Species and Hybrids: Chemical and Physical Foliar Attributes and Implications for Herbivory.

Hybridization is an important biological phenomenon that can be used to understand the evolutionary process of speciation of plants and their associated pests and diseases. Interactions between hybrid plants and the herbivores of the parental taxa may be used to elucidate the various cues being used by the pests for host location or other processes. The chemical composition of plants, and their physical foliar attributes, including leaf thickness, trichome density, moisture content and specific leaf weight were compared between allopatric pure and commercial hybrid species of Corymbia, an important subtropical hardwood taxon. The leaf-eating beetle Paropsis atomaria, to which the pure taxa represented host (C. citriodora subsp. variegata) and non-host (C. torelliana) plants, was used to examine patterns of herbivory in relation to these traits. Hybrid physical foliar traits, chemical profiles, and field and laboratory beetle feeding preference, while showing some variability, were generally intermediate to those exhibited by parent taxa, thus suggesting an additive inheritance pattern. The hybrid susceptibility hypothesis was not supported by our field or laboratory studies, and there was no strong relationship between adult preference and larval performance. The most-preferred adult host was the sympatric taxon, although this species supported the lowest larval survival, while the hybrid produced significantly smaller pupae than the pure species. The results are discussed in relation to plant chemistry and physical characteristics. The findings suggest a chemical basis for host selection behavior and indicate that it may be possible to select for resistance to this insect pest in these commercially important hardwood trees.

Thermal tolerance and potential distribution of Carvalhotingis visenda (Hemiptera: Tingidae), a biological control agent for cat's claw creeper, Macfadyena unguis-cati (Bignoniaceae)

The specialist tingid, Carvalhotingis visenda, is a biological control agent for cat's claw creeper, Macfadyena unguis-cati (Bignoniaceae). Cat's claw creeper is an invasive liana with a wide climatic tolerance, and for biological control to be effective the tingid must survive and develop over a range of temperatures. We evaluated the effect of constant temperatures (0-45°C) on the survival and development of C. visenda. Adults showed tolerance for wider temperature ranges (0-45°C), but oviposition, egg hatching and nymphal development were all affected by both high (>30°C) and low (<20°C) temperatures. Temperatures between 20°C and 30°C are the most favourable for adult survival, oviposition, egg hatching and nymphal development. The ability of adults and nymphs to survive for a few days at high (40°C and 45°C) and low (0°C and 5°C) temperatures suggest that extreme temperature events, which usually occur for short durations (hours) in cat's claw creeper infested regions in Queensland and New South Wales states are not likely to affect the tingid population. The potential number of generations (egg to adult) the tingid can complete in a year in Australia ranged from three to eight, with more generations in Queensland than in New South Wales.

The effect of data sources and quality on the predictive capacity of CLIMEX models: an assessment of Teleonemia scrupulosa and Octotoma scabripennis for the biocontrol of Lantana camara in Australia

Understanding the effects of different types and quality of data on bioclimatic modeling predictions is vital to ascertaining the value of existing models, and to improving future models. Bioclimatic models were constructed using the CLIMEX program, using different data types – seasonal dynamics, geographic (overseas) distribution, and a combination of the two – for two biological control agents for the major weed Lantana camara L. in Australia. The models for one agent, Teleonemia scrupulosa Stål (Hemiptera:Tingidae) were based on a higher quality and quantity of data than the models for the other agent, Octotoma scabripennis Guérin-Méneville (Coleoptera: Chrysomelidae). Predictions of the geographic distribution for Australia showed that T. scrupulosa models exhibited greater accuracy with a progressive improvement from seasonal dynamics data, to the model based on overseas distribution, and finally the model combining the two data types. In contrast, O. scabripennis models were of low accuracy, and showed no clear trends across the various model types. These case studies demonstrate the importance of high quality data for developing models, and of supplementing distributional data with species seasonal dynamics data wherever possible. Seasonal dynamics data allows the modeller to focus on the species response to climatic trends, while distributional data enables easier fitting of stress parameters by restricting the species envelope to the described distribution. It is apparent that CLIMEX models based on low quality seasonal dynamics data, together with a small quantity of distributional data, are of minimal value in predicting the spatial extent of species distribution.

Characterising insect plant host relationships facilitates understanding multiple host use

Weed biocontrol relies on host specificity testing, usually carried out under quarantine conditions to predict the future host range of candidate control agents. The predictive power of host testing can be scrutinised directly with Aconophora compressa, previously released against the weed Lantana camara L. (lantana) because its ecology in its new range (Australia) is known and includes the unanticipated use of several host species. Glasshouse based predictions of field host use from experiments designed a posteriori can therefore be compared against known field host use. Adult survival, reproductive output and egg maturation were quantified. Adult survival did not differ statistically across the four verbenaceous hosts used in Australia. Oviposition was significantly highest on fiddlewood (Citharexylum spinosum L.), followed by lantana, on which oviposition was significantly higher than on two varieties of Duranta erecta (‘‘geisha girl’’ and ‘‘Sheena’s gold’’; all Verbenaceae). Oviposition rates across Duranta varieties were not significantly different from each other but were significantly higher than on the two non-verbenaceous hosts (Jacaranda mimosifolia D. Don: Bignoneaceae (jacaranda) and Myoporum acuminatum R. Br.: Myoporaceae (Myoporum)). Production of adult A. compressa was modelled across the hosts tested. The only major discrepancy between model output and their relative abundance across hosts in the field was that densities on lantana in the field were much lower than predicted by the model. The adults may, therefore, not locate lantana under field conditions and/or adults may find lantana but leave after laying relatively few eggs. Fiddlewood is the only primary host plant of A. compressa in Australia, whereas lantana and the others are used secondarily or incidentally. The distinction between primary, secondary and incidental hosts of a herbivore species helps to predict the intensity and regularity of host use by that herbivore. Populations of the primary host plants of a released biological control agent are most likely to be consistently impacted by the herbivore, whereas secondary and incidental host plant species are unlikely to be impacted consistently. As a consequence, potential biocontrol agents should be released only against hosts to which they have been shown to be primarily adapted.

Classical Biological Control for the Protection of Natural Ecosystems.

Of the 70 cases of classical biological control for the protection of nature found in our review, there were fewer projects against insect targets (21) than against invasive plants (49), in part, because many insect biological control projects were carried out against agricultural pests, while nearly all projects against plants targeted invasive plants in natural ecosystems. Of 21 insect projects, 81% (17) provided benefits to protection of biodiversity, while 48% (10) protected products harvested from natural systems, and 5% (1) preserved ecosystem services, with many projects contributing to more than one goal. In contrast, of the 49 projects against invasive plants, 98% (48) provided benefits to protection of biodiversity, while 47% (23) protected products, and 25% (12) preserved ecosystem services, again with many projects contributing to several goals. We classified projects into complete control (pest generally no longer important), partial control (control in some areas but not others), and "in progress," for projects in development for which outcomes do not yet exist. For insects, of the 21 projects discussed, 59% (13) achieved complete control of the target pest, 18% (4) provided partial control, and 41% (9) are still in progress. By comparison, of the 49 invasive plant projects considered, 27% (13) achieved complete control, while 33% (16) provided partial control, and 47% (24) are still in progress. For both categories of pests, some projects' success ratings were scored twice when results varied by region. We found approximately twice as many projects directed against invasive plants than insects and that protection of biodiversity was the most frequent benefit of both insect and plant projects. Ecosystem service protection was provided in the fewest cases by either insect or plant biological control agents, but was more likely to be provided by projects directed against invasive plants, likely because of the strong effects plants exert on landscapes. Rates of complete success appeared to be higher for insect than plant targets (59% vs 27%), perhaps because most often herbivores gradually weaken, rather than outright kill, their hosts, which is not the case for natural enemies directed against pest insects. For both insect and plant biological control, nearly half of all projects reviewed were listed as currently in progress, suggesting that the use of biological control for the protection of wildlands is currently very active.

Resin-foraging by colonies of Trigona sapiens and T. hockingsi (Hymenoptera: Apidae, Meliponini) and consequent seed dispersal of Corymbia torelliana (Myrtaceae).

Resins are a critical resource for stingless bees and resin-collecting bees act as seed dispersers in tropical plants. We describe the diurnal foraging patterns of colonies of Trigona sapiens and T. hockingsi on resin and pollen. We also document patterns of waste removal and seed dispersal of Corymbia torelliana. At most, only 10% of foragers collected resin or dispersed seed. Nevertheless, bees dispersed 1-3 seeds outside the nest per 5 minutes, and 38-114 seeds per day for each nest. The proportion of returning bees carrying pollen was highest in the morning for both species. The proportion of foragers returning with resin loads showed no significant diurnal variation in any season. Waste removal activity peaked in the afternoon for T. sapiens and in the morning for T. hockingsi. Seed removal peaked in the afternoon in one year only for T. sapiens. Bees dispersed thousands of seeds of C. torelliana over the season even though only a small proportion of the colony was engaged in seed transport.

Evaluation of existing and new insecticides including spirotetramat and pyridalyl to control Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) on peppers in Queensland.

Insecticides are used by growers to control Frankliniella occidentalis (western flower thrips) in Australian vegetable crops. However, limited information was available on the efficacy of some insecticides used against F. occidentalis and data on new insecticides that could be included in a resistance management program were required. The efficacy of 16 insecticides in controlling F. occidentalis was tested in four small plot trials in chillies and capsicums. Spinosad, fipronil and methamidophos were effective against adults and larvae. Spirotetramat had no efficacy against adults but was very effective against larvae. Pyridalyl was moderately effective against larvae. Methidathion showed limited effectiveness. Abamectin, amorphous silica, bifenthrin, chlorpyrifos, dimethoate, emamectin benzoate, endosulfan, imidacloprid, methomyl and insecticidal soap were not effective. Laboratory bioassays on F. occidentalis collected from the field trials showed resistance to bifenthrin but not to the other insecticides tested. The trials demonstrated that some insecticides permitted for use against F. occidentalis are not effective and identified a number of insecticides, including the new ones spirotetramat and pyridalyl, that are effective and that could be used to manage the pest within a resistance management program.

The use of temperate species in the Australian subtropics.

Temperate species and tropical crop silage are the basis for forage production for the dairy industry in the Australian subtropics. Irrigation is the key resource needed for production, with little survival of temperate species under rain-grown conditions except for lucerne. Annual ryegrass (Lolium multiflorum), fertilised with either inorganic nitrogen or grown with clovers, is the main cool season forage for the dairy industry. It is sown into fully prepared seedbeds, oversown into tropical grasses, especially kikuyu (Pennisetum clandestinum) or sown after mulching. There has been a continual improvement in the performance of annual and hybrid ryegrass cultivars over the last 25 years. In small plot, cutting experiments, yields of annual ryegrass typically range from 15 to 21 t DM/ha, with equivalent on-farm yields of 7 to 14 t DM/ha of utilised material. Rust (Puccinia coronata) remains the major concern although resistance is more stable than in oats. There have also been major improvements in the performance of perennial ryegrass (L. perenne) cultivars although their persistence under grazing is insufficient to make them a reliable forage source for the subtropics. On the other hand, tall fescue (Festuca arundinacea) and prairie grass (Bromus willdenowii) cultivars perform well under cutting and grazing, although farmer resistance to the use of tall fescue is strong. White clover (Trifolium repens) is a reliable and persistent performer although disease usually reduces its performance in the third year after sowing. Persian (Shaftal) annual clover (T. resupinatum) gives good winter production but the performance of berseem clover (T. alexandrinum) is less reliable and the sub clovers (T. subterraneum) are generally not suited to clay soils of neutral to alkaline pH. Lucerne (Medicago sativa), either as a pure stand or in mixtures, is a high producing legume under both irrigation and natural rainfall. Understanding the importance of leaf and crown diseases, and the development of resistant cultivars, have been the reasons for its reliability. Insects on temperate species are not as serious a problem in the subtropics as in New Zealand (NZ). Fungal and viral diseases, on the other hand, cause many problems and forage performance would benefit from more research into resistance.

Introduction and establishment of Carvalhotingis visenda (Hemiptera: Tingidae) as a biological control agent for cat's claw creeper Macfadyena unguis-cati (Bignoniaceae) in Australia

Carvalhotingis visenda (Hemiptera: Tingidae) is the first biological control agent approved for release against cat’s claw creeper Macfadyena unguis-cati (Bignoniaceae) in Australia. The mass-rearing and field releases of C. visenda commenced in May 2007 and since then more than half a million individuals have been released at 72 sites in Queensland and New South Wales. In addition, community groups have released over 11,000 tingid-infested potted cat’s claw creeper plants at 63 sites in Queensland. Establishment of C. visenda was evident at 80% of the release sites after three years. The tingid established on the two morphologically distinct ‘long-pod’ and ‘short-pod’ cat’s claw creeper varieties present in Australia. Establishment was more at sites that received three or more field releases (83%) than at sites that received two or less releases (73%); and also at sites that received more than 5000 individuals (82%) than at sites that received less than 5000 individuals (68%). In the field, the tingid spread slowly (5.4 m per year), and the maximum distance of C. visenda incidence away from the initial release points ranged from 6 m to approximately 1 km.

Australia takes prickly acacia biocontrol search to India

A project co-funded by Meat & Livestock Australia and the Queensland Government is putting new life into the search for biocontrol agents for prickly acacia (Acacia nilotica), a Weed of National Significance in Australia.

Refining the process of agent selection through understanding plant demography and plant response to herbivory

Understanding plant demography and plant response to herbivory is critical to the selection of effective weed biological control agents. We adopt the metaphor of 'filters' to suggest how agent prioritisation may be improved to narrow our choices down to those likely to be most effective in achieving the desired weed management outcome. Models can serve to capture our level of knowledge (or ignorance) about our study system and we illustrate how one type of modelling approach (matrix models) may be useful in identifying the weak link in a plant life cycle by using a hypothetical and an actual weed example (Parkinsonia aculeata). Once the vulnerable stage has been identified we propose that studying plant response to herbivory (simulated and/or actual) can help identify the guilds of herbivores to which a plant is most likely to succumb. Taking only potentially effective agents through the filter of host specificity may improve the chances of releasing safe and effective agents. The methods we outline may not always lead us definitively to the successful agent(s), but such an empirical, data-driven approach will make the basis for agent selection explicit and serve as testable hypotheses once agents are released.

Selectivity of chlorantraniliprole to parasitoid wasps.

BACKGROUND: Chlorantraniliprole is a novel anthranilic diamide insecticide registered for use in vegetables, fruits, grains and turf against a variety of insect pests. The objective of this article is to summarize results of acute toxicity testing of chlorantraniliprole on seven species of parasitic wasps with wide geographic distribution and relevance to different crops and integrated pest management (IPM) programmes. RESULTS: Tier-1, worst-case laboratory studies evaluated wasp survival and reproduction following different exposure concentrations and scenarios to chlorantraniliprole (i.e. fresh-dried spray deposits on glass plates, direct contact, ingestion, egg card, dipped leaf residue bioassays, sprayed mummies). No statistically significant effects on adult survival, percentage parasitism or emergence were observed following exposures to chlorantraniliprole compared with controls. CONCLUSION: Chlorantraniliprole was harmless to the parasitoid wasp species tested according to IOBC classification criteria (<30% effects) and may be a useful tool in IPM programmes.

Specific detection of the Old World screwworm fly, Chrysomya bezziana, in bulk fly trap catches using real-time PCR.

The Old World screwworm fly (OWS), Chrysomya bezziana Villeneuve (Diptera: Calliphoridae), is a myiasis-causing blowfly of major concern for both animals and humans. Surveillance traps are used in several countries for early detection of incursions and to monitor control strategies. Examination of surveillance trap catches is time-consuming and is complicated by the presence of morphologically similar flies that are difficult to differentiate from Ch. bezziana, especially when the condition of specimens is poor. A molecular-based method to confirm or refute the presence of Ch. bezziana in trap catches would greatly simplify monitoring programmes. A species-specific real-time polymerase chain reaction (PCR) assay was designed to target the ribosomal DNA internal transcribed spacer 1 (rDNA ITS1) of Ch. bezziana. The assay uses both species-specific primers and an OWS-specific Taqman MGB probe. Specificity was confirmed against morphologically similar and related Chrysomya and Cochliomyia species. An optimal extraction protocol was developed to process trap catches of up to 1000 flies and the assay is sensitive enough to detect one Ch. bezziana in a sample of 1000 non-target species. Blind testing of 29 trap catches from Australia and Malaysia detected Ch. bezziana with 100% accuracy. The probability of detecting OWS in a trap catch of 50 000 flies when the OWS population prevalence is low (one in 1000 flies) is 63.6% for one extraction. For three extractions (3000 flies), the probability of detection increases to 95.5%. The real-time PCR assay, used in conjunction with morphology, will greatly increase screening capabilities in surveillance areas where OWS prevalence is low.

A review of Taenaris Hubner (Lepidoptera: Nymphalidae: Amathusiinae) in Queensland, together with first Australian records for T. myops kirschi Staudinger and Elymnias agondas melanippe Grose-Smith (Satyrinae).

Species of the amathusiine genus Taenaris Hubner known to occur in Australia, predominantly from Torres Strait, are reviewed and illustrated. T. myops kirschi Staudinger is recorded for the first time in Australia from four male specimens collected on Dauan Island, Torres Strait. A female specimen of the satyrine Elymnias agondas melanippe Grose-Smith also collected from Dauan Island represents the first record of this taxon from Australia. The high degree of variation observed in the external facies of Taenaris from Torres Strait and reliable taxonomic separation of female specimens are discussed. Taenaris-like forms of the papilionid, Papilio aegeus ormenus Guerin-Meneville and E. a. melanippe from Torres Strait and Dauan Island respectively are illustrated and reviewed. The form of P. a. ormenus from Torres Strait that is most similar to Taenaris spp. is identified as form ormenus Guerin-Meneville variety onesimus Hewitson.

Improved termite resistance of wood by wax impregnation.

We investigated the effect of wax-treated and biocide-free wood specimens against three different termite species. A laboratory no-choice test with Reticulitermes banyulensis Clément was carried out in Valencia (Spain) under Mediterranean conditions for eight weeks. Scots pine sapwood (Pinus sylvestris L.) fully impregnated with distinct waxes was used. Two field trials were conducted with Coptotermes acinaciformis (Froggatt) and Mastotermes darwiniensis Froggatt in northern Queensland (Australia) with wax-impregnated beech (Fagus sylvatica L.) for 16 weeks. All three subterranean termites are of major economic importance in their respective regions. The results indicated that feeding pressure by the termites was sufficient within all trials for a valid test. Wax-impregnated Scots pine sapwood was classified as durable. No termites survived the test. The results showed an aging process under submersion conditions, which lead to a classification of moderately durable. The paraffin treatment showed good termite resistance under both test procedures, and was classified as durable. The Australian field trials showed a decreased mass loss of wax-treated beech, in which an amide wax showed excellent termite resistance. The results indicate a clear dependence of the termite resistance on the type and ratio of wax used and the feeding preferences of the specific termite species.