A perspective on management of Helicoverpa armigera: transgenic Bt cotton,IPM, and landscapes

Helicoverpa armigera is a major pest of agriculture, horticulture and floriculture throughout the Old World and recently invaded parts of the New World. We overview of the evolution in thinking about the application of area‐wide approaches to assist with its control by the Australian Cotton Industry to highlight important lessons and future challenges to achieving the same in the New World. An over‐reliance of broad‐spectrum insecticides led to Helicoverpa spp. in Australian cotton rapidly became resistant to DDT, synthetic pyrethroids, organophosphates, carbamates and endosulfan. Voluntary strategies were developed to slow the development of insecticide resistance, which included rotating chemistries and basing spray decisions on thresholds. Despite adoption of these practices, insecticide resistance continued to develop until the introduction of genetically modified cotton provided a platform for augmenting Integrated Pest Management in the Australian cotton industry. Compliance with mandatory resistance management plans for Bt cotton necessitated a shift from pest control at the level of individual fields or farms towards a coordinated area‐wide landscape approach. Our take‐home message for control of H. armigera is that resistance management is essential in genetically modified crops and must be season long and area‐wide to be effective. © 2016 Society of Chemical Industry     

Long-term impacts of an organophosphate-based regime of pesticides on field and field-edge Collembola communities

During a 6-year study, effects of two contrasting regimes of pesticide use on pitfall and suction catches of Collembola were monitored in an arable field under a rotation of grass and winter wheat. Current farm practice (CFP) represented conventional fungicide and herbicide use plus applications of organophosphorus (OP) insecticides, whereas reduced input approach (RIA) utilised minimum inputs of fungicides and herbicides and excluded any use of insecticides. Compared with RIA, the CFP regime caused a substantial decline in the abundance and diversity of Collembola in the field, including the local disappearance of one species, without recovery during the study. At the field edge, which was protected during OP applications by a 6-m unsprayed buffer zone, effects of the CFP regime were less severe, and were not persistent in the long term. Some Collembola species occurred only in field-edge samples. Pitfall and suction sampling yielded remarkably similar patterns of catches, indicating that pitfall trapping may be appropriate for detecting long-term changes in collembolan abundance caused by intensive agricultural management practices.     

Effects of area and isolation of woodland patches on herbaceous plant species richness across Great Britain

Richness of Ancient Woodland Indicator plant species was analysed in 308 woodland patches that were surveyed during the Countryside Survey of Great Britain carried out in 1998. The Countryside Survey recorded vegetation plots and landscape structure in 569 stratified 1 km sample squares and developed a remotely-sensed land cover map of the UK. Using these datasets, we tested the hypothesis that Ancient Woodland Indicator species richness in woodland fragments was limited by patch area, shape and spatial isolation and that woodland patches located in the lowland region of Great Britain would respond differently than those in the upland region. The variation in Ancient Woodland Indicator species richness in the British lowlands (n = 218) was mainly explained by patch area and two measures of connectivity, the length of hedgerows and lines of trees in the 1 km square and the area of woodland within 500 m of the vegetation plot. By contrast, variation in Ancient Woodland Indicator species richness in the British uplands (n = 90) was related to Ellenberg scores of the vegetation communities sampled – a surrogate for habitat quality – and no significant effect of spatial structure was detected. It therefore appears that the degree of fragmentation of woodland in the British lowlands limits the distribution of Ancient Woodland Indicator species, while in the uplands, failed colonisation is a matter of habitat quality rather than a result of landscape structure.This revised version was published online in May 2005 with corrections to the Cover Date.     

Application and field validation of a PCR assay for the detection of Mycoplasma hyopneumoniae from swine lung tissue samples.

A PCR assay was validated for the detection of Mycoplasma hyopneumoniae in porcine lung tissue. The detection limit of the assay was 0.18 colony-forming units/g of lung sample spiked with M. hyopneumoniae. In field validation, 426 pigs from 220 cases were examined for M. hyopneumoniae infection by M. hyopneumoniae PCR and a fluorescent antibody (FA) test. In total, 103 pig lungs (24.2%) were positive in the PCR test, and 69 pig lungs (16.2%) were positive in the FA test, among which, 62 pigs were positive for both PCR and FA test. Most of the PCR-positive but FA test-negative cases had lesions compatible with M. hyopneumoniae infection. With Bayesian modeling, the diagnostic sensitivity and specificity of the PCR were determined to be 97.3% and 93.0%, respectively.     

Effects of cage netting colour and density on the skin pigmentation and stress response of Australian snapper Pagrus auratus (Bloch & Schneider, 1801)

The unnaturally dark pigmentation of cultured Australian snapper Pagrus auratus can be improved through dietary astaxanthin supplementation and by holding fish in tanks with a white background. The practical application of these laboratory‐based findings was examined with two experiments to establish if the advantages of transferring fish to light coloured tanks before harvest could be achieved on‐farm using white cages and to determine the effects of fish density on skin colour. For the first experiment, snapper (mean TL=29.7 cm) were transferred from a commercial snapper sea cage to black or white netted cages and fed diets supplemented with unesterified astaxanthin (supplied as Lucantin^® Pink, BASF) at 0 or 39 mg kg^?1 for 42 days. Skin colour was measured using the CIE (black–white), (green–red), (blue–yellow) colour scale. Snapper held in white netting cages became significantly lighter (higher ) than snapper held in black cages; however, values were not as high as previous laboratory‐based studies in which snapper were held in white plastic‐lined cages. Snapper fed astaxanthin displayed significantly greater and values, and total carotenoid concentrations after 42 days. In addition, total carotenoids were higher in fish from black than white cages. The second experiment was designed to investigate whether density reduced the improvements in skin colour achieved by holding fish in white coloured cages and whether cage colour affected stress. Snapper (mean weight=435 g) were acclimated to black cages and fed 39 mg kg^?1 astaxanthin for 44 days before transferring to black or white plastic‐lined cages at 14 (low), 29 (mid) or 45 (high) kg m^?3 for 7 days after which time skin colour, plasma cortisol and plasma glucose concentrations were measured. Skin lightness () was greater in snapper transferred to white plastic‐lined cages with the lightest coloured fish obtained from the lowest density after 7 days. Density had no effect on plasma cortisol or glucose levels after 7 days, although plasma cortisol was elevated in snapper from black cages. For improved skin colouration we recommend feeding unesterified astaxanthin at 39 mg kg^?1 for approximately 6 weeks and transferring snapper to white plastic‐lined cages or similar at low densities for short periods before harvest rather than producing fish in white netting sea cages subject to biofouling.     

Effects of dietary astaxanthin concentration and feeding period on the skin pigmentation of Australian snapper Pagrus auratus (Bloch & Schneider, 1801)

A single‐factor experiment was conducted to investigate the effects of dietary astaxanthin concentration on the skin colour of snapper. Snapper (mean weight=129 g) were held in white cages and fed one of seven dietary levels of unesterified astaxanthin (0, 13, 26, 39, 52, 65 or 78 mg astaxanthin kg^?1) for 63 days. Treatments comprised four replicate cages, each containing five fish. The skin colour of all fish was quantified using the CIE L^*, a^*, b^* colour scale after 21, 42 and 63 days. In addition, total carotenoid concentrations of the skin of two fish cage^?1 were determined after 63 days. Supplementing diets with astaxanthin strongly affected redness (a^*) and yellowness (b^*) values of the skin at all sampling times. After 21 days, the a^* values increased linearly as the dietary astaxanthin concentration was increased before a plateau was attained between 39 and 78 mg kg^?1. The b^* values similarly increased above basal levels in all astaxanthin diets. By 42 days, a^* and b^* values increased in magnitude while a plateau remained between 39 and 78 mg kg^?1. After 63 days, there were no further increases in measured colour values, suggesting that maximum pigmentation was imparted in the skin of snapper fed diets >39 mg kg^?1 after 42 days. Similarly, there were no differences in total carotenoid concentrations of the skin of snapper fed diets >39 mg kg^?1 after 63 days. The plateaus that occurred in a^* and b^* values, while still increasing in magnitude between 21 and 42 days, indicate that the rate of astaxanthin deposition in snapper is limited and astaxanthin in diets containing >39 mg astaxanthin kg^?1 is not efficiently utilized. Astaxanthin retention after 63 days was greatest from the 13 mg kg^?1 diet; however, skin pigmentation was not adequate. An astaxanthin concentration of 39 mg kg^?1 provided the second greatest retention in the skin while obtaining maximum pigmentation. To efficiently maximize skin pigmentation, snapper growers should commence feeding diets containing a minimum of 39 mg unesterified astaxanthin kg^?1 at least 42 days before sale.     

Protein and energy utilization and the requirements for maintenance in juvenile mulloway (<Emphasis Type="Italic">Argyrosomus japonicus</Emphasis>)

This study describes the digestible protein (DP) and digestible energy (DE) utilization in juvenile mulloway, and determined the requirements for maintenance. This was achieved by feeding triplicate groups of fish weighing 40 or 129 g held at two temperatures (20 or 26°C), on a commercial diet (21.4 g DP mJ DE⁻¹) at four different ration levels ranging from 0.25% of its initial body weight to apparent satiation over 8 weeks. Weight gain and protein and energy retention increased linearly with increasing feed intake. However, energy retention efficiency (ERE) and protein retention efficiency (PRE) responses were curvilinear with optimal values, depending on fish size, approaching or occurring at satiated feeding levels. Maximum predicted PRE was affected by body size, but not temperature; PRE values were 0.50 and 0.50 for small mulloway, and 0.41 and 0.43 for large mulloway, at 20 and 26°C respectively. ERE demonstrated a similar response, with values of 0.42 and 0.43 for small, and 0.32 and 0.34 for large mulloway at 20 and 26°C respectively. Utilization efficiencies for growth based on linear regression for DP (0.58) and DE (0.60) were independent of fish size and temperature. The partial utilization efficiencies of DE for protein (k _p) and lipid (k _l) deposition estimated using a factorial multiple regression approach were 0.49 and 0.75 respectively. Maintenance requirements estimated using linear regression were independent of temperature for DP (0.47 g DP kg^−0.7 day⁻¹) while maintenance requirements for DE increased with increasing temperature (44.2–49.6 kJ DE kg^−0.8 day⁻¹). Relative feed intake was greatest for small mulloway fed to satiation at 26°C and this corresponded to a greater increase in growth. Large mulloway fed to satiation ate significantly more at 26°C, but did not perform better than the corresponding satiated group held at 20°C. Mulloway should be fed to satiation to maximize growth potential if diets contain 21.4 g DP mJ DE⁻¹.     

Quantifying the respective and additive effects of nectar plant crop borders and withholding insecticides on biological control of pests in subtropical rice

Conservation biological control avoids the need for mass releases of costly agents and the risks associated with introducing exotic agents by promoting existing natural enemies. This is done by alleviating insecticide-induced mortality and by manipulating the habitat to provide resources such as nectar, but there is a dearth of information on the relative and interactive effects of these two approaches. Here we used a large-scale factorial experiment with plots comprised of entire fields to test the effects of, and interactions between, withholding insecticides and planting borders of sesame (Sesamum indicum) on natural enemies and pests over 2 years. We used yellow sticky traps, sweeping netting and sentinel bait plants to monitor natural enemies and pests in the canopy and basal zones of the rice crop. Numbers of rice planthopper egg parasitoids and lepidopterous egg parasitoids in the rice canopy, as well as planthopper parasitism rates, were significantly greater in plots that were unsprayed and bordered by sesame, and scarcest in sprayed crops without sesame. Spraying of sesame-bordered crops gave parasitoid numbers similar to sprayed crops without sesame. Spiders in the canopy were significantly reduced in numbers by spraying, but there was no main effect of sesame borders. This study demonstrates that withholding insecticides and sowing nectar plant borders each have measurable as well as additive benefits on in-crop densities of ecosystem service providers responsible for predating and parasitising pests but the identity of the natural enemy determines the impact of these management practices.