The impact of wind on trees in Australian tropical savannas: lessons from Cyclone Monica

Abstract The role of tropical cyclones in structuring tropical rainforests has long been recognized in the Americas and northern Australia. However, their role in the dynamics of Australian savannas has received little attention compared with the effects of fire and drought. In April 2006, Tropical Cyclone Monica caused trees to be snapped or uprooted across a swath about 50 km wide and 130 km inland in northern Australia. The proportion of trees damaged was assessed using on‐ground surveys and interpretation of aerial photographs along the cyclone path and along several perpendicular transects. From these data, a relationship between the damage to trees and estimated maximum gust speed was developed. From knowledge of gust recurrence, curves were then derived describing the changes with distance inland in the average recurrence interval for tree windthrow events. These relationships were consistent with the historical record of tree damage in the northwest of the Northern Territory. It was concluded that windthrow has profound, but hitherto unrecognized implications for ecological processes such as tree dynamics and fluxes of carbon and water in Australian tropical savannas.     

Extensive chromosomal variation associated with taxon divergence and host specificity in the gall-inducing scale insect Apiomorpha munita (Schrader) (Hemiptera: Sternorrhyncha: Coccoidea: Eriococcidae)

Apiomorpha Rubsaamen (Hemiptera: Coccoidea: Eriococcidae) is one of the most chromosomally diverse of all animal genera. There is extensive karyotypic variation within many of the morphologically defined species, including A. munita (Schrader) which is here reported to have diploid chromosome counts ranging from 6 to more than 100. Each of the three morphologically defined subspecies of A. munita also displays considerable chromosomal variation: A. m. tereticornuta Gullan (2 n = 6, 8, 20, 22 or 24), A. m. malleensis Gullan (2 n = 6, 20, 22, 24 or 26), and A. m. munita (Schrader) (2 n = 54 or >100). Apiomorpha munita appears to occur only on eucalypts of the informal subgenus Symphyomyrtus , with each of the subspecies of A. munita restricted to discrete symphyomyrt sections. Several different karyotypic forms within each subspecies of A. munita appear to be restricted to only one or a few eucalypt species or series. The association between apparent host specificity and chromosomal rearrangements in A. munita suggests that both may be playing an active role in taxon divergence in Apiomorpha.     

Revisions of Rump Fat and Body Scoring Indices for Deer,Elk, and Moose

Abstract: Because they do not require sacrificing animals, body condition scores (BCS), thickness of rump fat (MAXFAT), and other similar predictors of body fat have advanced estimating nutritional condition of ungulates and their use has proliferated in North America in the last decade. However, initial testing of these predictors was too limited to assess their reliability among diverse habitats, ecotypes, subspecies, and populations across the continent. With data collected from mule deer (Odocoileus hemionus), elk (Cervus elaphus), and moose (Alces alces) during initial model development and data collected subsequently from free-ranging mule deer and elk herds across much of the western United States, we evaluated reliability across a broader range of conditions than were initially available. First, to more rigorously test reliability of the MAXFAT index, we evaluated its robustness across the 3 species, using an allometric scaling function to adjust for differences in animal size. We then evaluated MAXFAT, rump body condition score (rBCS), rLIVINDEX (an arithmetic combination of MAXFAT and rBCS), and our new allometrically scaled rump-fat thickness index using data from 815 free-ranging female Roosevelt and Rocky Mountain elk (C. e. roosevelti and C. e. nelsoni) from 19 populations encompassing 4 geographic regions and 250 free-ranging female mule deer from 7 populations and 2 regions. We tested for effects of subspecies, geographic region, and captive versus free-ranging existence. Rump-fat thickness, when scaled allometrically with body mass, was related to ingesta-free body fat over a 38–522-kg range of body mass (r² = 0.87; P < 0.001), indicating the technique is remarkably robust among at least the 3 cervid species of our analysis. However, we found an underscoring bias with the rBCS for elk that had >12% body fat. This bias translated into a difference between subspecies, because Rocky Mountain elk tended to be fatter than Roosevelt elk in our sample. Effects of observer error with the rBCS also existed for mule deer with moderate to high levels of body fat, and deer body size significantly affected accuracy of the MAXFAT predictor. Our analyses confirm robustness of the rump-fat index for these 3 species but highlight the potential for bias due to differences in body size and to observer error with BCS scoring. We present alternative LIVINDEX equations where potential bias from rBCS and bias due to body size are eliminated or reduced. These modifications improve the accuracy of estimating body fat for projects intended to monitor nutritional status of herds or to evaluate nutrition's influence on population demographics.     

Exposure to the neonicotinoid imidacloprid disrupts sex allocation cue use during superparasitism in the parasitoid wasp Nasonia vitripennis

1. Neonicotinoid insecticides are potent neurotoxins of significant economic importance. However, it is clear that their use can adversely impact beneficial insects in the environment, even at low, sub‐lethal doses. 2. It has recently been shown that the neonicotinoid imidacloprid disrupts adaptive sex allocation in the parasitoid wasp Nasonia vitripennis (Walker) by limiting their ability to respond to the presence of other females on oviposition patches. In the present study, that work was extended to explore whether sex allocation when superparasitising – laying eggs on a host that has already been parasitised – is also disrupted by imidacloprid. 3. Under superparasitism, sex allocation theory predicts that females should vary their offspring sex ratio in relation to their relative clutch size. It was found that sex allocation under superparasitism in Nasonia is disrupted in a dose‐dependent manner, with exposed females producing more daughters. 4. Importantly, imidacloprid does not appear to influence the ability of females to estimate the number of eggs already present on a host, suggesting a disassociation between the sex ratio and clutch size cues. 5. The present work highlights the fitness costs to beneficial insects of exposure to neonicotinoids, but also provides clues as to how female Nasonia use information when allocating sex.     

PEDAL AND OPERCULAR SECRETORY GLANDS OF POMATIAS, BITHYNIA AND LITTORINA

The histochemical properties of the pedal and opercular glandcells of three prosobranchs from different habitats were examined.The suprapedal gland of Pomatias elegans contained 3 gland celltypes producing mucoprotein, protein and sulphated muco-polysaccharide.The ventral surfaces of the foot were devoid of gland cellsexcept in the median furrow in which two cell types producea neutral and a sulphated mucopolysacharide. The dorsal surfaceof the foot possesses 5 cell types which produce a variety ofmucosubstances. The anterior pedal gland of Bithynia tentaculata produces neutraland weakly acidic mucoprotein from one cell type. The ventralsurface of the foot is generally populated by gland cells oftwo types producing acid mucopolysaccharide and protein. A furthercell type producing carboxylated mucopolysaccharide is restrictedto a transverse band mid-way down the foot. The dorsal surfaceof the foot is covered by mucus from three cell types producinga variety of mucosubstances. The anterior pedal gland of Littorina littorea possesses twocell types both of which secrete mucoprotein. The ventral surfaceof the foot secretes sulphated and carboxylated mucopolysaccharideand a mucoprotein from three cell types which form a thick subepi-dermalglandular layer. The dorsal surface is lubricated by a sulphatedmucopolysaccharide and a mucoprotein. The secretory cells of the dorsal surface extend into the operculargroove and disc whose specialised cells generally secrete mucopolysaccharideand at least two differently staining proteins. ^*Present address: Department of Zoology, University of Durham,Durham City, U.K. (Received 19 August 1986;