Responses of the weed parthenium hysterophorus (Asteraceae) to the stem Gall-inducing Weevil Conotrachelus albocinereus (Coleoptera: Curculionidae)
- Authors: Florentine, Singarayer , Westbrooke, Martin , Dhileepan, Kunjithapatham
- Date: 2002
- Type: Text , Journal article
- Relation: Entomologia Generalis Vol. 26, no. 3 (2002), p. 195-206
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- Description: A slem-galling weevil COT/o/rad,e/us alboeinereus Fiedler 1940 from Argentina is being field released to regulate populations of the weed Parlhenium hysterophorus in Queensland, Australia since 1995. In this paper we report the tissue and metabolic responses in P hyslerophorus in the context of the biology and feeding behaviour of the weevil. C albocinereus induces elliptical galls often on the main shoot axes and rarely on the terminal and axillary mcristems of the host plant. From oviposition through gall maturation, the structure and metabolism of the host-plant tissues. especially at the gall region, change continuously to accommodate pressure inflicted by the feeding larva. The host plant shows re-dirtttion of its vital metabolites to the gall, and to the lTlCtaplasitd cells of nutrition in particular. In mature galls. the pith parenchyma elements tum lignified. Larval feeding fractures the vertical continuity of vascular tissues, which affects the host plant's overall metabolism As the larva tunnels the shoot eolulTVl. it places the frass at the fissured vascular sites. That activity initialcs n«rosis and eventual death of the living eells of the vascular tissue complex. Such a development induces water.logging stress in the gall and the evapotranspirauonal system displays contrasting responses. Pennanenl1y closed Siomatal apertures and abnonnally inflated substomatal chambers indicate that P hYSleropltorus suffers moisture-stress with cecidogenesis. The larval performance triggers moisture inundation in the galled shoot and this appears to be an advantage in using this weevil in the control of P hyslerop/rorus.
- Description: C1
- Description: 2003004175
Multivariate statistical analysis of songs of the male Common Blackbird (Turdus merula) : An example from western Victoria, Australia
- Authors: Kentish, Barry , Harvey, Jack , Roberts, Lyn , Ross, Jason
- Date: 2001
- Type: Text , Journal article
- Relation: EMU Vol. 101, no. 4 (2001), p. 335-340
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- Description: Variation in the song of the male Common Blackbird was investigated within and between two locations in western Victoria. Each of 400 phrases (100 phrases per male) was characterised by 61 measurements relating to 13 aspects of each phrase. Principal component and stepwise discriminant analyses were undertaken on these measurements. Classification of blackbird song for location and individuality was based on timing within the phrase of the loudest elements. Evidence was found for within-phrase variability, with the greatest variation in the middle of the phrase. Within- and between-site comparison found that blackbird song exhibited both individual and site-specific characteristics consistent with earlier suggestions of phrase sharing within local populations. The study demonstrated that an objective statistical approach to song analysis was able to disciminate between individual birds from different locations.