Biology and host range of Ophiomyia camarae Spencer (Diptera: Agromyzidae), a potential biocontrol agent for Lantana spp. (Verbenaceae) in Australia

The life history and host range of the herringbone leaf-mining fly Ophiomyia camarae, a potential biological control agent for Lantana spp., were investigated. Eggs were deposited singly on the underside of leaves. Although several eggs can be laid on a single leaf and a maximum of three individual mines were seen on a single leaf, only one pupa per leaf ever developed. The generation time (egg to adult) was about 38 days. Females (mean 14 days) lived longer than males (mean 9 days) and produced about 61 mines. Oviposition and larval development occurred on all five lantana phenotypes tested. Eleven plant species representing six families were tested to determine the host range. Oviposition and larval development occurred on only lantana and another nonnative plant Lippia alba (Verbenaceae), with both species supporting populations over several generations. A CLIMEX model showed that most of the coastal areas of eastern Australia south to 30°16' S (Coffs Harbour) would be suitable for O. camarae. O. camarae was approved for release in Australia in October 2007 and mines have been observed on plants at numerous field sites along the coast following releases.

Rejection by pigs of mouldy grain containing deoxynivalenol

Weaner pigs on a farm near Beaudesert in south eastern Queensland refused to eat feed comprised largely of wheat and barley. Older pigs consumed small amounts and some prepubertal gilts subsequently displayed enlarged and reddened vulvas. Wheat, barley and triticale were grown on the farm during 1983, which was unusually and persistently wet. The wheat and triticale were harvested and stored for about 3 weeks with moisture contents above 14% before being fed. Samples of the wheat and triticale contained pale pink grains, which can indicate infection by the fungus Fusariurn grarninearurn Schw. On analysis 2 mycotoxins known to be produced by F. graminearurn were detected, deoxynivalenol (vomitoxin) which causes feed refusal and vomiting, and zearalenone which causes oestrogenic effects. Concentrations of deoxynivalenol in the wheat, triticale and barley were 34, 10, and <0.1 mg/kg respectively. Concentrations of zearalenone were 6.2, 2.8 and 0.1 mg/kg respectively. Subsequently, F. grarninearurn was isolated from grains and crop residues. Although the wet weather contributed to F. grarninearurn infection of the crops before harvest, most of the toxins probably developed during storage.

Non-destructive assessment of Arundo donax (Poaceae) leaf quality

Leaf carbon (C) content, leaf nitrogen (N) content, and C:N ratio are especially useful for understanding plant-herbivore interactions and may be important in developing control methods for the invasive riparian plant Arundo donax L. We measured C content, N content, C:N ratio, and chlorophyll index (SPAD 502 reading) for 768 leaves from A. donax collected over a five year period at several locations in California, Nevada, and Texas. Leaf N was more variable than leaf C, and thus we developed a linear regression equation for estimating A. donax leaf N from the leaf chlorophyll index (SPAD reading). When applied to two independent data sets, the equation (leaf N content % = -0.63 + 0.08 x SPAD) produced realistic estimates that matched seasonal and spatial trends reported from a natural A. donax population. Used in conjunction with the handheld SPAD 502 meter, the equation provides a rapid, non-destructive method for estimating A. donax leaf quality.

Biocontrol of Chromolaena odorata in Papua New Guinea

Chromolaena odorata (L.) King and Robinson (Asteraceae) is a significant agricultural weed in Papua New Guinea (PNG), affecting plantations, food gardens and grazing lands. It was the focus of a collaborative biocontrol program funded by the Australian Government between 1998 and 2007. Chromolaena was recorded at 680 sites in 13 provinces of PNG through surveys, field releases of biocontrol agents and feedback from public awareness programs. Three biocontrol agents, the moth Pareuchaetes pseudoinsulata Rego Barros (Lepidoptera: Arctiidae), the stemgalling fly Cecidochares connexa (Macquart) (Diptera: Tephritidae) and the leaf mining fly Calycomyza eupatorivora Spencer (Diptera: Agromyzidae), were introduced to control chromolaena. Cecidochares connexa was found to be the most effective of the agents introduced as it quickly established at over 300 sites where it was released and spread up to 100km in five years from some sites. Experimental field plots established to determine the impact of the agents on chromolaena, showed that the size of chromolaena infestations decreased with the presence of C. connexa. A survey was conducted to quantify the social and economic benefits of biocontrol of chromolaena to landholders. Chromolaena is considered to be under substantial/significant control in nine provinces in PNG, with about 50% of respondents stating that there is less than 50% of chromolaena remaining following the release of the gall fly. This has resulted in landholders spending less time clearing chromolaena and the re-establishment of small-scale subsistence farms and the regeneration of natural vegetation. Crop yield and income generated from the sale of agricultural produce have increased by at least 50% since chromolaena was brought under biocontrol. It is anticipated that the gall fly will continue to spread and control chromolaena in areas where it has not yet reached, thereby further reducing the impact of the weed in PNG.