Are we focussing wild dog control the wrong time of the year and going about it the wrong way?

Our evaluation of the predation of calves by wild dogs in the 1990s found that the number of calves killed and frequency of years that calf losses occurred, is higher in baited areas compared to adjoining, non-baited areas of similar size. Calf losses were highest with poor seasonal conditions, low prey numbers and where baited areas were re-colonised by wild dogs soon after baiting. We monitored wild dog “activity” before and after 35 baiting programs in southwest, central west and far north Queensland between 1994 and 2006 and found change in activity depends on the timing of the baiting. Baiting programs conducted between October and April show an increase in dog activity post-baiting (average increase of 219.1%, SEM 100.9, n=9, for programs conducted in October and November; an increase of 82.5%, SEM 54.5, n=7 for programs conducted in March and April; and a decrease in activity of 46.5%, SEM 10.2, n=19 for programs conducted between May and September). We monitored the seasonal activity and dispersal of wild dogs fitted with satellite transmitters 2006 to present. We have found that: • Activity of breeding males and females, whilst rearing and nurturing pups, is focussed around the den between July to September and away from areas of human activity. Activity of breeding groups appears to avoid locations of human activity until juveniles become independent (around late November). • While independent and solitary yearlings often have unstable, elliptically-shaped territories in less favourable areas, members of breeding groups have territories that appear seasonally stable and circular located in more favourable habitats. • Extra-territorial forays of solitary yearlings can be huge, in excess of 200 km. The largest forays we have monitored have occurred when the activity of pack members is focussed around rearing pups and juveniles (August to November). • Where wild dogs have dispersed or had significant territorial expansion, it has occurred within days of baiting programs and onto recently baited properties. • The wild dogs we have tracked have followed netting barrier fences for hundreds of kilometres and lived adjacent to or bypassed numerous grids in the barrier. Based on these studies, we conclude that a proportion of the perceived decline in dog activity between May and September, post baiting, is due to a decline in dog activity in areas associated with human activity. The increase in dog activity post-baiting between October and May (and increased calf predation on baited properties) is likely caused by wild dogs dispersing (juveniles and yearlings) or expanding (adults) their territory into baited, now ‘vacant’, areas. We hypothesise that baiting programs should be focussed in summer and autumn commencing late November as soon as juveniles become independent of adults. We also hypothesise that instead of large, annual or semi-annual baiting programs, laying the same number of baits over 4-6 weeks may be more effective. These hypotheses need to be tested through an adaptive management project.

The introduction and release of Chiasmia inconspicua and C. assimilis (Lepidoptera: Geometridae) for the biological control of Acacia nilotica in Australia

Two geometrid moths Chiasmia inconspicua and Chiasmia assimilis, identified as potential biological control agents for prickly acacia Acacia nilotica subsp. indica, were collected in Kenya and imported into quarantine facilities in Australia where laboratory cultures were established. Aspects of the biologies of both insects were studied and CLIMEX® models indicating the climatically favourable areas of Australia were developed. Host range tests were conducted using an approved test list of 74 plant species and no-choice tests of neonate larvae placed on both cut foliage and potted plants. C. inconspicua developed through to adult on prickly acacia and, in small numbers, Acacia pulchella. C. assimilis developed through to adult on prickly acacia and also in very small numbers on A. pulchella, A. deanei, A. decurrens, and A. mearnsii. In all experiments, the response on prickly acacia could be clearly differentiated from the responses on the non-target species. Both insects were approved for release in Australia. Over a three-year period releases were made at multiple sites in north Queensland, almost all in inland areas. There was no evidence of either insect's establishment and both colonies were terminated. A new colony of C. assimilis was subsequently established from insects collected in South Africa and releases of C. assimilis from this new colony were made into coastal and inland infestations of prickly acacia. Establishment was rapid at one coastal site and the insect quickly spread to other infestations. Establishment at one inland area was also confirmed in early 2006. The establishment in coastal areas supported a CLIMEX model that indicated that the climate of coastal areas was more suitable than inland areas.

The suitability of non-target native mangroves for the survival and development of the lantana bug Aconophora compressa, an introduced weed biological control agent

Aconophora compressa (Hemiptera: Membracidae), a biological control agent introduced against the weed Lantana camara (Verbenaceae) in Australia, has since been observed on several non-target plant species, including native mangrove Avicennia marina (Acanthaceae). In this study we evaluated the suitability of two native mangroves, A. marina and Aegiceras corniculatum (Myrsinaceae), for the survival and development of A. compressa through no-choice field cage studies. The longevity of females was significantly higher on L. camara (57.7 ± 3.8 days) than on A. marina (43.3 ± 3.3 days) and A. corniculatum (45.7 ± 3.8 days). The proportion of females laying eggs was highest on L. camara (72%) followed by A. marina (36%) and A. corniculatum (17%). More egg batches per female were laid on L. camara than on A. marina and A. corniculatum. Though more nymphs per shoot emerged on L. camara (29.9 ± 2.8) than on A. marina (13 ± 4.8) and A. corniculatum (10 ± 5.3), the number of nymphs that developed through to adults was not significantly different. The duration of nymphal development was longer on A. marina (67 ± 5.8 days) than on L. camara (48 ± 4 days) and A. corniculatum (43 ± 4.6 days). The results, which are in contrast to those from previous glasshouse and quarantine trials, provide evidence that A. compressa adults can survive, lay eggs and complete nymphal development on the two non-target native mangroves in the field under no-choice condition.

The leaf-tying moth Hypocosmia pyrochroma (Lep., Pyralidae), a host-specific biological control agent for cat's claw creeper Macfadyena unguis-cati (Bignoniaceae) in Australia

Cat's claw creeper, Macfadyena unguis-cati, a major environmental weed in coastal and sub-coastal areas of Queensland and New South Wales, Australia is a target for classical biological control. Host specificity of Hypocosmia pyrochroma Jones (Lep., Pyralidae), as a potential biological control agent was evaluated on the basis of no-choice and choice larval feeding and survival, and adult oviposition preference tests, involving 38 plant species in 10 families. In no-choice tests, larval feeding and development occurred only on cat's claw creeper. In choice tests, oviposition and larval development was evident only on cat's claw creeper. The results support the host-specificity tests conducted in South Africa, and suggest that H. pyrochroma is a highly specific biological control agent that does not pose any risk to non-target plants tested in Australia. This agent has been approved for field release by relevant regulatory authorities in Australia.

The host range of Isturgia deeraria, an insect considered for the biological control of Acacia nilotica in Australia

The geometrid caterpillar Isturgia deerraria was imported from Kenya into quarantine facilities in Australia as a potential biological control agent for prickly acacia, Acacia nilotica subsp. indica (Benth.) Brenan (family Mimosaceae). The insect was then tested on 30 plant species presented to neonate larvae as a no-choice cut foliage test and 13 plant species presented as a no-choice potted plant test. In these tests the insect was able to complete its life cycle on 13 native Acacia spp. and also on Acacia farnesiana and the exotic ornamental Delonix regia (family Caesalpiniaceae). The tests supported field observations that the insect has a host range spanning many leguminous species and as such the insect could not be considered for release in Australia.

Clinging on: a review on the biological control of cat’s claw creeper

Cat's claw creeper, a native of South America and an escaped ornamental, is a serious environmental weed in Australia, South Africa and also several other countries. This paper reviews the efforts made over the last decade to bring about its biological control. The paper describes the weed status of cat's claw creeper in both Australia and South Africa. These two countries have cooperated in developing biocontrol projects and insect agents have now been released in both countries. These insects and other potential agents are described and suggestions made for the future direction of the projects.

Individual-based modelling of the efficacy of fumigation tactics to control lesser grain borer (Rhyzopertha dominica) in stored grain

Increasing resistance to phosphine (PH 3) in insect pests, including lesser grain borer (Rhyzopertha dominica) has become a critical issue, and development of effective and sustainable strategies to manage resistance is crucial. In practice, the same grain store may be fumigated multiple times, but usually for the same exposure period and concentration. Simulating a single fumigation allows us to look more closely at the effects of this standard treatment.We used an individual-based, two-locus model to investigate three key questions about the use of phosphine fumigant in relation to the development of PH 3 resistance. First, which is more effective for insect control; long exposure time with a low concentration or short exposure period with a high concentration? Our results showed that extending exposure duration is a much more efficient control tactic than increasing the phosphine concentration. Second, how long should the fumigation period be extended to deal with higher frequencies of resistant insects in the grain? Our results indicated that if the original frequency of resistant insects is increased n times, then the fumigation needs to be extended, at most, n days to achieve the same level of insect control. The third question is how does the presence of varying numbers of insects inside grain storages impact the effectiveness of phosphine fumigation? We found that, for a given fumigation, as the initial population number was increased, the final survival of resistant insects increased proportionally. To control initial populations of insects that were n times larger, it was necessary to increase the fumigation time by about n days. Our results indicate that, in a 2-gene mediated resistance where dilution of resistance gene frequencies through immigration of susceptibles has greater effect, extending fumigation times to reduce survival of homozygous resistant insects will have a significant impact on delaying the development of resistance. © 2012 Elsevier Ltd.

The leaf-feeding geometrid Isturgia disputaria (Guenee)-A potential biological control agent for prickly acacia, Vachellia nilotica subsp. indica (Benth.) Kyal. & Boatwr. (Mimosaceae) in Australia

Prickly acacia (Vachellia nilotica subsp. indica), a native multipurpose tree in India, is a weed of National significance, and a target for biological control in Australia. Based on plant genetic and climatic similarities, native range surveys for identifying potential biological control agents for prickly acacia were conducted in India during 2008-2011. In the survey leaf-feeding geometrid, Isturgia disputaria Guenee (syn. Tephrina pulinda), widespread in Tamil Nadu and Karnataka States, was prioritized as a potential biological control agent based on field host range, damage potential and no choice test on non target plant species. Though the field host range study exhibited that V. nilotica ssp. indica and V. nilotica ssp. tomentosa were the primary hosts for successful development of the insect, I. disputaria, replicated no - choice larval feeding and development tests conducted on cut foliage and live plants of nine non-target acacia test plant species in India revealed the larval feeding and development on three of the nine non-target acacia species, V. tortilis, V. planiferons and V. leucophloea in addition to the V. nilotica ssp. indica and V. nilotica ssp. tomentosa. However, the proportion of larvae developing into adults was higher on V. nilotica subsp. indica and V. nilotica subsp. tomentosa, with 90% and 80% of the larvae completing development, respectively. In contrast, the larval mortality was higher on V. tortilis (70%), V. leucophloea (90%) and V. planiferons (70%). The no-choice test results support the earlier host specificity test results of I. disputaria from Pakistan, Kenya and under quarantine in Australia. Contrasting results between field host range and host use pattern under no-choice conditions are discussed.

The status of weed biological control in Vanuatu

Biological control of weeds in Vanuatu began in 1935, with the introduction of the tingid Teleonemia scrupulosa to control Lantana camara. To date, nine biological control agents have been intentionally introduced to control eight weed species. Seven of these agents have established on their respective hosts while an eighth, Zygogramma bicolorata, an agent for Parthenium hysterophorus has only recently been released and establishment is unlikely. The fate of a ninth agent, Heteropsylla spinulosa, released for the control of Mimosa diplotricha is unclear. Six other biological control agents, including Epiblema strenuana which was first detected in 2014 on P. hysterophorus on Efate have spread into the country unintentionally. Control of the target weeds range from inadequate to very good. By far the most successful agent has been Calligrapha pantherina which was introduced to control Sida acuta and Sida rhombifolia. The beetle was released on 14 islands and managed to spread to at least another 10 islands where it has effectively controlled both Sida spp. Control of the two water weeds, Eichhornia crassipes by Neochetina bruchi and N. eichhorniae and Pistia stratiotes by Neohydronomus affinis, has also been fairly good in most areas. Two agents, T. scrupulosa and Uroplata girardi, were released on L. camara, and four other agents have been found on the weed, but L. camara is still not under adequate control. The rust Puccinia spegazzinii was first released on Mikania micrantha in 2012 and successfully established. Anecdotal evidence suggests that it is having an impact on M. micrantha, but detailed monitoring is required to determine its overall impact. Future prospects for weed biological control in Vanuatu are positive, with the expected greater spread of recently released agents and the introduction of new agents for P. hysterophorus, L. camara, Dolichandra unguis-cati and Spathodea campanulata.

Timing of fungicide applications for control of husk spot caused by Pseudocercospora macadamiae in macadamia

Pseudocercospora macadamiae is an important pathogen of macadamia in Australia, causing a disease known as husk spot. Growers strive to control the disease with a number of carbendazim and copper treatments. The aim of this study was to consider the macadamia fruit developmental stage at which fungicide application is most effective against husk spot, and whether application of copper-only applications at full-size fruit developmental stage toward the end of the season contributed to effective disease control. Fungicides were applied to macadamia trees at four developmental stages in three orchards in two subsequent production seasons. The effects of the treatments on disease incidence and severity were quantified using area under disease progress curve (AUDPC) and logistic regression models. Although disease incidence varied between cultivars, incidence and severity on cv. A16 showed consistent differences between the treatments. Most significant reduction in husk spot incidence occurred when spraying commenced at match-head sized-fruit developmental stage. All treatments significantly reduced husk spot incidence and severity compared with the untreated controls, and a significant positive linear relationship (R2 = 73%) between AUDPC and severity showed that timing of the first fungicide application is important for effective disease control. Application of fungicide at full-size fruit stage reduced disease incidence but had no impact on premature fruit drop.

Impact of resistance on the efficacy of binary combinations of spinosad, chlorpyrifos-methyl and s-methoprene against five stored-grain beetles

Laboratory experiments were conducted to determine the efficacy of spinosad (a biopesticide), chlorpyrifos-methyl (an organophosphorus compound (OP)) and s-methoprene (a juvenile hormone analogue) applied alone and in binary combinations against five stored-grain beetles in wheat. There were three strains of Rhyzopertha dominica, and one strain each of Sitophilus oryzae, Tribolium castaneum, Oryzaephilus surinamensis and Cryptolestes ferrugineus. These strains were chosen to represent a range of possible resistant genotypes, exhibiting resistance to organophosphates, pyrethroids or methoprene. Treatments were applied at rates that are registered or likely to be registered in Australia. Adults were exposed to freshly treated wheat for 2 weeks, and the effects of treatments on mortality and reproduction were determined. No single protectant or protectant combination controlled all insect strains, based on the criterion of >99% reduction in the number of live F1 adults relative to the control. The most effective combinations were spinosad at 1 mg kg-1+chlorpyrifos-methyl at 10 mg kg-1 which controlled all strains except for OP-resistant O. surinamensis, and chlorpyrifos-methyl at 10 mg kg-1+s-methoprene at 0.6 mg kg-1 which controlled all strains except for methoprene-resistant R. dominica. The results of this study demonstrate the difficulty in Australia, and potentially other countries which use protectants, of finding protectant treatments to control a broad range of pest species in the face of resistance development.

Potential of imidacloprid to control four species of psocids (Psocoptera: Liposcelididae) infesting stored grain

The effectiveness of the neonicotinoid insecticide imidacloprid was evaluated against four psocid pests of stored grain. This research was undertaken because of the growing importance of psocids in stored grain and the need to identify methods for their control. The mortality and reproduction of adults of Liposcelis bostrychophila Badonnel, L. entomophila (Enderlein), L. decolor (Pearman) and L. paeta Pearman in wheat treated with imidacloprid were determined. There were five application rates (0.5, 1, 2, 5 and 10 mg AI kg -1 grain) and an untreated control. There were significant effects of application rate on both adult mortality and reproduction for all four species, but the effect of imidacloprid was sometimes more pronounced on reproduction. Imidacloprid was most effective against L. bostrychophila, with 100% adult mortality after 7 d at 5 mg AI kg-1, 14 d at 2 mg AI kg-1 and 28 d at 0.5 and 1 mg AI kg-1. No live progeny were produced at 2 mg AI kg-1. For L. decolor, there was 100% adult mortality after 28 d at 10 mg AI kg-1 and no live progeny were produced at 2 mg AI kg-1. For L. entomophila, there was 100% adult mortality after 14 d at 10 mg AI kg-1 and 28 d at 2 and 5 mg AI kg-1. No live progeny were produced at 10 mg AI kg-1. At 10 mg AI kg-1 there was 100% mortality of L. paeta adults after 28 d exposure and no live progeny developed. Because reproduction at some application rates occurred only in the first 14 d of exposure, it is concluded that the application rate leading to population extinction was 1 mg AI kg-1 for L. bostrychophila, 2 mg AI kg-1 for L. decolor and L. entomophila and 5 mg AI kg -1 for L. paeta. This study shows that imidacloprid has potential as a grain protectant to control all four Liposcelis species in stored grain.

Grazing management influences the dynamics of populations of Stylosanthes hippocampoides (Oxley fine stem stylo)

This paper describes a study to identify those factors which control the persistence of the Subtropical legume Stylosanthes hippocampoides, formerly S. guianensis cv. Oxley (fine stem stylo). The dynamics of S. hippocampoides populations was recorded in permanent quadrats at 2 stocking rates in a grazing study conducted between 1987 and 1992 in south-eastern Queensland. Density of mature plants fluctuated between 10 and 60 plants/m(2) during the 5 years with the major contributing factors being variations in seedling recruitment and survival, which, in turn, reflected the size of the soil seed bank and seasonal rainfall. Plant density was consistently higher at the lower stocking rate of 1 beast/1.5 ha compared with 1 beast/1 ha; however, the effect of stocking rate was minor compared with fluctuation due to seasonal variation in rainfall. The maximum life span of the original plants exceeded 5 years, while the survival of seedling cohorts was strongly impacted by seasonal rainfall. Total exclosure from grazing during summer increased the size of the soil seed bank although a precise time period during summer was not identified, while grazing at the lower stocking pressure produced the same outcome. It was concluded that the large seasonal variation that occurs in S. hippocampoides density is driven by large seasonal variation in seedling recruitment, which, in turn, is influenced by the size of the soil seed bank.