Patterns of release of the secondary conidia of Claviceps africana, the sorghum ergot pathogen in Australia

Trials were conducted in southern Queensland, Australia between March and May 2003, 2004 and 2005 to study patterns of hourly and daily release of the secondary conidia of Claviceps africana and their relationships with weather parameters. Conidia were trapped for at least one hour on most (> 90%) days in 2003 and 2004, but only on 55% of days in 2005. Both the highest daily concentration of conidia, and the highest number of hours per day when conidia were trapped, were recorded 1-3 days after rainfall events. Although the pattern of conidial release was different every day, the highest hourly conidial concentrations occurred between 10.00 hours and 17.00 hours on 73% of all days in the three trials. Hours when conidia were trapped were characterized by higher median values of temperature, windspeed and vapour pressure deficit, lower relative humidity, and leaf wetness values of 0%, than hours when no conidia were recorded. The results indicate that fungicides need to be applied to the highly ergot-susceptible male sterile (A-) lines of sorghum in hybrid seed production blocks and breeders' nurseries as soon as possible after rainfall events to minimize ergot severity.

Changes in sensory quality of sterile cantaloupe dice stored in controlled atmospheres.

Diced cantaloupe flesh that was microbiologically sterile was prepared in order to study the physiological deterioration of fruit when stored under a range of controlled atmospheres at 4.5°C. Sterile fruit pieces were prepared by boiling whole melons for 3 min, then dicing aseptically. Storage atmospheres were in continuous flow and contained from 0 to 26% CO2 and 3.5 to 17% O2. Sensory assessments were carried out by a highly trained panel at 14-day intervals. Products that were acceptable for up to 28 days were obtained when the following 3 treatments were used: 6% CO2 and 6% O2; 9.5% CO2 and 3.5% O2; and 15% CO2 and 6% O2. Overall, treatment with 0, 19.5 or 26% CO2 (irrespective of O2 concn.) caused significant deterioration in sensory properties.

Alkaloid production by isolates of the sorghum ergot pathogen (Claviceps africana) from Australia and other countries

Isolates of Claviceps africana from Australia, Africa, Asia, and America were tested for the production of dihydroergosine (DHES), and its biogenic precursors dihydroelymoclavine (DHEL) and festuclavine (FEST), in culture. Several growth media were evaluated to optimise alkaloid production with little success. The best of these involved 2-stage culturing on high-sucrose substrate. Australian C. africana isolates varied widely and inconsistently in alkaloid production, with DHES concentrations in mycelium ranging from: <0.1 to 9 mg DHES/kg; <0.1 to 1.6 mg DHEL/kg; and <0.1 to 0.4 mg FEST/kg. In a separate experiment using similar culturing techniques, DHES was produced by 2 of 3 Australian isolates, 1 of 3 USA isolates, 1 of 4 Indian isolates, the sole Puerto Rican isolate, the sole Japanese isolate, but not the sole South African isolate. In this experiment, DHES concentrations detected in mycelium of Australian isolates (0.1-1.0 mg DHES/kg) were of similar magnitude to isolates from other countries (0.2-1.8 mg DHES/kg). Three C. africana isolates, including one that produced only traces of alkaloid in culture after 8 weeks, were inoculated onto panicles of sterile male sorghum plants. After 8 weeks, all 3 isolates produced 10-19 mg DHES/kg in the panicles, demonstrating that the growing plant favoured more consistent alkaloid production than culture medium.

Male traits and herd reproductive capability in tropical beef cattle. 1. Experimental design and animal measures

Research into the genetics of whole herd profitability has been a focus of the Beef Cooperative Research Centre for Beef Genetic Technologies over the past decade and it has been identified that measures of male reproduction may offer a potential indirect means of selecting for improved female reproduction. This paper describes the experimental design and provides a descriptive analysis of an array of male traits in Brahman and Tropical Composite genotypes managed under the medium to high stress, semi-extensive to extensive production systems of northern Australia. A total of 1639 Brahman and 2424 Tropical Composite bulls with known pedigrees, bred and raised in northern Australia, were evaluated for a comprehensive range of productive and reproductive traits. These included blood hormonal traits (luteinising hormone, inhibin and insulin-like growth factor-I); growth and carcass traits (liveweight, body condition score, ultrasound scanned 12-13th rib fat, rump P8 fat, eye muscle area and hip height); adaptation traits (flight time and rectal temperature); and a bull breeding soundness evaluation (leg and hoof conformation, sheath score, length of everted prepuce, penile anatomy, scrotal circumference, semen mass activity, sperm motility and sperm morphology). Large phenotypic variation was evident for most traits, with complete overlap between genotypes, indicating that there is likely to be a significant opportunity to improve bull fertility traits through management and bull selection.

Male traits and herd reproductive capability in tropical beef cattle. 2. Genetic parameters of bull traits

A total of 4063 young bulls of two tropical genotypes (1639 Brahman and 2424 Tropical Composite) raised in northern Australia were evaluated for a comprehensive range of production and reproduction traits up to 24 months of age. Prior to weaning, peripheral blood concentrations of luteinising hormone (LH) and inhibin were measured at 4 months of age. At weaning (6 months) blood insulin-like growth factor-1 (IGF-I) and flight time were recorded. Body composition traits of fat depth and eye-muscle area were determined by ultrasonography at 15 months of age when additional measurements of liveweight, hip height and body condition score were recorded. Bull breeding soundness was evaluated at similar to 12, 18 and 24 months of age when measurements of scrotal circumference, sheath score, semen mass activity, progressive motility of individual sperm and percent morphologically normal sperm were recorded. Magnitude of heritability and genetic correlations changed across time for some traits. Heritability of LH, inhibin, IGF-I and of 18-month scrotal circumference, mass activity, progressive motility and percent normal sperm was 0.31, 0.74, 0.44, 0.75, 0.24, 0.15 and 0.25, respectively, for Brahmans and 0.48, 0.72, 0.36, 0.43, 0.13, 0.15 and 0.20, respectively, for Tropical Composites. Inhibin and IGF-I had moderate genetic association with percent normal sperm at 24 months in Brahmans but low to negligible associations in Tropical Composites. Body condition score in Brahmans and sperm motility (mass and individual) traits in both genotypes had moderate to strong genetic correlation with percent normal sperm and may prove useful candidates for indirect selection. There is scope to increase scrotal circumference by selection and this will be associated with favourable correlated responses of improved semen quality in both genotypes. The lack of genetic antagonism among bull traits indicates that selection for improved semen quality will not adversely affect other production traits.

A highly effective and selective male lure for Bactrocera jarvisi (Tryon) (Diptera: Tephritidae)

Bactrocera jarvisi (Tryon) is a moderate pest fruit fly particularly in northern Australia where mango is its main commercial host. It was largely considered non-responsive to the known male lures. However, male B. jarvisi are attracted to the flowers of Bulbophyllum baileyi, Passiflora ligularis, Passiflora maliformis and Semecarpus australiensis and this paper describes an attempt to determine the attractive compounds in the latter two species through chemical analysis. At about the same time, zingerone was identified as a fruit fly attractant in the flowers of Bulbophyllum patens in Malaysia, and this led the author to speculate that it could be attracting B. jarvisi to the flowers of B. baileyi. Two long-term traps, each with lures containing 2 g of liquefied zingerone and 1 mL maldison EC were established at Speewah, west of Cairns, in November 2001 and retained until April 2007. Over five complete years, 68 897 flies were captured, of which 99.6% were male B. jarvisi. Annual peaks in activity occurred between mid-January and early February, when they averaged 1428.5 +/- 695.6 (mean +/- standard error) male B. jarvisi/trap/week. Very few B. jarvisi were caught between June and September. Among 12 other species of Bactrocera and Dacus attracted to zingerone were the previously non-lure responsive Bactrocera aglaiae, a new species Bactrocera speewahensis, and the rarely trapped Dacus secamoneae. Four separate trials were conducted over 8- to 19-week periods to compare the numbers and species of Bactrocera and Dacus caught by zingerone, raspberry ketone/cue-lure or methyl eugenol-baited traps. Overall, 27 different species of Bactrocera and Dacus were recorded. The zingerone-baited traps caught 97.799.3% male B. jarvisi and no methyl eugenol responsive flies. Significantly more Bactrocera neohumeralis or Bactrocera tryoni were attracted to raspberry ketone/cue-lure than to zingerone (P < 0.001). Zingerone and structurally related compounds should be tested more widely throughout the region.

Multi-trait assessment of early-in-life female, male and genomic measures for use in genetic selection to improve female reproductive performance of Brahman cattle

Early-in-life female and male measures with potential to be practical genetic indicators were chosen from earlier analyses and examined together with genomic measures for multi-trait use to improve female reproduction of Brahman cattle. Combinations of measures were evaluated on the genetic gains expected from selection of sires and dams for each of age at puberty (AGECL, i.e. first observation of a corpus luteum), lactation anoestrous interval in 3-year-old cows (LAI), and lifetime annual weaning rate (LAWR, i.e. the weaning rate of cows based on the number of annual matings they experienced over six possible matings). Selection was on an index of comparable records for each combination. Selection intensities were less than theoretically possible but assumed a concerted selection effort was able to be made across the Brahman breed. The results suggested that substantial genetic gains could be possible but need to be confirmed in other data. The estimated increase in LAWR in 10 years, for combinations without or with genomic measures, ranged from 8 to 12 calves weaned per 100 cows from selection of sires, and from 12 to 15 calves weaned per 100 cows from selection of sires and dams. Corresponding reductions in LAI were 60-103 days or 94-136 days, and those for AGECL were 95-125 or 141-176 days, respectively. Coat score (a measure of the sleekness or wooliness of the coat) and hip height in females, and preputial eversion and liveweight in males, were measures that may warrant wider recording for Brahman female reproduction genetic evaluation. Pregnancy-test outcomes from Matings 1 and 2 also should be recorded. Percentage normal sperm may be important to record for reducing LAI and scrotal size and serum insulin-like growth factor-I concentration in heifers at 18 months for reducing AGECL. Use of a genomic estimated breeding value (EBV) in combination with other measures added to genetic gains, especially at genomic EBV accuracies of 40%. Accuracies of genomic EBVs needed to approach 60% for the genomic EBV to be the most important contributor to gains in the combinations of measures studied.

Cucumber volatile blend, a promising female-biased lure for Bactrocera cucumis (French 1907) (Diptera: Tephritidae: Dacinae), a pest fruit fly that does not respond to male attractants

Bactrocera cucumis (French 1907), the ‘cucumber fruit fly’, is a horticultural pest in Australia that primarily infests cucurbits and has also been recorded from tomatoes, papaw and several other hosts. It does not respond to known male lures, cue-lure and methyl eugenol, making monitoring and control difficult. A cucumber volatile blend lure was recently developed in Hawaii and found to be an effective female-biased attractant for the melon fly B. cucurbitae. This lure was field tested in north Queensland, Australia in McPhail traps in comparison with orange ammonia, Cera Trap® and a control, and was found to more consistently trap B. cucumis than the other lures. B. cucumis were caught at 41% of the cucumber volatile lure trap clearances, compared with 27% of the orange ammonia, 18% of the Cera Trap and 16% of the control trap clearances. The cucumber volatile lure was more attractive to B. cucumis in low population densities and also trapped B. cucumis earlier on average than the other lures. Data analysed from the site with highest trap catches (Spring Creek) showed that the cucumber volatile lure caught significantly more B. cucumis than the other traps in four of the 11 trap clearance periods, and for the remaining clearances, no other trap type caught significantly more flies than the cucumber volatile lure. The cucumber volatile lure had a strong female-biased attraction but it was not significantly more female-biased than orange ammonia or Cera Trap. Cucumber volatile lure traps were cleaner to service resulting in better quality specimens than the orange ammonia trap or Cera Trap. These findings have potential implications for market access monitoring for determining pest freedom, and for biosecurity monitoring programmes in other countries that wish to detect B. cucumis early.

Sexual selection in true fruit flies (Diptera: Tephritidae): transcriptome and experimental evidences for phytochemicals increasing male competitive ability

In male tephritid fruit flies of the genus Bactrocera, feeding on secondary plant compounds (sensu lato male lures = methyl eugenol, raspberry ketone and zingerone) increases male mating success. Ingested male lures alter the male pheromonal blend, normally making it more attractive to females and this is considered the primary mechanism for the enhanced mating success. However, the male lures raspberry ketone and zingerone are known, across a diverse range of other organisms, to be involved in increasing energy metabolism. If this also occurs in Bactrocera, then this may represent an additional benefit to males as courtship is metabolically expensive and lure feeding may increase a fly's short-term energy. We tested this hypothesis by performing comparative RNA-seq analysis between zingerone-fed and unfed males of Bactrocera tryoni. We also carried out behavioural assays with zingerone- and cuelure-fed males to test whether they became more active. RNA-seq analysis revealed, in zingerone-fed flies, up-regulation of 3183 genes with homologues transcripts to those known to regulate intermale aggression, pheromone synthesis, mating and accessory gland proteins, along with significant enrichment of several energy metabolic pathways and gene ontology terms. Behavioural assays show significant increases in locomotor activity, weight reduction and successful mating after mounting; all direct/indirect measures of increased activity. These results suggest that feeding on lures leads to complex physiological changes, which result in more competitive males. These results do not negate the pheromone effect, but do strongly suggest that the phytochemical-induced sexual selection is governed by both female preference and male competitive mechanisms.

Cuelure but not zingerone make the sex pheromone of male Bactrocera tryoni (Tephritidae: Diptera) more attractive to females

In tephritid fruit flies of the genus Bactrocera Macquart, a group of plant derived compounds (sensu amplo ‘male lures’) enhance the mating success of males that have consumed them. For flies responding to the male lure methyl eugenol, this is due to the accumulation of chemicals derived from the male lure in the male rectal gland (site of pheromone synthesis) and the subsequent release of an attractive pheromone. Cuelure, raspberry ketone and zingerone are a second, related group of male lures to which many Bactrocera species respond. Raspberry ketone and cuelure are both known to accumulate in the rectal gland of males as raspberry ketone, but it is not known if the emitted male pheromone is subsequently altered in complexity or is more attractive to females. Using Bactrocera tryoni as our test insect, and cuelure and zingerone as our test chemicals, we assess: (i) lure accumulation in the rectal gland; (ii) if the lures are released exclusively in association with the male pheromone; and (iii) if the pheromone of lure-fed males is more attractive to females than the pheromone of lure-unfed males. As previously documented, we found cuelure was stored in its hydroxyl form of raspberry ketone, while zingerone was stored largely in an unaltered state. Small but consistent amounts of raspberry ketone and β-(4-hydroxy-3-methoxyphenyl)-propionic acid were also detected in zingerone-fed flies. Males released the ingested lures or their analogues, along with endogenous pheromone chemicals, only during the dusk courtship period. More females responded to squashed rectal glands extracted from flies fed on cuelure than to glands from control flies, while more females responded to the pheromone of calling cuelure-fed males than to control males. The response to zingerone treatments in both cases was not different from the control. The results show that male B. tryoni release ingested lures as part of their pheromone blend and, at least for cuelure, this attracts more females.

Responses of fruit flies (Tephritidae: Dacinae) to novel male attractants in north Queensland, Australia, and improved lures for some pest species

Male fruit fly attractants, cue-lure and methyl eugenol (ME), have been successfully used for the last 50 years in the monitoring and control of Dacini fruit flies (Bactrocera and Dacus species). However, over 50% of Dacini are non-responsive to either lure, including some pest species. A new lure, zingerone, has been found to weakly attract cue- and ME-responsive species in Malaysia. In Australia it attracted a weakly cue-responsive minor pest Bactrocera jarvisi (Tryon) and three non-responsive' species. Similar compounds were tested in Queensland and attracted cue- and ME-responsive species and two non-responsive' species. In this study, 14 novel compounds, including raspberry ketone formate (RKF) (Melolure) and zingerone, were field tested in comparison with cue-lure and ME at 17 sites in north Queensland. The most attractive novel lures were isoeugenol, methyl-isoeugenol, dihydroeugenol and zingerone. Several non-responsive' species responded to the new lures: Bactrocera halfordiae (Tryon), a species of some market access concern, was most attracted to isoeugenol; B.barringtoniae (Tryon), B.bidentata (May) and B.murrayi (Perkins) responded to isoeugenol, methyl-isoeugenol and dihydroeugenol; two new species of Dacus responded to zingerone. Bactrocera kraussi (Hardy), a cue-responsive minor pest in north Queensland, was significantly more attracted to isoeugenol than cue-lure. The cue-responsive D.absonifacies (May) and D.secamoneaeDrew were significantly more attracted to zingerone than cue-lure. Bactrocera yorkensisDrew & Hancock, a ME-responsive species was significantly more attracted to isoeugenol, methyl-isoeugenol and dihydroeugenol than ME. The preferential response to RKF or cue-lure was species specific. Six species were significantly more attracted to RKF, including the pests B.tryoni (Froggatt), B.frauenfeldi (Schiner) and minor pest B.bryoniae (Tryon); eight species were significantly more attracted to cue-lure including the pest B.neohumeralis (Hardy). These findings have significance in the search for optimal male lures for pest species elsewhere in the world.

Chemical containment and eradication of screw− worm incursions in Australia

Screwworms are obligate, invasive parasites of warm-blooded animals. The female flies lay batches of eggs at the edge of wounds or other lesions. These eggs hatch to larvae or screw-worms which feed on affected animals for 6-7 days, burrowing deeply into subcutaneous tissues and causing severe trauma to animals, production loss and potentially death. Susceptible sites include wounds resulting from management practices such as castration, de-horning and ear tagging and lesions caused by the activities of other parasites such as buffalo flies and ticks. The navels of the new born and the vulval region of their mothers following parturition are highly susceptible and body orifices such as nose and ears are also frequent targets for ovipositing screwworm flies. The Old World screw-worm, Chrysomya bezziana (OWS) is considered one of the most serious exotic insect pest threatening Australia's livestock industries and is endemic in a number of our closest neighbouring countries. New World screwworm (NWS), Cochliomyia hominivorax, endemic to South America, has also entered Australia on at least 2 occasions. Many tropical and subtropical areas of Australia are suitable for the establishment of OWS and the potential range is expected to increase with climate change. The Australian screwworm preparedness strategy indicates a program of containment with chemical treatments followed by eradication of OWS using sterile male release and parasiticides. However, there is no longer an operational OWS sterile insect screw-worm facility anywhere in the world and establishing a large scale production facility would most optimistically take at least 2 years. In the interim, containment would be almost totally dependent on the availability of effective chemical controls. A review of chemical formulations available for potential use against OWS in Australia found that currently only one chemical, ivermectin administered by subcutaneous injection (s.c.) is registered for use against OWS and that many of the chemicals previously shown to be effective against OWS were no longer registered for animal use in Australia.18 From this review a number of Australian-registered chemicals were recommended as a priority for testing against OWS. The Australian Pesticides and Veterinary Medicines Authority (APVMA) can issue an emergency use permit for use of pesticides if they are registered in Australia for other animal uses and shown to be effective against OWS. This project tested the therapeutic and prophylactic efficacy of chemicals with potential for use in the treatment and control of OWS.