Gordon Purvis

The influence of cropping rotations and soil cultivation practice on the population ecology of carabids (Coleoptera: Carabidae) in arable land

Summary Use is made of detailed information on the lifecycles and phenology of carabid beetles in arable fields to analyse pitfall catches and seek evidence for the hypothesis that pre-adult instars in the soil are susceptible to soil tillage operations at particular times of the year. Strictly autumn-breeding species were trapped less frequently at the time of adult emergence in early summer when soil cultivation was done for crop establishment in late spring compared with uncultivated or autumn-sown fields. Analysis of data for species with distinct reproductive cohorts in autumn and spring produced evidence that the larval over-wintering cohort, but not the adult hibernating cohort, was similarly affected by soil cultivation. No evidence was found to suggest that cultivation at the time of egg or early larval instars directly influences the survival of populations and it is concluded that probably only cultivation-induced mortality of late larval and pupal instars has a significant population effect. The longer-term survival of most carabids in arable fields probably depends on either flexibility in their time of breeding or, for strictly autumn-breeding species, on a well-developed phase of post-emergence dispersal by adult beetles. It is concluded that soil cultivation directly impacts on the incidence of larval over-wintering populations and limits the range of lifecycles and phenologies that are possible in arable land. Such constraints may explain the phenomenon of long-term population robustness that is often exhibited by carabid populations in arable crops when they are subject to non-target pesticide effects.

Successional changes in the arthropod fauna of a new ley pasture established on previously cultivated arable land.

In April, July and November 2002 and April 2003, a quadrat investigation of macrobenthos was conducted at four sampling profiles in the intertidal flat of Yangtze Estuary. The concentrations of Cu, Pb, Fe, Mn, Zn and Cr in several high biomass macrobenthos were determined, their absorbed amounts per square meter were calculated, and the biological quality of Corbicula fluminea and Siliqua minima was evaluated. The results showed that C. fluminea was widespread in the intertidal, especially in the low tidal flat of Yangtze Estuary, and heavy metals were mainly concentrated in its soft tissues. C. fluminea could selectively absorb Cu, leading to the little variation of Cu concentration in the tissues of C. fluminea sampled from different coastal region. Mollusks Rissoina sp. and Bullacta exarata, and all crustaceans could markedly accumulate Cu in their bodies, and the BSAF value reached 2.97-7.97. The mollusks and crustaceans had the greatest absorption of Fe per square meter, followed by Mn, Zn and Cu, and Pb and Cr. The amount of Cu, Pb, Fe and Cr absorbed by B. exarata larva from per square meter intertidal flat was obviously higher than that by other macrobenthos, while the absorbed amount of Mn and Zn in B. exarata larva was less than that in C. flunzinea collected from XuPu. The concentrations of Pb and Cr in the soft tissues of C. fluninea and S. miniema were relatively lower in the intertidal flat of Yangtze Estuary than in other coastal and estuarine areas, and those of Cu and Zn were also low but at appreciable level. Compared to the criterion for marine biological quality in China, the edible soft tissue of Corbicula fluminea and S. minima in the tidal flat of Yangtze Estuary was relatively safe for human beings.(1) Changes in the arthropod fauna of a newly established ley pasture were monitored in soil and vegetation. Soil and foliage communities increased in species richness during the 3-year study. Numbers in the soil to a depth of 5 cm increased in each successive year from 2317 to 114 413 individuals m-2. However, most groups extracted from the foliage by Tullgren funnel showed no significant change in abundance. (2) Various groups collected in suction net samples exhibited contrasting population trends. Insect numbers attained a late summer peak which became greater in successive years. Numbers of Cryptostigmata increased steadily throughout the study. Detritivorous Collembola exhibited population minima in midsummer when phytophagous species attained peak abundance. (3) A graphical method of tracing the accumulation of species in small samples was more useful for quantifying changes in the faunal complexity of the study site than were conventional indices of diversity.

The role of grassland sward islets in the distribution of arthropods in cattle pastures.

1. It is well documented that cattle reduce their grazing activity in the vicinity of cattle dung, which gives rise to distinct patches, or islets as they have been termed, of longer sward. The influence of such islets on pasture utilisation and agronomic performance has been widely studied, but very little information is available concerning their influence on grassland biodiversity.

Development of a Sustainably-Competitive Agriculture

The need for both Competitiveness and Sustainability, the two primary overarching goals of EU policy, present the agri-food sector with a unique set of formidable challenges and uncertainties. These point to the need for development of new, quality-focused models for agriculture and food production that are sustainably-competitive. The design criteria for the concept are outlined and developed within the context of an agronomic model for multifunctional, grass-based cattle production systems. This model highlights the importance of harnessing the benefits of functional biodiversity within two key epicenters of the system in order to realise both agronomic and environmental – and hence economic – advantage. Whilst much of the knowledge needed to implement the described model already exists, the functionality of biologically complex rumen and pasture processes within the two key system epicenters, represent the two main pillars of an innovation-driven research programme that is needed to provide fundamental new knowledge necessary to underpin practical development of the model.

A new ascid mite from St Helena with observations on the Protogamasellus complex (Acari: Mesostigmata)

A new genus, Protogamasellopsis (family Ascidae), is proposed to accommodate the type species Protogamasellopsis corticalis sp. nov and Protogamasellus diocorus Manson. The classification of the Protogamasellus complex is discussed and a new subgenus, Protogamasellodes (type: Protogamasellus hibernicus Evans), is erected. A key is given for the separation of the genera Gamasellodes, Protogamasellus s.lat and Protogamasellopsis.

The influence of conservation field margins in intensively managed grazing land on communities of five arthropod trophic groups

Abstract.  1. Arthropods, a major component of functional biodiversity within agro‐ecosystems, contribute to sustainability through processes including nutrient cycling and pest control. Extensively managed field margins can help protect this functional biodiversity by providing habitat for beneficial species.

An assessment of bird species within Irish agricultural landscapes using the Field Boundary Evaluation and Grading System

Capsule The Field Boundary Evaluation and Grading System (FBEGS) is a useful predictor of bird populations found in field boundaries located in southeast Ireland. Aims To assess the potential of FBEGS to evaluate the ecological quality of field boundaries in agricultural ecosystems and as a tool for the measurement of bird populations within field boundaries. Methods Surveys of bird populations were made in selected field boundaries on 50 farms in southeast Ireland in winter and during the breeding season. FBEGS surveys were also carried out on field boundaries to assess ecological quality. glms were fitted to assess the utility of the FBEGS Index as a predictor of bird populations. Results The FBEGS Index was an effective predictor of bird populations in the breeding season, but had limited use in predicting bird populations in winter. Within the overall FBEGS Index, the Associated Features score was a good predictor for populations in both the winter and breeding seasons. In addition, the Boundary Structural score of the field boundary was also an accurate predictor of birds in the breeding season. Conclusion The FBEGS Index has high potential for predicting the effect that changes in the farmed landscape will have on bird populations.

A comparison of the occurrence of aphids and barley yellow dwarf virus in minimum-till and conventional-till autumn-sown cereals

Winter barley was sown by conventional-tillage (CT) and minimum-tillage (MT) cultivation over three seasons. Each cultivation treatment was split so that straw was incorporated into the soil during cultivation in one split, while the other did not receive straw. Aphid occurrences in autumn and incidence of barley yellow dwarf virus (BYDV) in spring were compared. Similar investigations on winter wheat were made over a further three seasons. The method of cultivation affected the number of aphids on barley and wheat plants in autumn and on wheat heads in summer; MT had fewest aphids. Soil incorporation of straw during cultivation had a similar effect. Method of cultivation affected the incidence of BYDV disease, with MT having least infection. Straw-treated cereal plots had fewer aphids and less BYDV than no-straw plots. Aphids and virus reached damaging levels only in the first barley crop. In this season, MT barley had significantly fewer aphids (48 % fewer) and significantly less BYDV (71 % less) than CT. Straw-treated plots within the CT system had rather similar aphid infestation and BYDV incidence as no-straw plots. Barley grown in the MT system with straw added had significantly fewer aphids (68 %) than in the case when no straw was added. Overall, aphids in autumn were significantly fewer on MT relative to CT cereals in three of the six seasons and significantly fewer on straw relative to no-straw plots in two seasons. Aphids on wheat heads in summer were significantly fewer in MT relative to CT plots in one of the three seasons. Aphids on heads were also significantly fewer on straw-treated plots within each system of cultivation in two seasons, while MT wheat with straw had significantly fewer aphids/head than those without straw in one season. BYDV was lower each season in MT barley and wheat when compared with CT crops. These differences were significant for two of the three seasons in which each crop was grown. There was a lower incidence of virus in straw-treated plots than in no-straw plots. This effect was significant for one of the three seasons in which barley and wheat were grown. Plant and tiller density did not differ significantly between MT and CT barley either with or without straw incorporation. Plant density of wheat in autumn was significantly lower for straw-treated plots relative to no-straw plots in one season. Wheat head density was lower for MT relative to CT in one season, while MT with straw had significantly fewer heads than CT plots with straw in two seasons. BYDV significantly reduced grain yield only in 2001/02 when incidence of the disease was high. Grain yield in 2001/02 was 0·95 t/ha (16%) greater for MT barley, due to less BYDV, than for CT. Straw-treated CT barley outyielded no-straw plots by 0·45 t/ha, while the comparable value for the MT system was 0·3 t/ha. The combined effect of MT plus straw had a 1·24 t/ha (21 %) yield advantage over CT without straw. It is concluded that MT cereals sown at the same time as CT crops in autumn have a lower risk of aphid infestation and BYDV infection than CT crops. The soil incorporation of straw further enhances the beneficial impact of MT in reducing aphids and virus.

Astigmatic mites of the genera Schwiebea Oudms. and nanacarus oudms. from S. E. Ireland

Summary Schwiebea hibernica sp. nov. (Acaridae) and Nanacarus manus sp. nov. (Saproglyphidae) are described and figured. Species relationships within the genus Nanacarus Ouds., are considered and a key is given for the identification of females. Nanacaroides Volgin and Mironov 1979 is synonymized with Nanacarus Oudemans 1903.

The response of sward-dwelling arthropod communities to reduced grassland management intensity in pastures

Abstract We compared arthropod taxon richness, diversity and community structure of two replicated grassland husbandry experiments to investigate effects of reduced management intensity, as measured by nutrient input levels (390, 224 and 0 kg/ha per year N in one experiment, and 225 and 88 kg/ha per year N in another). Suction sampling was used to collect Araneae, Coleoptera, Hemiptera and Hymenoptera, with Araneae and Coleoptera also sampled with pitfall trapping. Univariate analyses found no significant differences in abundance and species density between treatments. However, with multivariate analysis, there were significant differences in arthropod community structure between treatments in both experiments. Reducing N input and associated stocking rates, as targeted by agri-environment schemes, can significantly alter arthropod communities but without increasing the number of species present. Other approaches that may be necessary to achieve substantial enhancement of sward arthropod biodiversity are suggested.