Global disparity in public awareness of the biological control potential of invertebrates

Invertebrates make up over 95% of animal biodiversity on Earth and contribute to multiple ecosystem services (ES) in natural and human-dominated systems. One such service, biological control (BC) of herbivorous pests, is a core component of sustainable intensification of agriculture, yet its importance is routinely overlooked. Here we report a macro-scale, cross-cultural assessment of the public visibility (or 'salience') of BC invertebrates, using high-throughput analysis of large bodies of digitized text (i.e., 'culturomics'). Using binomial scientific name frequency as proxy for visibility, we compared the extent to which a given species featured in webpages within either scientific media or the entire worldwide web, and in total search volume at varying spatial scale. For a set of 339 BC invertebrate species, scientific and internet coverage averaged 1020 and 1735 webpages, respectively. Substantial variability was recorded among BC taxa with Coleoptera, Hemiptera and Nematoda having comparatively high visibility. Online visibility exhibited large geographical variability ranging from France covering BC invertebrates on average in 1050 webpages versus Thailand or Indonesia on just 31-38. This work represents the first extensive use of culturomics to assess public visibility of insect-mediated ES. As BC uptake is dictated by stakeholders' access to (agro-ecological) information, our work identifies geographically-delineated areas that are differentially attuned to the concept of invertebrate BC, pinpoints opportunities for focusing education campaigns and awareness-raising, enables real-time tracking of BC public appeal, and informs public policy.

Silicon enhances natural enemy attraction and biological control through induced plant defences

Silicon (Si) is known to have a role in constitutive plant defence against arthropod pests, and recent work has illustrated involvement in induced plant defences. The present tri-trophic study tested the hypothesis that Si increases natural enemy attraction to pest-infested plants and improves biological control. Cucumber plants treated with potassium silicate (Si+) and untreated control plants (Si-) were maintained in separately vented glasshouse compartments. Y-tube olfactometer studies showed that adult Dicranolaius bellulus were significantly more attracted to Si+ plants upon which Helicoverpa armigera larvae had fed compared with Si-, pest-infested plants. Predators were not significantly more attracted to Si+ plants when comparing uninfested cucumbers. In a field experiment, we placed H. armigera-infested and uninfested Si+ and Si- cucumber plants in a lucerne stand. Removal rates of H. armigera egg baits showed predation was greater for Si+ infested plants than for other treatments. Results suggest that Si applied to plants with a subsequent pest infestation increases the plants' attractiveness to natural enemies; an effect that was reflected in elevated biological control in the field.

First Report of a "Candidatus Phytoplasma australiense"-Related Strain in Lucerne (Medicago sativa) in Australia

Australian lucerne yellows (ALuY), a phytoplasma-associated disease, is a major problem in Australia that causes the pasture seed industry millions of dollars in losses annually (3). Samples were collected from lucerne (Medicago sativa L.) plants exhibiting symptoms indicative of ALuY (4) in a seed lucerne paddock (cv CW 5558) at Griffith, southwestern New South Wales (NSW), Australia, in November 2005 and again in January 2006. Samples were kept at 4°C and processed within 36 h of collection. Total DNA was extracted from approximately 0.3 g of leaf midribs and petioles of each plant sample and used as template in a nested PCR assay with phytoplasma universal primer pairs P1/P7 and fU5/m23sr. PCR products resulting from the first amplification were diluted (1:30) with sterile distilled water (SDW) before reamplification with fU5/m23sr. DNA of Australian tomato big bud (TBB) phytoplasma and SDW were used as positive and negative assay controls, respectively. Ten of fifteen plant samples collected in November tested positive for phytoplasma DNA. Restriction digestion profiles of nested PCR amplicons with HpaII endonuclease were the same for all symptomatic plants but differed from the control. Phytoplasma identity was determined by sequencing two nested PCR products that yielded identical sequences. One was deposited in the GenBank database (Accession No. DQ786394). BLAST analysis of the latter sequence revealed a >99.6% similarity with "Candidatus Phytoplasma australiense" (L76865) and related strains papaya dieback (Y10095), phormium yellow leaf (U43570), strawberry green petal (AJ243044), and strawberry lethal yellows (AJ243045). Direct PCR with primers FP 5'-GCATGTCGCGGTGAATAC-3' and RY 5'-TGAGCTATAGGCCCTTAATC-3' designed to specifically amplify DNA of "Ca. P. australiense" detected the phytoplasma in 8 of 40 samples collected in January. Whether this phytoplasma is the etiological agent solely responsible for ALuY is currently under investigation. "Ca. P. asteris" and stolbur group (16SrXII) phytoplasmas have been reported in lucerne in the United States (2) and Italy (1), respectively. Within the stolbur group 16SrXII, "Ca. P. australiense" and stolbur phytoplasma are regarded as separate species and both are distinct from "Ca. P. asteris", a group 16SrI strain. To our knowledge, this is the first report of a "Ca. P. australiense" related strain in lucerne. References: (1) C. Marzachi et al. J. Plant Pathol. 82:201, 2000. (2) R. D. Peters et al. Plant Dis. 83:488, 1999. (3) L. J. Pilkington et al. Australas. Plant Pathol. 28:253, 1999. (4) L. J. Pilkington et al. First report of a phytoplasma associated with 'Australian lucerne yellows' disease. New Disease Report. Online publication at http://www.bspp.org.uk/ndr/jan2002/2001-46.asp .

Effect of cover crops and cultural treatments on plant parasitic nematode density, fungal root disease severity and yield in white clover

Maize (Zea mays), sorghum (Sorghum bicolor), rapeseed (Brassica napus) and molasses grass (Melinis minutiflora) were tested for their ability to host clover root-knot nematodeMeloidogyne trifoliophila in a glasshouse pot experiment and were found to be a poor hosts. A second experiment determined the value of these plants as soil amendments in reducing nematode numbers or improving white clover (Trifolium repens) growth. The effects of these crops together with a range of cultural treatments were also evaluated in a field experiment at Wollongbar Agricultural Institute, New South Wales, Australia, for their impact on nematode population and root rot disease severity. A chopped shoot amendment of sorghum was effective (P<0.05) in reducing the number of root galls and eggs in white clover roots and improving plant growth in the pot test. Overall, cover crop treatments, in particular molasses grass and maize, reduced (P<0.01) field densities of Heterodera trifolii but the population densities recovered quickly after re-establishment of white clover pasture. Dry matter yields were improved only up to 11 weeks after clover establishment. Although cover crops showed potential for improving yield and in reducing the population of certain nematodes, removal of white clover pasture for 5 months as a management practice does not appear to be useful in overcoming root and stolon rot diseases of white clover in this subtropical climate.

Survey of fungi and nematodes associated with root and stolon diseases of white clover in the subtropical dairy region of Australia

A survey of 12 white clover-based dairy pastures on the north coast of New South Wales and south-eastern Queensland, Australia, detected 65 species of fungi and 6 nematode species. The fungi included species of Fusarium, Gliocladium, Codinaea, Alternaria, Colletotrichum, Drechslera, Rhizoctonia, Phoma, Pythium, Phytophthora, Penicillium, Rhizopus and Trichoderma from roots and stolons of white clover. Fungal rots of roots and stolons were most severe during the summer months (November and January samples), while root-knot symptoms caused by plant parasitic nematodes were more severe in June. Sedentary endoparasitic nematodes Meloidogyne trifoliophila, Heterodera trifolii and the ectoparasitic nematode Helicotylenchus dihystera were the numerically dominant nematodes in the region. Other nematode species, including Pratylenchus, Xiphinema and Tylenchorhynchus, were present at lower frequencies and principal component analysis indicated that these were less important as white clover pathogens. Meloidogyne trifoliophila was detected for the first time in Australia and was present at all sites. Many of the fungi and nematodes found are common pathogens of white clover. These pathogens are likely to be contributing to the poor seedling performance, growth and persistence of white clover typical in dairy pastures of the subtropical east coast of Australia.

Pathogenicity of root and stolon-colonising fungi to white clover

Fungi isolated from white clover plants growing in dairy pastures in northern New South Wales and south-eastern Queensland were tested for their pathogenicity to seedlings, excised stolons and mature white clover plants. Thirty out of 65 isolates tested, including species of Fusarium, Phytophthora, Pythium, Rhizoctonia, Phoma, Codinaea, Gliocladium, Microsphaeropsis, Trichoderma, Nectria and Macrophomina, were pathogenic to white clover roots in vitro. Ten of the fungi, including the genera Alternaria, Colletotrichum, Drechslera, Fusarium, Phoma, Macrophomina, Phomopsis and Rhizoctonia, caused stolon rot symptoms. Of the 23 fungi tested on seedlings and mature white clover plants Phytophthora megasperma, Phoma nebulosa and Pythium irregulare were the most pathogenic to both seedlings and mature plants. Root rot and plant growth suppression was more severe in pot tests using field soil compared with pasteurised potting mix. Novel methods are described for testing pathogenicity to excised stolons.

Habitat management to conserve natural enemies of arthropod pests in agriculture

Many agroecosystems are unfavorable environments for natural enemies due to high levels of disturbance. Habitat management, a form of conservation biological control, is an ecologically based approach aimed at favoring natural enemies and enhancing biological control in agricultural systems. The goal of habitat management is to create a suitable ecological infrastructure within the agricultural landscape to provide resources such as food for adult natural enemies, alternative prey or hosts, and shelter from adverse conditions. These resources must be integrated into the landscape in a way that is spatially and temporally favorable to natural enemies and practical for producers to implement. The rapidly expanding literature on habitat management is reviewed with attention to practices for favoring predators and parasitoids, implementation of habitat management, and the contributions of modeling and ecological theory to this developing area of conservation biological control. The potential to integrate the goals of habitat management for natural enemies and nature conservation is discussed.

Efficacy of the insect growth regulators tebufenozide and fenoxycarb for lepidopteran pest control in apples, and their compatibility with biological control for integrated pest management

The insect growth regulators tebufenozide and fenoxycarb were compared with the industry standard organophosphate, azinphos-methyl, in a replicated field trial. In both the 1992-93 and 1993-94 seasons, the 2 insect growth regulators maintained damage levels to harvested and windfall apples below 1% for both codling moth (Cydia pornonella L.) and lightbrown apple moth (Epiphyas postvittana Walker). This was despite considerable pest pressure as indicated by pheromone trap catches of both species. In the first season of the trial, E. postvittana was controlled more effectively (P<0.05) by tebufenozide than by fenoxycarb. In both seasons, populations of two-spotted mite, Tetranychus urticae Koch, and European red mite, Panonychus ulmi Koch, were higher in plots under azinphos-methyl treatment than in either insect growth regulator treatment. Neither insect growth regulator appeared to suppress populations of the phytoseiids Typhlodromus pyri Scheuten and Typhlodromus occidentalis Nesbitt. Limb jarring in the second season showed statistically significant (P<0.05) differences in populations of other predators which may have contributed to the biological control of phytophagous mites in the insect growth regulator treatments. Numbers of spiders, Stethorus spp., and apple dimpling bug (Carnpylomma liebknechti Girault) nymphs were all lower in the azinphos-methyl treatment. Results are discussed in relation to reducing dependence on conventional pesticides by use of more target-specific compounds which may be more compatible with biological control.