Abundance Of Pest Species Research Articles

The Dominance Hierarchy of Wood-Eating Termites from China.

Competition is a fundamental process in ecology and helps to determine dominance hierarchies. Competition and dominance hierarchies have been little investigated in wood-eating termites, despite the necessary traits of similar resources, and showing spatial and temporal overlap. Competition and dominance between five species of wood-eating termites found in Huangzhou, China, was investigated in three laboratory experiments of aggression and detection, plus a year-long field survey of termite foraging activity. Dominance depended on body size, with largest species winning overwhelmingly in paired contests with equal numbers of individuals, although the advantage was reduced in paired competitions with equal biomass. The termites could detect different species from used filter papers, as larger species searched through paper used by smaller species, and smaller species avoided papers used by larger species. The largest species maintained activity all year, but in low abundance, whereas the second largest species increased activity in summer, and the smallest species increased their activity in winter. The termite species displayed a dominance hierarchy based on fighting ability, with a temporal change in foraging to avoid larger, more dominant species. The low abundance of the largest species, here Macrotermes barneyi, may be a function of human disturbance, which allows subordinate species to increase. Thus, competitive release may explain the increase in abundance of pest species, such as Coptotermes formosanus, in highly modified areas, such as urban systems.

Declines in biodiversity and the abundance of pest species across land use gradients in Southeast Asia

Context Changes in land use have disruptive effects on community structure, causing many species to disappear, though a few thrive and become pests.

Relationship between pest birds and landscape elements in the Pampas of central Argentina

Many species of birds are considered pests in rural areas modified for agricultural production. We evaluated the abundance of four species of avian pests (Eared Dove (Zenaida auriculata), Monk Parakeet (Myiopsitta monachus), Picazuro Pigeon (Patagioenas picazuro) and Spot-winged Pigeon (P. maculosa)) in the Pampas of central Argentina. From 2006 to 2008, we surveyed 35 transects along secondary roads. All four species showed a response to the presence of exotic woodlots in rural areas. Monk Parakeets and the two pigeons were more likely to be found in woodlots with tall, perennial trees (Eucalyptus spp.), whereas Eared Doves were more likely to be found in woodlots with short, perennial trees (mainly species of Pinus and Casuarina). We did not detect any association between abundance of pest species and the presence of crops. These results suggest that management of exotic perennial trees in rural areas of the Pampas of central Argentina may provide a means of control of pest birds.

The implications of predicted climate change for insect pests in the UK, with emphasis on non‐indigenous species

AbstractRecent estimates for global warming predict increases in global mean surface air temperatures (relative to 1990) of between 1 and 3.5 °C, by 2100. The impact of such changes on agricultural systems in mid‐ to high‐latitude regions are predicted to be less severe than in low‐latitude regions, and possibly even beneficial, although the influence of pests and diseases is rarely taken into account. Most studies have concluded that insect pests will generally become more abundant as temperatures increase, through a number of inter‐related processes, including range extensions and phenological changes, as well as increased rates of population development, growth, migration and over‐wintering. A gradual, continuing rise in atmospheric CO2will affect pest species directly (i.e. the CO2fertilization effect) and indirectly (via interactions with other environmental variables). However, individual species responses to elevated CO2vary: consumption rates of insect herbivores generally increase, but this does not necessarily compensate fully for reduced leaf nitrogen. The consequent effects on performance are strongly mediated via the host species. Some recent experiments under elevated CO2have suggested that aphids may become more serious pests, although other studies have discerned no significant effects on sap‐feeding homopterans. However, few, if any of these experiments have fully considered the effects on pest population dynamics. Climate change is also considered from the perspective of changes in the distribution and abundance of species and communities. Marked changes in the distribution of well‐documented species – including Odonata, Orthoptera and Lepidoptera – in north‐western Europe, in response to unusually hot summers, provide useful indications of the potential effects of climate change. Migrant pests are expected to respond more quickly to climate change than plants, and may be able to colonize newly available crops/habitats. Range expansions, and the removal of edge effects, could result in the increased abundance of species presently near the northern limits of their ranges in the UK. However, barriers to range expansions, or shifts, may include biotic (competition, predation, parasitism and disease), as well as abiotic, factors. Climatic phenomena, ecosystem processes and human activities are interactive and interdependent, making long‐term predictions extremely tenuous. Nevertheless, it appears prudent to prepare for the possibility of increases in the diversity and abundance of pest species in the UK, in the context of climate change.