The host range and biology of Cometaster pyrula; a biocontrol agent for Acacia nilotica subsp. indica in Australia

Prickly acacia, Acacia nilotica subsp. indica (Benth.) Brenan, a major weed of the Mitchell Grass Downs of northern Queensland, Australia, has been the target of biological control projects since the 1980s. The leaf-feeding caterpillar Cometaster pyrula (Hopffer) was collected from Acacia nilotica subsp. kraussiana (Benth.) Brenan during surveys in South Africa to find suitable biological control agents, recognised as a potential agent, and shipped into a quarantine facility in Australia. Cometaster pyrula has a life cycle of approximately 2 months during which time the larvae feed voraciously and reach 6 cm in length. Female moths oviposit a mean of 339 eggs. When presented with cut foliage of 77 plant species, unfed neonates survived for 7 days on only Acacia nilotica subsp. indica and Acacia nilotica subsp. kraussiana. When unfed neonates were placed on potted plants of 14 plant species, all larvae except those on Acacia nilotica subsp. indica and Acacia nilotica subsp. kraussiana died within 10 days of placement. Cometaster pyrula was considered to be highly host specific and safe to release in Australia. Permission to release C. pyrula in Australia was obtained and the insect was first released in north Queensland in October 2004. The ecoclimatic model CLIMEX indicated that coastal Queensland was climatically suitable for this insect but that inland areas were only marginally suitable.

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.

Studies on the rust Prospodium tuberculatum, a new classical biological control agent released against the invasive alien weed Lantana camara in Australia. 2. Host range

A strain of the rust Prospodium tuberculatum from Brazil was screened as a potential biocontrol agent against 40 Australian Lantana camara forms and 52 closely related, non-target plant species. Results under glasshouse conditions showed that the Brazilian rust strain is pathogenic to only two flower colour forms: pink and pink-edged red. Macro- and microsymptoms were recorded using 11 assessment categories and four susceptibility ratings. No macrosymptoms were observed on any of the non-target plants.

The infectivity and host range of Orgyia anartoides nucleopolyhedrovirus.

The painted apple moth (PAM), Teia anartoides (Walker) (Lepidoptera: Lymantriidae) made a recent incursion into New Zealand. A nucleopolyhedrovirus (NPV), Orgyia anartoides NPV (OranNPV), originally isolated from PAM in Australia, was tested for its pathogenicity to PAM and a range of non-target insect species found in New Zealand, to evaluate its suitability as a microbial control for this insect invader. Dosage-mortality tests showed that OranNPV was highly pathogenic to PAM larvae; mean LT50 values for third instars ranged from 17.9 to 8.1 days for doses from 102 to 105 polyhedral inclusion bodies/larva, respectively. The cause of death in infected insects was confirmed as OranNPV. Molecular analysis established that OranNPV can be identified by PCR and restriction digestion, and this process complemented microscopic examination of infected larvae. No lymantriid species occur in New Zealand; however, the virus had no significant effects on species from five other lepidopteran families (Noctuidae, Tortricidae, Geometridae, Nymphalidae and Plutellidae) or on adult honeybees. Thus, all indications from this initial investigation are that OranNPV would be an important tool in the control of PAM in a future incursion of this species into New Zealand.

Austropleospora osteospermi gen. et sp nov and its host specificity and distribution on Chrysanthemoides monilifera ssp rotundata in Australia.

Hendersonia osteospermi was found for the first time in Australia on leaf spots of the introduced invasive plant Chrysanthemoides monilifera ssp. rotundata (bitou bush) in coastal regions of New South Wales. Pathogenicity tests on species from 11 tribes in the family Asteraceae, demonstrated that H. osteospermi caused severe necrosis on leaves and stems of C. monilifera ssp. rotundata and its congener C. monilifera ssp. monilifera (boneseed). Small necrotic spots also developed on Osteospermum fruticosum and Dimorphotheca cuneata in the Calenduleae and on Helianthus annuus (sunflower) in the Heliantheae. None of the other plant species tested developed leaf spots, although H. osteospermi was re-isolated from senescent leaves of Cynara scolymus (globe artichoke) in the Cynareae and Vernonia cinerea in the Vernonieae. Single ascospores from ascomata of a Pleospora-like fungus found on diseased stems of bitou bush produced H. osteospermi in culture, which proved the anamorph/teleomorph connection. The ITS region of both a single-ascospore isolate and a single-conidium isolate were sequenced and found to be identical. The taxonomic status of H. osteospermi is re-examined and Austropleospora osteospermi gen. et sp. nov. is described as its teleomorph based on morphology, host range tests and DNA sequence analysis. The potential of A. osteospermi for the biological control of bitou bush and boneseed in Australia is discussed.

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.

Synthesis, Binding and Bioactivity of [gamma]-Methylene [gamma]-Lactam Ecdysone Receptor Ligands: Advantages of QSAR Models for Flexible Receptors

Nuclear hormone receptors, such as the ecdysone receptor, often display a large amount of induced fit to ligands. The size and shape of the binding pocket in the EcR subunit changes markedly on ligand binding, making modelling methods such as docking extremely challenging. It is, however, possible to generate excellent 3D QSAR models for a given type of ligand, suggesting that the receptor adopts a relatively restricted number of binding site configurations or [`]attractors'. We describe the synthesis, in vitro binding and selected in vivo toxicity data for [gamma]-methylene [gamma]-lactams, a new class of high-affinity ligands for ecdysone receptors from Bovicola ovis (Phthiraptera) and Lucilia cuprina (Diptera). The results of a 3D QSAR study of the binding of methylene lactams to recombinant ecdysone receptor protein suggest that this class of ligands is indeed recognized by a single conformation of the EcR binding pocket.

Critically endangered Pristis microdon (Elasmobranchii), as a host for the Indian parasitic copepod, Caligus furcisetifer Redkar, Rangnekar et Murti, 1949 (Siphonostomatoida): New records from northern Australia.

This paper presents the first records of the parasitic copepod Caligus furcisetifer Redkar, Rangnekar et Murti, 1949 beyond Indian waters, specifically, on the body surface and head of the critically endangered largetooth sawfish (commonly referred to as the freshwater sawfish in Australia), Pristis microdon Latham, 1794 (Elasmobranchii, Pristidae), in brackish tidal waters of the Fitzroy River in the Kimberley region of Western Australia and the Leichhardt River in the Gulf of Carpentaria in northern Queensland. This represents a geographic range extension of similar to 8000 km for this parasite. Further, it is only the second member of the genus Caligus to be found on an elasmobranch host in Western Australia and it is the first time this species has been reported from the Southern Hemisphere. Male biased dispersal of P microdon may be the vector in which the parasite has dispersed from India across to northern Australia, or vice versa. A decline in populations of the critically endangered P microdon (and possibly other pristid species) in these regions may lead to a concomitant decline in their parasite fauna.

Relative host plant species use by the lantana biological control agent Aconophora compressa (Membracidae) across its native and introduced ranges

Aconophora compressa Walker (Hemiptera: Membracidae) was released in 1995 against the weed lantana in Australia, and is now found on multiple host plant species. The intensity and regularity at which A. compressa uses different host species was quantified in its introduced Australian range and also its native Mexican range. In Australia, host plants fell into three statistically defined categories, as indicated by the relative rates and intensities at which they were used in the field. Fiddlewood (Citharexylum spinosum L.: Verbenaceae) was used much more regularly and at higher densities than any other host sampled, and alone made up the first group. The second group, lantana (Lantana camara L.: Verbenaceae; pink variety) and geisha girl (Duranta erecta L.: Verbenaceae), were used less regularly and at much lower densities than fiddlewood. The third group, Sheena’s gold (another variety of D. erecta), jacaranda (Jacaranda mimosifolia D. Don: Bignoniaceae) and myoporum (Myoporum acuminatum R. Br.: Myoporaceae), were used infrequently and at even lower densities. In Mexico, the insect was found at relatively low densities on all hosts relative to those in Australia. Densities were highest on L. urticifolia, D. erecta and Tecoma stans (L.) Juss. ex Kunth (Bignoniaceae), which were used at similar rates to one another. It was found also on a few other verbenaceous and non-verbenaceous host species but at even lower densities. The relative rate at which Citharexylum spp. and L. urticifolia were used could not be assessed in Mexico because A. compressa was found on only one plant of each species in areas where these host species co-occurred. The low rate at which A. compressa occurred on fiddlewood in Mexico is likely to be an artefact of the short-term nature of the surveys or differences in the suites of Citharexylum and Lantana species available there. These results provide further incentive to insist on structured and quantified surveys of non-target host use in the native range of potential biological control agents prior to host testing studies in quarantine.

Fruit fly host status testing of a new passionfruit cultivar

Fruit fly host status testing of a new passionfruit cultivar.

Life history and host range of Alagoasa extrema (Coleoptera: Chrysomelidae: Alticinae), a potential biological control agent of Lantana spp. (Verbenaceae) in Australia

The life history and host range of the lantana beetle, Alagoasa extrema, a potential biocontrol agent for Lantana spp. were investigated in a quarantine unit at the Alan Fletcher Research Station, Brisbane, Australia. Adults feed on leaves and females lay batches of about 17 eggs on the soil surface around the stems of plants. The eggs take 16 days to hatch and newly emerged larvae move up the stem to feed on young leaves. Larvae feed for about 23 days and there are three instars. There is a prepupal non-feeding stage that lasts about 12 days and the pupal stage, which occurs in a cocoon in the soil, lasts 16 days. Teneral adults remain in the cocoon for 3 days to harden prior to emergence. Males live for about 151 days while females live for about 127 days. The pre-oviposition period is 19 days. In no-choice larval feeding trials, nine plant species, representing three families, supported development to adult. Three species, Aloysia triphylla, Citharexylum spinosum and Pandorea pandorana were able to support at least two successive generations. These results confirm those reported in South Africa and suggest that A. extrema is not sufficiently specific for release in Australia. Furthermore, it is not recommended for release in any other country which is considering biological control of lantana.

Multiple host use by a sap-sucking membracid: population consequences of nymphal development on primary and secondary host plant species

Aconophora compressa is a gregarious, sap-sucking insect that uses multiple host plant species. Nymphal host plant species (and variety) significantly affected nymphal survival, nymphal development rate and the subsequent size and fecundity of adults, with fiddlewood ( Citharexylum spinosum ) being significantly best in all respects. Nymphs that developed on a relatively poor host ( Duranta erecta var “geisha girl”) and which were moved to fiddlewood as adults laid significantly fewer eggs (mean ± SE = 836 ± 130) than those that developed solely on fiddlewood (1,329 ± 105). Adults on geisha girl, regardless of having been reared as nymphs on fiddlewood or geisha girl, laid significantly fewer eggs (342 ± 83 and 317 ± 74, respectively) than adults on fiddlewood. A simple model that incorporates host plant related survival, development rate and fecundity suggests that the population dynamics of A. compressa are governed mainly by fiddlewood, the primary host. The results have general implications for understanding the population dynamics of herbivores that use multiple host plant species, and also for the way in which weed biological control host testing methods should be conducted.

Binding of polyphenols to plant cell wall analogues - Part 1: Anthocyanins

Anthocyanins are located within the vacuole of plant cells, and are released following cell rupture during eating or processing at which time they first come into contact with the plant cell wall. The extent of anthocyanin-cell wall interaction was investigated by monitoring the rate of anthocyanin depletion in the presence of pure cellulose or cellulose-pectin composites as cell wall models. It was found that anthocyanins interact with both cellulose and pectin over a two-stage process with initially (mins-hours) 13 similar to 18% of anthocyanins binding to cellulose or cellulose/pectincomposites. With prolonged exposure (days-weeks), a gradual increase in anthocyanin binding occurs, possibly due to anthocyanins stacking on top of a base layer. Binding of acylated and non-acylated anthocyanins followed a similar pattern with slightly more (5-10%) binding of the acylated forms. Composites with the highest pectin content had the greatest anthocyanin binding suggesting the existence of both ionic interactions (with pectin) and hydrophobic interactions (with cellulose) of anthocyanin with plant cell walls.

Host plant records for fruit flies (Diptera: Tephritidae) in Southeast Asia

Plant records, derived largely from field studies in Thailand and Malaysia from 1986-94, are provided for 131 species of Southeast Asian Tephritidae.