Pollination biology of the Proteaceae in Australia and southern Africa

Proteaceae are most diverse in southern Africa and Australia, especially in the south-western portions of these regions. Most genera have some species in flower at all times of the year, although generally there is a preponderance of species that flower between late winter and early summer. The one genus that is an exception to this generalization is Banksia, which either has approximately the same percentage of species in flower at various times of the year (southwestern Australia) or peaks in autumn (southeastern Australia). Within particular communities, opportunities for hybridization among congeneric species are minimized by staggered flowering times, different pollen vectors and/or various incompatibility mechanisms. Birds, mammals and arthropods have been identified as visitors to the inflorescences of many Proteaceae. The most common avian visitors to the majority of genera in Australia are honeyeaters, although lorikeets, silvereyes and approximately 40 other species sometimes may be important. Sugarbirds and sunbirds are seen most frequently at inflorescences of Protea, Leucospermum and Mimetes in southern Africa, although they rarely visit other genera. In most cases, avian visitors forage in a manner that permits the acquisition and transfer of pollen. Limited evidence supports the hypothesis that birds are selective in their choice of inflorescences, responding to morphological and/or colour changes and usually visiting those inflorescences that offer the greatest nectar rewards. Arthropods may be equally selective, although it is possible that only the larger moths, bees and beetles are important pollinators, even for those plant species that rely entirely on arthropods for pollen transfer. Mammals are pollen vectors for some Proteaceae, especially those that have geoflorous and/or cryptic inflorescences. In Australia, small marsupials may be the most important mammalian pollinators, although rodents fill this niche in at least some southern African habitats. All but two genera of Proteaceae are hermaphroditic and protandrous, the exceptions being the dioecious southern African genera Aulax and Leucadendron. For hermaphroditic species, the timing of visits by animals to inflorescences is such that they not only acquire pollen from freshly opened flowers but also brush against pollen presenters and stigmas of others that have lost self-pollen and become receptive. Birds and insects (and probably mammals) generally forage in such a way as to facilitate both outcrossing and selfing. Some species are self-compatible, although many require outcrossing if viable seed is to be formed. Regardless of which animals are the major pollen vectors, fruit set is low relative to the number of flowers available, especially in Australian habitats. Functional andromonoecy of the majority of flowers is advanced as the major cause of poor fruit set. The pollination biology and breeding systems of Australian and southern African Proteaceae resemble one another in many ways, partly because of their common ancestry, but also due to convergence. Divergence is less obvious, apart from the dichotomy between dioecious and hermaphroditic genera, and differences in the levels of seed set for Australian and African species. Future studies should concentrate on identifying the most important pollinators for various Proteaceae, the manner in which their visits are integrated with floral development and factors responsible for limiting fruit set.     

The Use of Polyvalent Sera for the Serotyping of Mycobacteria within the Mycobacterium avium– M. intracellulare-M. scrofulaceum Complex

A modification to Schaefer's agglutination method for serotyping mycobacteria within the Mycobacterium avium-M. intracellulare-M. scrofulaceum complex is described. The antigens are screened against polyvalent sera and subsequently a reduced range of absorbed antisera. This expedites the serotyping procedure and conserves expensive antiserum stocks.     

Use of the polymerase chain reaction to identify mosquito species of the Anopheles gambiae complex

A nonradiometric method has been developed for distinguishing between the sibling species Anopheles gambiae Giles and An. arabiensis Patton, two important Afrotropical vectors of malaria. DNA fragments of species diagnostic length are amplified by polymerase chain reaction (PCR) from a small amount of unknown DNA and three different PCR primers. All three PCR primers are based on ribosomal DNA (rDNA) sequences. A universal plus-strand primer (A0) is derived from a conserved region at the 3' end of the 28S rDNA coding region. Two species-specific minus-strand primers (Aa0.5 and Ag1.3) are derived from sequences in the intergenic spacers. The Ag1.3 sequence is approximately 1.3 kb downstream of A0; the Aa0.5 sequence is about 0.5 kb downstream of A0. When mosquito DNA is amplified in the presence of all three primers, a 1.3 kb fragment is produced if An. gambiae DNA is used as template, and a 0.5 kb fragment is produced if An. arabiensis DNA is used. Amplification of DNA from An.gambiae/An. arabiensis hybrids produces both the 1.3 kb and the 0.5 kb fragments. Neither diagnostic fragment is produced when DNA from other species in the An. gambiae complex is used as template.     

Flower colour change in Banksia ilicifolia: A signal for pollinators

Both birds and insects visit yellow flower heads of Banksia ilicifolia rather than those in the pink or red phases. Birds carry most pollen. Substantial nectar and pollen rewards are present only in the yellow phase. The timing of flower colour change also corresponds to a decline in viability of presented pollen and stigma receptivity. Colour change is age-dependent rather than pollinator-induced. Bird visits to yellow or red heads are essentially determined by the availability of nectar in each rather than differences in their visibility. Fruit set is negligible in the absence of pollinators but still < 1% in their presence. Banksia ilicifolia has the smallest heads and is the most localized of five co-occurring and partly co-flowering Banksia species. It is hypothesized that the restriction of flower colour change to B. ilicifolia increases the competitiveness of this species: bird visitors are directed to flower heads with abundant nectar, viable pollen and receptive stigmas, foraging and pollination efficiency thereby being enhanced without a marked reduction in long-distance attractiveness of the tree to potential pollinators.     

Consequences of differences in body mass,wing length and leg morphology for nectar-feeding birds

Nectar-feeding birds are prominent in many parts of the world, and vary with respect to body size. Despite the availability of considerable morphometric data, few concerted efforts have been made to assess the influence of attributes such as mass, wing length and leg morphology upon the speed, acceleration, mode and energetic cost of movement by birds between flowers when foraging for nectar. This review attempts to consolidate and interpret available data and highlight areas where further investigations appear warranted. Australian honeyeaters are generally larger, and American hummingbirds smaller, than Hawaiian honeycreepers and sunbirds of Africa or Asia. Sunbirds, honeyeaters and honeycreepers generally perch while extracting nectar from flowers. Hummingbirds usually hover, apparently because suitable perches close to flowers are lacking, and not because hovering increases the speed at which flowers can be visited. Honeyeaters move from one flower to another at speeds that are at least as great as those for hummingbirds. Most passerine nectarivores need to ingest more nectar per day than hummingbirds in order to maintain energy balance, some species devoting more than 60% of the day to foraging. The major consequence of reduced foraging activity by hummingbirds, which spend only 5–30% of the day in this manner, appears to be male emancipation from nest construction and care of offspring. Large nectarivores have a greater capacity to store surplus food and to fast than smaller birds, and so can take advantage of short-lived peaks in nectar abundance. Nectarivores such as honeyeaters should therefore be favoured by the rapid diurnal changes in nectar availability which are characteristic of many Australian and African habitats. Body mass also determines the likely access to rich sources of nectar through size-related interspecific dominance hierarchies. In all families, larger species tend to monopolize the most rewarding nectar supplies, forcing smaller subordinate species to use poorer, more scattered sources. Within particular species, males usually have longer wings and greater masses than females. These variations imply that the two sexes differ with regard to their foraging ecology, although few supporting data are currently available.     

Comparative effects of Steinernema feltiae (Nematoda: Steinernematidae) and insecticides on yield and cropping of the mushroom Agaricus bisporus

In a mushroom crop (Agaricus bisporus) affected by a very low level of sciarid fly (Lycoriella auripila) infestation, the effects of an indigenous isolate of insect-parasitic nematode (Steinernema feltiae) and of two commonly used insecticides (diazinon and diflubenzuron) were studied. When compared with untreated plots, nematodes applied to the casing had no adverse effects on mushroom yields whereas insecticides decreased yields. At a rate of 3 × 10⁶ infective juveniles per tray (surface area = 0.56 m²), S. feltiae elicited increases of 28.5% and 19% in the mean total numbers and weights of mushrooms respectively. Treatment only with diflubenzuron resulted in 14.6% and 6% reductions in mean total numbers and weights of mushrooms, respectively; treatment with both diazinon and diflubenzuron caused 18.5% and 9.4% losses. Application of nematodes generally reduced the mean weight per mushroom whereas insecticides increased it; nematodes delayed the onset of mushroom production (first flush) whereas diflubenzuron delayed the third and fourth flushes. Nematode contamination of sporophores was minimal when S. feltiae was applied at casing. Although their numbers declined with time, the nematodes persisted, in the casing layer, throughout the cropping period of seven weeks. It is concluded that yield benefits associated with nematode application can result mainly from nematode effects on A. bisporus and not solely from suppression of a damaging pest population.     

Seasonal and diurnal variations in the energetics and foraging activities of the brown honey eater,Lichmera indistincta

In general, the brown honeyeater, Lichmera indistincta, flies more and expends more energy when visiting flowers in the early morning than at other times. Floral nectar is most abundant early in the day, and nectar energy intake by L. indistincta is greatest at that time. It appears as if birds can only store excess energy during the early part of the day, incurring energy deficits at other times. Unit perching and flight costs are greatest for L. indistincta in winter and spring. As a result, peak total energy expenditures and requirements occur at these times, birds apparently being unable to reduce energy demands by employing nocturnal torpor. Estimates of probable energy uptake by L. indistincta from the plant species studied exceed predicted requirements in all seasons except winter, when it is apparent that birds would need to be especially selective in the plants that they used as major energy sources.     

The importance of pre-thicket conifer plantations for nesting Hen Harriers Circus cyaneus in Ireland

Hen Harriers Circus cyaneus are threatened across much of their range and their conservation requires appropriate habitat management. The locations of 148 Hen Harrier nests found in the Republic of Ireland during national breeding surveys in 2000 and 2005 were used to assess nest-site selection. The distribution of these nests was compared to distributions of randomly located points to investigate selection at the scale of the nest-site and landscape. The main nesting habitats selected were pre-thicket stage of first and, particularly, second rotation plantations, mostly of exotic conifers. There was no evidence that the area of post-closure plantations negatively affected Hen Harrier nest distribution. There was a positive correlation across study areas between changes in numbers of Hen Harrier nests between 2000 and 2005 and changes in the area of pre-thicket second rotation plantations over the same period. The overall effect of plantation forests on breeding Hen Harriers in Ireland therefore appears to be positive. However, this study did not consider the effects of plantation habitats on breeding success. Improved grassland was strongly avoided as a nesting habitat. Furthermore, after controlling for the influence of nesting habitat on nest location, landscapes with a high percentage cover of improved grassland were also avoided. Further agricultural intensification of grassland in areas where Hen Harriers breed is likely to have a negative impact on this species. These results are required for the development of management strategies for the conservation of this species.