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1.
Curr Res Insect Sci ; 1: 100011, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-36003607

RESUMO

The establishment success of a population is a function of abiotic and biotic factors and introduction dynamics. Understanding how these factors interact has direct consequences for understanding and managing biological invasions and for applied ecology more generally. Here we use a mesocosm approach to explore how the size of founding populations and the number of introduction events interact with environmental conditions (temperature) to determine the establishment success of laboratory-reared Drosophila melanogaster. We found that temperature played the biggest role in establishment success, eclipsing the role of the other experimental factors when viewed overall. Under optimal temperature conditions propagule pressure was of negligible importance to establishment success.  At adverse temperatures, however, establishment success increased with the total founding population size. This effect was considerably stronger at the cold than at the hot extreme. Whether the population was introduced all at once or by increments (changing the number of introduction events) had a negligible global effect. However, once again, a stronger effect of increasing number of introduction events was seen at adverse temperatures, with hot and cold extremes revealing opposite effects: adding flies incrementally decreased their establishment success at the hot extreme, but increased it at the cold extreme. These differing effects at hot and cold thermal extremes implies that different establishment mechanisms are at play at either extreme. These results suggest that the effort required to prevent (or conversely, to facilitate) the establishment of populations varies with the environment in ways that can be complicated but predictable.

2.
Plant Biol (Stuttg) ; 18(1): 124-31, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25865269

RESUMO

Reproduction is a crucial stage in the naturalisation of introduced plant species. Here, using breeding system experiments and observations of floral visitors, we investigate whether a lack of pollinators or an inability to autonomously self-fertilise limits naturalisation in five Australian Banksia species and the co-familial Hakea salicifolia in South Africa. Banksia species were heavily utilised by native insects and nectar-feeding birds. Although Banksia produced fruit when pollinators were excluded, pollinators significantly increased seed set in four of the five species. H. salicifolia flowers were visited by 11 insect species; honeybees (Apis mellifera) were the main visitors. Flowers in naturalised H. salicifolia populations received almost four times the number of visits as flowers in non-naturalised populations; the latter showed both pollen limitation (PLI 0.40) and partial self-incompatibility. This should not prevent invasion, since H. salicifolia produces fruits via autonomous selfing in the absence of pollinators. The results suggest a limited role of breeding systems in mediating naturalisation of introduced Proteaceae species. Other factors, such as features of the recipient environments, appear to be more important. Spatial variation in rates of reproduction might, however, explain variation in the extent and rate of naturalisation of different populations.


Assuntos
Polinização/fisiologia , Proteaceae/fisiologia , Autofertilização/fisiologia , Animais , Austrália , Abelhas , Flores/fisiologia , Insetos , Espécies Introduzidas , Pólen , Sementes/crescimento & desenvolvimento , África do Sul
3.
Bull Entomol Res ; 96(2): 145-52, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16556335

RESUMO

The release of classical biological control agents has reduced the economic, environmental and social problems caused by water hyacinth, Eichhornia crassipes; however, additional control measures are needed in some locations. Water hyacinth plants were treated with different densities of eggs of the weevil Neochetina eichhorniae Warner, one of the main control agents, under different nutrient regimes in a controlled experiment. Plants were destructively sampled and the development of N. eichhorniae was assessed. The survival of first and second instars declined as larval density increased. Plant nutrient status did not directly affect the mortality rate of larvae, but at higher nutrient concentrations larvae developed faster and were larger at a given developmental stage. It is argued that the density dependence operating in N. eichhorniae occurs through an interaction between young larvae and leaf longevity. Consequently, events which disrupt water hyacinth leaf dynamics, e.g. frost or foliar herbicides, will have a disproportionately large effect on the control agents and may reduce the level of control of the host.


Assuntos
Eichhornia/fisiologia , Controle Biológico de Vetores , Gorgulhos/crescimento & desenvolvimento , Fenômenos Fisiológicos da Nutrição Animal , Animais , Eichhornia/parasitologia , Larva/crescimento & desenvolvimento , Larva/fisiologia , Oviposição/fisiologia , Densidade Demográfica , Pupa/crescimento & desenvolvimento , Análise de Sobrevida , Água/química , Gorgulhos/fisiologia
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