Assessment of the effects of transgenic Bt cotton Bollgard II on the abundance of nontarget arthropods in Burkina Faso

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Potential of a synthetic aggregation pheromone for integrated pest management of Colorado potato beetle

Abstract

• 1 The relative number of colonizing adult Colorado potato beetles (CPB) Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae) coming to pitfall traps baited with the aggregation pheromone (S)‐3,7‐dimethyl‐2‐oxo‐oct‐6‐ene‐1,3‐diol [(S)‐CPB I] and the use of the pheromone in a trap crop pest management strategy were evaluated in the field for the first time.
• 2 More than five‐fold more adult L. decemlineata were caught in pitfall traps baited with the pheromone compared with controls. However, attraction to the pheromone diminished after 5 days in the field.
• 3 In the trap crop management strategy, more colonizing adults were present in pheromone‐treated rows of potatoes compared with untreated middle rows.
• 4 Significantly fewer L. decemlineata egg masses and larvae were found in potato plots that were bordered by pheromone‐treated rows, or bordered by imidacloprid + pheromone‐treated rows, or rows treated at‐planting with imidacloprid compared with untreated (control) potato plots.
• 5 Densities of L. decemlineata egg masses and larvae and percentage defoliation were significantly lower, and marketable tuber yield significantly higher, in conventional imidacloprid‐treated potatoes compared with all other treatments.
• 6 Although our results demonstrate the potential for use of the aggregation pheromone in the management of L. decemlineata in the field, more research is needed to optimize the release rates of the attractant and incorporate control methods for cohabiting pests.

     

Stump‐harvesting for bioenergy probably has transient impacts on abundance,richness and community structure of beetle assemblages

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The effect of red wood ant abundance on feeding damage by the pine weevil Hylobius abietis

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Effects of neonicotinoid seed treatments on wild bee populations in soybean and corn fields in eastern Ontario

1. Neonicotinoid-coated corn and soybean seeds are a common crop in Canada and the US. A growing body of research is demonstrating that, through various exposure routes, neonicotinoids can impact a suite of nontarget organisms including beneficial insects such as bees. However, to date, only a few studies have examined the effects of neonicotinoids in field settings.
2. We assessed the relationship between agricultural crop soil neonicotinoid levels and wild bee abundance and diversity at 16 agricultural sites representing different soil neonicotinoid levels. We detected clothianidin at 11 sites, thiamethoxam at three sites; imidacloprid was not detected.
3. Hedgerow and crop soils were consistent in terms of where clothianidin was detected; thiamethoxan was not detected in hedgerow soils. Based on model outcomes, fields with higher levels of soil neonicotinoids exhibited significantly lower wild bee abundance and diversity than those with low or no neonicotinoids detected.
4. Crop soil neonicotinoid level, hedgerow floral resource abundance and crop type were consistent predictors of bee abundance across models; only neonicotinoid level and crop type were significant predictors of diversity.
5. Our results are consistent with recent findings in the midwestern US, and underscore the potential risk of soil neonicotinoids to wild bee populations across regions and crop systems.

     

Above- and below-ground assessment of carabid community responses to crop type and tillage

1. Carabid beetles are major predators in agro-ecosystems. The composition of their communities within crop environments governs the pest control services they provide. An understudied aspect is the distribution of predacious carabid larvae in the soil.
2. We used novel subterranean trapping with standard pitfall trapping, within a multi-crop rotation experiment, to assess the responses of above- and below-ground carabid communities to management practices.
3. Crop and trap type significantly affected pooled carabid abundance with an interaction of the two, the highest numbers of carabids were caught in subterranean traps in barley under sown with grass.
4. Trap type accounted for the most variance observed in carabid community composition, followed by crop.
5. Tillage responses were only apparent at the species level for three of the eight species modelled.
6. Responses to crop type varied by species. Most species had higher abundance in under-sown barley, than grass, wheat and barley. Crop differences were greater in the subterranean trap data. For predaceous larvae, standard pitfalls showed lowest abundances in under-sown barley, yet subterranean traps revealed abundances to be highest in this crop.
7. Comprehensive estimation of ecosystem services should incorporate both above- and below-ground community appraisal, to inform appropriate management.

     

Diversity and seasonal phenology of aboveground arthropods in conventional and transgenic maize crops in Central Spain

One of the major concerns regarding the release of Bt maize is its potential negative impact on non-target organisms present in this crop. In this paper, we compare the temporal phenology and community structure of the aboveground arthropods in commercial Bt maize fields in Central Spain with those of conventional maize crops, with or without an insecticide (imidacloprid) seed treatment, over a period of three years. Spiders, harvestmen, centipedes, ground beetles, rove beetles, carrion beetles, click beetles, earwigs and damsel bugs were captured in pitfall traps every year in sufficient number to provide meaningful phenological data. One predator spider and three omnivorous species of ground beetles have been consistently present in the maize fields: Pardosa occidentalis, Poecilus cupreus, Pseudophonus rufipes and Pseudophonus griseus, respectively. Rove beetles were caught to a lesser extent, with three dominant species: Acrotona aterrima, Philonthus varians and Platystethus nitens. The variability in activity–density patterns of the aboveground fauna was mainly influenced by the year, but no detrimental effects could be attributed to Bt maize. The only exception being the changes detected in rove beetles, although these differences were transitory and varied from year to year. No changes in species richness and diversity indices for spiders and ground beetles resulted from treatments. However, imidacloprid-treated maize caused a reduction in species richness of rove beetles, even though the abundance of the main species was not reduced. Our results suggest that Bt maize could be compatible with natural enemies that are common in maize fields in Spain.     

Litter‐dwelling beetles (Insecta: Coleoptera) can survive in clear‐cutting during subsequent soil ploughing

1. A 2‐year study of litter dwelling beetles was conducted in different mature pine stands and clear‐cuts in Lithuania using the litter sifting method. We hypothesized that clear‐cutting and subsequent ploughing would increase species diversity and the abundance of beetles, and also would encourage the immediate appearance of early‐successional beetle species replacing late successional species in the clear‐cuts.
2. We did not confirm a hypothesis regarding increase in the number of species and abundance of beetles in clear‐cuts.
3. Our hypothesis regarding the immediate appearance of early successional species and disappearance of late‐successional species in clear‐cuts was confirmed.
4. We also revealed that subsequent soil ploughing in clear‐cuts did not accelerate this process, which was linked to the possibility of late successional species surviving in the undisturbed spaces between the strips of ploughed soil.
5. The present study shows that late‐successional forest litter‐dwelling coleopteran species of old pine forests have a better chance of survival in a ploughed clear‐cut, at least in northern Europe, than has been reported in other studies.

     

Optimising sampling methods for small mammal communities in Neotropical rainforests

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Species number, species abundance and body length relationships of arboreal beetles in Bornean lowland rain forest trees

ABSTRACT.

• 1 The relationships between number of species, abundance per species, and body length are examined for 859 species of beetles in samples of arthropods collected from ten Bornean lowland forest trees by insecticide fogging. Similar relationships are examined for different feeding guilds of these beetles, and for those beetles from different species of trees.
• 2 The data are used to construct four interrelated graphs, namely species: abundance, species: body length, population abundance: body length and total number of individuals: body length distributions.
• 3 In contrast to a number of previous studies, no consistent linear relationship between population density and body length was found for the Bornean beetles and it is suggested that, as in birds, the added dispersal ability of flight reduces critical population densities necessary for persistence in small species. Previous relationships between body weight and population abundance may also be artefacts of the way in which data were gathered.
• 4 Despite large samples, we failed to locate the mode in plots of the number of species in each abundance category (species: abundance distribution).
• 5 Species: body length and total number of individuals: body length plots were similar to those found in previous studies, although using data for Coleoptera alone may have produced a steeper decline in the total number of individuals as body size increases than is apparent in samples of all arthropods.
• 6 We present the first three-dimensional graph relating numbers of species, body lengths and population abundances. The surface of this three-dimensional relationship is relatively simple.

     

Large scale Agriotes spp. click beetle (Coleoptera: Elateridae) invasion of crop land from field margin reservoirs

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Effects of insecticide-treated and Lepidopteran-active Bt transgenic sweet corn on the abundance and diversity of arthropods

A field study was conducted over 2 yr to determine the effects of transgenic sweet corn containing a gene from the bacterium Bacillus thuringiensis (Bt) on the diversity and abundance of nontarget arthropods. The Bt hybrid (expressing Cry1Ab endotoxin for lepidopteran control) was compared with near-isogenic non-Bt and Bt hybrids treated with a foliar insecticide and with a near-isogenic non-Bt hybrid without insecticides. Plant inspections, sticky cards, and pitfall traps were used to sample a total of 573,672 arthropods, representing 128 taxonomic groups in 95 families and 18 orders. Overall biodiversity and community-level responses were not significantly affected by the transgenic hybrid. The Bt hybrid also had no significant adverse effects on population densities of specific nontarget herbivores, decomposers, and natural enemies enumerated at the family level during the crop cycle. As expected, the insecticide lambda-cyhalothrin had broad negative impacts on the abundance of many nontarget arthropods. One insecticide application in the Bt plots reduced the overall abundance of the natural enemy community by 21-48%. Five applications in the non-Bt plots reduced natural enemy communities by 33-70%. Nontarget communities affected in the insecticide-treated Bt plots exhibited some recovery, but communities exposed to five applications showed no trends toward recovery during the crop cycle. This study clearly showed that the nontarget effects of Bt transgenic sweet corn on natural enemies and other arthropods were minimal and far less than the community-level disruptions caused by lambda-cyhalothrin.     

Influence of native ants on arthropod communities in a vineyard

• 1 Ants can have a range of effects on arthropods in crops, including suppressing herbivores such as caterpillars. However, ants can also increase hemipteran densities while reducing natural enemy numbers. In vineyard ecosystem, the effects of native ants and their interactions with other arthropods are poorly understood.
• 2 An ant‐exclusion experiment was designed to test the impact of native ants on both canopy and ground arthropods concurrently. The potential influence of ants on predation and parasitism of light brown apple moth (LBAM) eggs, a grape pest, was also examined. Adult grapevine scale insects and earwigs under bark were counted after a season of ant‐exclusion.
• 3 Among 23 ground ant species collected, six were found to forage in the canopy, with two Iridomyrmex species being the most commonly encountered.
• 4 There was no difference in the abundance of most arthropod orders and feeding groups between ant‐excluded and control vines, although ground spiders were more abundant under ant‐excluded vines, despite increased ground ant foraging pressure. LBAM egg parasitism and predation were low and probably affected by weather and other arthropods. Ant exclusion did not reduce survival of scale insects, although the distribution and abundance of scale insects were negatively associated with earwigs.
• 5 In conclusion, native ants did not consistently suppress arthropod assemblages, including natural enemies, and they did not promote the survival of scale insects. Interactions among native ant species within a vineyard might minimize their effects on other arthropods, although this needs further study.

     

Stand type is more important than red wood ant abundance for the structure of ground‐dwelling arthropod assemblages in managed boreal forests

• 1 The relationships between red wood ants (Formica rufa group) and other ground‐dwelling arthropods were studied in young managed forests stands in Eastern Finland. The main objectives were: (i) to test the influence of stand type (dominant tree species; age: sapling versus pole stage) and numbers of red wood ants on the occurrence of other ground‐dwelling arthropods and (ii) to study the occurrence of red wood ants versus other arthropods on a distance gradient from ant mounds. We used pitfall traps set in 5–14‐year‐old sapling stands and 30–45‐year‐old pole‐stage stands of Scots pine (Pinus sylvestris L.) and birch (Betula spp.) forests.
• 2 Pitfall trap catches of red wood ants did not vary significantly between the forest stand types, although some groups of other arthropods showed clear responses to stand type (e.g. catches of other Formicinae and Gnaphosidae were higher in sapling stands than in pole‐stage stands). The number of red wood ants clearly explained less of the variation in assemblages of other ground‐dwelling arthropods than the forest stand type.
• 3 Red wood ant numbers decreased significantly with distance from the mounds, but the other ground‐dwelling arthropods were insensitive to this gradient or even showed a preference for proximity to ant mounds and high ant activity.
• 4 The results obtained in the present study suggest that wood ants do not have strong effects on several other ground‐dwelling arthropod groups in young managed forests other than in the immediate vicinity of their mounds.

     

Biology of the Eucalyptus leaf beetle Paropsisterna selmani (Chrysomelidae: Paropsini): a new pest of Eucalyptus species (Myrtaceae) in Ireland

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Colonization of disturbed Scots pine trees by bark‐ and wood‐boring beetles

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Arthropod biodiversity in olive groves under two soil management systems: presence versus absence of herbaceous cover crop

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The biology of the ground beetle Harpalus rufipes in a strawberry field in Northumberland

Harpalus rufipes (Degeer) was studied in a strawberry plot in Northumberland from 1973 to 1978 by pitfall trapping, and in the laboratory. Adults were active from April until November. Overwintered male beetles predominated at the beginning of each season until May, followed by overwintered females in June and July. Newly emerged, mainly female, beetles were active from August onwards. Overwintered females matured during early summer and laid eggs in August with a fecundity of 10–15 eggs/female. In the laboratory about 30% of beetles survived from one breeding season to the next. First- and second-instar larvae were caught in pitfall traps in autumn; in the laboratory they made approximately vertical burrows in which they stored seeds taken from the soil surface. Third-instar larvae fed on these seeds and were not active on the surface. Preferred seeds were those of grasses and Chenopodium album L. Larvae were usually aggregated in the soil at densities of 3–20/m².     

Replanting of first‐cycle oil palm results in a second wave of biodiversity loss

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Monitoring carabid indicators could reveal environmental impacts of genetically modified maize

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