Over 50 species of predatory arthropods have been recorded in Australian cotton fields. The complex of generalist predators in Australian cotton has similarities and differences to those in other countries. It is dominated by coccinelids and other beetle species, bugs, ants and spiders. These predators attack Helicoverpa armigera and H. punctigera, the key pests of Australian cotton but also affect other pests such as mites and aphids and prey species with little economic impact suck as leafhoppers. Helicoverpa spp. are primary pests in Australian cotton. Under most pest management regimes predators do not maintain Helicoverpa numbers below current economic thresholds and predator population densities do not appear to be related to Helicoverpa abundance. In contrast, mites and aphids are usually secondary pests whose abundance is determines in part by the impact of pesticides on their natural enemies. This paper will review the predatory species involved, their abundance and seasonal phenology in cotton other crops and non-crop vegetation and the relatively limited data on their impact on Helicoverpa spp. The prospects for enhancing the role of predators of IPM will be discussed in relation to current trends in Australian cotton pest management.

There is no conclusive evidence that Helicoverpa spp. (Lepidoptera: Noctuidae) in Australia have evolved significant levels of resistance to Bollgard II ® cotton (which expresses two Bt toxin genes, cry1Ac and cry2Ab ). However, there is evidence of surviving larvae on Bollgard II cotton in the field. The distribution and survival of early‐instar Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) larvae were examined on whole Bollgard II and non‐Bt cotton plants in greenhouse bioassays. The expression of Cry toxins in various parts of Bollgard II plants was compared to the survival of larvae in those locations. Only 1% of larvae survived after 6 days on greenhouse‐grown Bollgard II plants compared to 31% on non‐Bt cotton plants. Overall, and across all time intervals, more larvae survived on reproductive parts (squares, flowers, and bolls) than on vegetative parts (leaves, stems, and petioles) on Bollgard II plants. The concentration of Cry1Ac toxin did not differ between plant structures, whereas Cry2Ab toxin differed significantly, but there was no relationship between the level of expression and the location of larvae. This study provides no evidence that lower expression of Cry toxins in the reproductive parts of plants explains the survival of H. armigera larvae on Bollgard II cotton.

The ability to identify areas of pasture that are more likely to support damaging levels of the soil-borne, redheaded cockchafer (Adoryphorus couloni) (Burmeister) (RHC) would allow farmers to target expensive control measures. This study explored soil properties, measured via electromagnetic surveys (EM38), pasture biomass via active optical sensors (CropCircle™) and topography via GPS elevation survey as potential indicators of RHC population density. A combination of these variables was used to produce risk maps with an accuracy of 88 % at predicting likely RHC density-categories on a dairy property in the Gippsland region of Victoria, Australia. This risk mapping protocol could be used to improve sampling programs and direct site-specific pest management.

An integrated active optical, and passive thermal infrared sensing system was deployed on a low-level aircraft (50 m AGL) to record and map the simple ratio (SR) index and canopy temperature of a 230 ha cotton field. The SR map was found to closely resemble that created by a RapidEye satellite image, and the canopy temperature map yielded values consistent with on-ground measurements. The fact that both the SR and temperature measurements were spatially coincident facilitated the rapid and convenient generation of a direct correlation plot between the two parameters. The scatterplot exhibited the typical reflectance index-temperature profile generated by previous workers using complex analytical techniques and satellite imagery. This sensor offers a convenient and viable alternative to other forms of optical and thermal remote sensing for those interested in plant and soil moisture investigations using the 'reflectance index-temperature' space concept.

The fraction of absorbed photosynthetically active radiation (fAPAR) for plant canopies is often inferred from top-of-canopy, spectral reflectance, vegetation indices like the normalized difference vegetation index (NDVI). Such measures are derived using passive optical sensors and solar illumination of the canopy. However both the passive sensor-derived NDVI and the accompanying fAPAR measurements are affected by the solar elevation angle (theta(s)). In many cases the effect of theta(s) on both NDVI and fAPAR measurements is similar and the effect of theta(s) is often cancelled out. The new class of active optical sensors (AOS) that contain their own radiant light sources to produce equivalent measurements of NDVI are not influenced by theta(s) even though the accompanying values of fAPAR, as derived using a passive sensor are. This means the fAPAR-NDVIAOS relationship will invariably be sensitive to theta(s). By way of example, this paper investigates the correlations between the NDVIAOS and fAPAR under conditions of varying solar illumination angle for a tall fescue (Festuca arundinacea) pasture. The NDVIAOS was observed to retain a strong linear correlation with fAPAR (R-2 >= 0.85) but fAPAR was highly sensitive to theta(s). Subsequently, simple models can be utilized to predict the fAPAR-NDVIAOS relationship for any solar elevation angle between 30 and 80 degrees. (C) 2014 Elsevier B.V. All rights reserved.

The uptake of silicon (Si) by plants is known to reinforce plant tissues against invertebrate herbivores, but whether there is also direct antibiosis from ingesting Si remains in question. To investigate for antibiotic effects, Si-bearing minerals, wollastonite (CaSiO3) or olivine (Mg/FeSiO3), were added to artificial diets as finely ground powders (40-50m) before or after acidulation to determine whether Si-reduced larval growth. Newly hatched Helicoverpa armigera (Hubner, 1808) and H.punctigera (Wallengren, 1860) (Lepidoptera: Noctuidae) were placed onto the diets and weighed once the larvae on the control diet had completed feeding (day12 for H.armigera; day 14 for H.punctigera: 25.5 degrees C). Acidulated olivine at rates of 0.4-1.7% Si w/dw (weight Si/dry weight of diet) reduced larval weight of H.armigera by 95-99% compared with control diets. Non-acidulated olivine also appeared to cause a decline in larval weight. Wollastonite at rates of up to 3.3% Si had no significant effect on larval weight whether acidulated or not. A similar effect was observed for H.punctigera. Very few insects survived to emergence on diets containing the higher rates of acidulated olivine. Olivine contains quantities of heavy metals, particularly nickel, cobalt and chromium, which can be toxic to insects. Given the lack of toxicity when Si was included as wollastonite compared with similar quantities as olivine, the heavy metals are implicated as the antibiotic agents. Acidulation increased the toxicity of olivine probably by rendering the metals more biologically active. The results of this bioassay do not support the hypothesis that Si is directly antibiotic to Helicoverpa spp. via ingestion.

Site-specific measurements of the apparent electrical conductivity (ECa) of soil using the EM38 were correlated with near-simultaneous neutron probe readings over periods of moisture extraction by an irrigated cotton crop. Thirty sites were monitored from three ECa zones within a 96-ha field of grey Vertosol soil 30 km west of Moree, New South Wales, Australia. This study differs from previous approaches by reporting the effect on ECa of a wetting front (irrigation) reaching a single ECa measurement point in a field and by using polyethylene neutron probe access tubes so that the EM38 could be operated directly over the same site measured by a neutron probe. We report strong correlations (r = 0.94) between neutron probe counts (CRR) averaged to a depth of 40 or 60 cm and ECa from an EM38 held in the vertical mode 20 cm above the soil surface. All combinations of EM sensor height (0–1.2 m) to neutron probe measurement depth (0.2–1.4 m) returned correlations >0.85. The relationship between CCR and ECa was linear for the purposes of estimating water content over a range of background ECa levels. More critical modelling suggested a slight curve (logarithmic model) fitted best. The range of surface-surveyed ECa from the start of irrigation (refill point) to fully irrigated (full point) was ~27 mS m–1 for this Vertosol, where surface ECa readings typically ranged from 50 to 200 mS m–1. We suggest that the calibration of ECa to CRR might be effected by a two-point measurement of the soil, namely at both upper (field capacity) and lower (wilting point) ECa values, and a site-specific calibration template generated by extending these point measures to whole-field surveys.

Monitoring pasture growth rate is an important component of managing grazing livestock production systems. In this study, we demonstrate that a pasture growth rate (PGR) model, initially designed for NOAA AVHRR normalised difference vegetation index (NDVI) and since adapted to MODIS NDVI, can provide PGR at spatial resolution of ~2 m with an accuracy of ~2 kg DM/ha.day when incorporating in-situ sensor data. A PGR model based on light-use efficiency (LUE) was combined with in-situ measurements from proximal weather (temperature), plant (fraction of absorbed photosynthetically active radiation, fAPAR) and soil (relative moisture) sensors to calculate the growth rate of a tall fescue pasture. Based on an initial estimate of LUEmax for the candidate pasture, followed by a process of iterating LUEmax to reduce prediction errors, the model was capable of estimating PGR with a root mean square error of 1.68 kg/ha.day (R2 = 0.96, P-value ≈ 0). The iterative process proved to be a convenient means of estimating LUE of this pasture (1.59 g DM/MJ APAR) under local conditions. The application of the LUE-PGR approach to developing an in-situ pasture growth rate monitoring system is discussed.

The amount of photosynthetically active radiation (PAR, 0.4–0.7 μm) absorbed by plants for photosynthesis relative to incident radiation is defined as the fraction of absorbed photosynthetically active radiation (fAPAR). This is an important variable in both plant biomass production and plant growth modeling. This study investigates the application of a newly developed, linear irradiance sensor (LightScout Quantum Bar Sensor, LightScout, Spectrum Technologies, Inc. USA), to quantify fAPAR for a demonstrator crop, Triticale (X Triticosecale Wittmack). A protocol was devised for sensor placement to determine reflected PAR components of fAPAR and to determine the optimal time of day and sensor orientation for data collection. Coincident, top of canopy, normalized difference vegetation index (NDVI) measurements were also acquired with a CropCircle™ ACS-210 sensor and measurements correlated with derived fAPAR values. The optimum height of the linear irradiance sensor above soil or plant canopy was found to be 0.4 m while measuring reflected PAR. Measurement of fAPAR was found to be stable when conducted within 1 h of local solar noon in order to avoid significant bidirectional effects resulting from diurnal changes of leaf orientation relative to the vertically-placed sensor. In the row crop studied, averaging fAPAR readings derived from the linear irradiance sensor orientated across and along the plant row provided an R2 = 0.81 correlation with above-canopy NDVI. Across row sensor orientation also gave a similar correlation of R2 = 0.76 allowing the user to reduce sampling time.

Correlating soil moisture content to apparent electrical conductivity (σa), derived from above-ground, electromagnetic induction (EMI) dipole sensors, requires capacitance or neutron probe moisture meters. To this end, plastic or metallic access tubes (ca. 0.5-2 m long, 40-50 mm internal diameter, and 1-2 mm thickness walls) are inserted vertically into the soil to allow the probe to be lowered for moisture readings at a series of soil depths. The impact of these tubes on measurements derived from above-ground EMI sensors, when the sensor is in proximity or adjacent to these buried tubes, in unknown. We report on the impact of widely used aluminum (Al), as well as popular plastic alternatives of polyethylene (PE), polyvinylchloride (PVC) access tubes on the lateral σa profiles of an EM38 EMI meter as it is moved along survey transects that pass beside the access tubes. There was no significant difference observed between the EMI meter readings of the bare soil and the vertical holes created to house the access tubes nor when the plastic access tubes were in place. However, the Al tubes showed a considerable variation in readings once the EM38 meter was within 50 cm of the tube location. A theoretical model, based on a single dipole transmitter and receiver coil, and a thin, cylindrical conducting shell located beneath the earth' s surface confirmed the horizontal eddy currents, traveling around the tube shell to be responsible for the observed deviation in the sensor response when in proximity to the metallic tube.

The redheaded cockchafer (Adoryphorus couloni) (Burmiester) (RHC) is a serious pest of improved pastures in south-eastern Australia and current detection relies on pasture damage becoming visible to the naked eye. Various precision agriculture sensors are able to delineate spatial variability in soil texture and moisture content as well as numerous contributing factors to the photosynthetic 'vigour' of pastures, namely biomass, canopy architecture and species composition. The aim of this paper is to seek to determine whether the same technologies can be used to identify paddock zones prone to RHC infestation. This study investigates the association between data generated by a CropCircle™ (an active optical plant canopy sensor (AOS)), an EM38, (an electromagnetic induction soil sensor), and third instar RHC larvae counts. Results indicate that the red wavelength reflected component of the AOS from the pasture canopies offered the most accurate model of third instar RHC larvae count (residual mean square error = 1.04).

Experiments were conducted in small arenas and on whole plants to explore the effect of cotton aphids, A phis gossypii G lover ( H emiptera: A phididae), as alternative prey on the predation of H elicoverpa armigera H übner ( L epidoptera: N octuidae) larvae by green lacewing larvae, M allada signatus S chneider ( N europtera: C hrysopidae). Transgenic Bt ( B ollgard II ® ) and conventional cotton plants were included to explore potential differences in the predator's performance on these cotton types. In small arenas, the presence of 20 aphids reduced predation on H . armigera larvae by 22% (from 5.5 to 3.3 of 10) by a single lacewing larva over a 24‐h period. The presence of H . armigera reduced predation on aphids by ca. 29% (from 16.8 to 11.0 of 20) over 24 h. On whole plants, the presence of alternative prey had no effect on the number of H . armigera larvae or aphids remaining after 3 days. The presence of H . armigera larvae alone, without the predator, caused a 24% reduction in the numbers of aphids on conventional, but not on Bt cotton plants. The combination of Bt cotton and lacewing larvae caused a 96.6% removal of early‐stage H . armigera larvae, a statistically significant increase over the addition of the proportions (91.6%) removed by each factor measured separately, providing evidence of synergism. These studies suggest that the presence of aphids as alternative prey would not necessarily disrupt the predation by green lacewing on larvae of H . armigera , especially on Bt cotton.

We compared the survival of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) eggs and larvae on Bt and conventional cotton, in the presence or absence of the generalist predator, green lacewing larvae, Mallada signatus, (Schneider) (Neuroptera: Chrysopidae). In small arenas, green lacewings consumed a similar number of H.similar to armigera eggs (ave. 15.8 +/- 1.3 on conventional, 12.6 +/- 1.4 on Bt cotton per predator over 24 h) and larvae (ave. 6.8 +/- 0.7 conventional, 6.5 +/- 0.8 Bt per predator over 24 h) whether on Bt or conventional cotton leaves. Likewise, similar numbers of eggs were consumed by each lacewing larva searching whole plants of either Bt (ave. 15.5 +/- 0.6 of 49 over 24 h) or conventional (ave. 13.6 +/- 1.1 of 49 over 24 h). On conventional plants over 72 h, survival of H.similar to armigera larvae was 72.8% and decreased to 37.7% when lacewings were present, giving a net consumption rate of 35.1% (8.6 prey per predator over 72 h). On Bt cotton plants, 13.6% of the H.similar to armigera larvae survived after 72 h and this decreased to 1.7% when lacewings were present. This combination of mortality factors operated synergistically. Helicoverpa armigera larvae moved to fruiting structures on conventional or Bt cotton but failed to survive in the squares (young flower buds) when the impacts of Bt and lacewings were combined. The removal of first to second instar H.similar to armigera larvae from squares of Bt cotton by predators has the potential to reduce immediate pest damage and, perhaps more importantly, remove potentially Bt-resistant genotypes.

Xubida infusella (Walker) (Lepidoptera: Pyralidae) is potentially a useful biological control agent targeting Eichhornia crassipes (waterhyacinth) in the USA but many regions infested with waterhyacinth are also inhabited by an alternative native host, Pontederia cordata (pickerelweed). Experiments were conducted in Australia to assess the impact of X. infusella on pickerelweed compared to waterhyacinth where both these plants were available and X. infusella had already been released. Overall X. infusella had a greater impact on pickerelweed than on waterhyacinth. More than one larva per plant was required to reduce the total shoot dry weight of waterhyacinth but only one larva per plant reduced the total shoot dry weight of pickerelweed. Insect feeding caused the number of secondary shoots (daughter plants) of pickerelweed to double whereas the number of daughter plants produced by waterhyacinth remained unchanged. We suggest this indicates a considerable impact on pickerelweed rather than effective compensation for insect damage because the shoots produced were very small. Waterhyacinth produced a constant number of daughter plants when fed on by up to three larvae per plant. Higher nitrogen status of both species of host plant increased the rate of larval development and pupal weight of X. infusella. The weight and fecundity of X. infusella reared on pickerelweed were lower than those reared on waterhyacinth but large numbers of progeny were produced on both plant species. This experiment demonstrates a considerable impact of X. infusella on pickerelweed suggesting this plant is at risk from this agent if released in the USA where pickerelweed is present. The considerable impact on waterhyacinth demonstrates the potential for this insect to contribute to waterhyacinth control in countries where risk assessment favours release.

1. Pollen can be transported thousands of kilometres by insects but its viability after long-distance transport is not known. Knowing the potential for this mechanism to cause outcrossing of transgenes from genetically modified (GM) plants is important for risk assessments.2. The viability of pollen from cotton (Gossypium hirsutum L.) and canola (Brassica napus L.) was determined after placing it on the proboscis of Helicoverpa armigera moths for intervals of up to 32 h. Viability of both cotton and canola pollen declined at a much greater rate when in contact with the moth proboscis. Most was non-viable by 8 h compared with 16 h for control cotton pollen or 32 h for canola pollen.3. There was no significant difference in the rate of decline of pollen viability between the five conventional cotton varieties, or between these and the one GM cotton variety used in these experiments.4. The number of canola pollen grains remaining on the proboscis declined over time. Very few cotton pollen grains were retained on the proboscis.5. The reduction in pollen viability during contact with the proboscis might indicate partial ingestion of the pollen via the proboscis.6. The points above suggest that pollen is unlikely to remain attached or remain viable when carried over large distances by H. armigera. The implications for spread of pollen from transgenic plants and for pollination ecology in general are discussed.

This paper is the third in a series designed to demonstrate the application of rigorous, systematic hazard identification techniques to ecological systems. Here we use Hierarchical Holographic Modelling to identify the potential ecological hazards associated with the commercial release of herbicide tolerant oilseed rape. Hierarchical Holographic Models decompose complex systems into a series of sub-systems and consider interactions between the components and processes of these sub-systems in order to identify hazards. In this example we considered 1356 potential interactions between the biological, chemical and physical components and processes of the herbicide tolerant oilseed rape environment, and identified 152 potential hazards, grouped into 14 categories. The hazards were subsequently scored for degree of concern and plausibility, and then compared with an equivalent list of hazards generated independently by a checklist approach. The incidence of herbicide tolerant volunteers (and weeds) both on and off the farm had the highest average score of all the ecological hazard categories. The checklist based approach identified or implied 44% of the hazards identified in the Hierarchical Holographic Model, including nine of the ten hazards ranked most important. The checklist approach focussed almost exclusively on the phenotypic and genotypic hazards associated with herbicide tolerant oilseed rape and largely ignored the hazards associated with the circumstances surrounding its use. As a result the checklist identified only 6 out of the 79 potential hazards associated with changes to farming practice. The commercial release of herbicide tolerant oilseed rape will be associated with changes in tillage and the application of post-emergent herbicides. It may also lead to changes in spray schedules of insecticide and fungicide. Many of the environmental hazards identified with these changes are plausible and may warrant further investigation or targeted monitoring.

MankindVolume 10, Issue 3 p. 151-155 Is There a Place for the Proton Magnetometer in Australian Field Archaeology? GRAHAM CONNAH, GRAHAM CONNAH Department of Prehistory and Archaeology, and Department of Geophysics, University of New England.Search for more papers by this authorPENELOPE EMMERSON, PENELOPE EMMERSON Department of Prehistory and Archaeology, and Department of Geophysics, University of New England.Search for more papers by this authorJOHN STANLEY, JOHN STANLEY Department of Prehistory and Archaeology, and Department of Geophysics, University of New England.Search for more papers by this author GRAHAM CONNAH, GRAHAM CONNAH Department of Prehistory and Archaeology, and Department of Geophysics, University of New England.Search for more papers by this authorPENELOPE EMMERSON, PENELOPE EMMERSON Department of Prehistory and Archaeology, and Department of Geophysics, University of New England.Search for more papers by this authorJOHN STANLEY, JOHN STANLEY Department of Prehistory and Archaeology, and Department of Geophysics, University of New England.Search for more papers by this author First published: June 1976 https://doi.org/10.1111/j.1835-9310.1976.tb01145.xCitations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume10, Issue3June 1976Pages 151-155 RelatedInformation