have a lower volume, higher concentration and higher sucrose content than that in plants pollinated by generalist avian nectarivores. The aim of this thesis was to determine if these trends can be explained by the nectar preferences of avian nectarivores, and to determine whether the generalist-specialist dichotomy can be applied to Kniphofia, a largely bird-pollinated African plant genus. This thesis consists of two sections. In the first, I present data from equicaloric choice experiments to determine sugar preferences of both specialist and occasional nectar feeding birds across a range of concentrations. In addition, I determine apparent sugar assimilation efficiencies and concentration preferences for a range of occasional nectar feeding birds. Using Malachite Sunbirds (Nectarinia famosa), Dark-capped bulbuls (Pycnonotus tricolor), Speckled Mousebirds (Colius striatus) and Red-winged Starlings (Onychognathus morio) (plus Village Weavers (Ploceus cucullatus) in an appendix) as representatives of the major groups of nectar feeding birds in South Africa, I show that some differences occur between occasional nectar feeding birds and all specialist nectar feeding birds studied so far. Specialists show a switch from hexose preference at low (5%) concentrations, exhibit no preference at medium concentrations (10-20%) and prefer sucrose or show no preference at high concentrations (25%). However, specialists are unable to maintain energy balance at low concentrations, and always select the higher concentration when given choices within this range. Occasional nectar feeding birds prefer hexose solutions at low and medium concentrations (5 and 10%), but show varied preferences at higher concentrations. Occasional nectar feeding birds are able to maintain energy balance at low concentrations, and either show no concentration preference, or a preference for lower concentrations when given a choice. Occasional nectar feeding birds show a range in ability to digest sucrose, although some species, like the Dark-capped Bulbul, are quite proficient at it. Surprisingly, no significant difference is found between specialist and occasional nectarivores sugar preferences when analysed globally, even when phyllogeny is accounted for. Instead, I found a significant relationship between body size and bird sugar preference at different concentrations, from which I build the body size hypothesis, which I suggest is a better predictor to use than bird diet type (specialist or occasional nectarivores – feeding niche hypothesis). In the second section of the thesis, I examine the associations between plant traits and nectarivore nectar preferences. This section focuses on flower morphology and nectar characteristics in Kniphofia species, and ecotypes within species, pollinated by specialist versus occasional avian nectarivores. I show that apart from sugar type, which appears to be phylogenetically constrained, flower morphology and nectar characteristics appear to diverge according to whether plants are pollinated by generalist or specialist nectar feeding birds. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.