Post‐breeding movements of Wood Storks in Brazil and Argentina

Seasonal migration and the dispersal of juvenile and adult Wood Storks (Mycteria americana) after breeding have been documented in the United States, but little is known about the post‐breeding movements of Wood Storks in South America. Our objective was to identify the locations of post‐breeding areas used by Wood Storks banded as nestlings in breeding colonies in Brazil by analyzing banding data. During the period from 1984 to 2007, 2543 nestlings were banded at breeding colonies in three regions of Brazil, with most (94%) banded in the Pantanal wetland in west‐central Brazil. Seventeen bands were subsequently recovered, with most (14) recovered in southern Brazil and northern Argentina. The mean distance between banding and recovery sites was 1265 km. Our results suggest that Wood Stork movements from breeding areas in Brazil are, as also reported in the United States, in response to changing water levels. The rainy season begins at the end of the breeding season and, in apparent response to rising water levels, Wood Storks in our study moved to drier areas further south with shallower water where they can forage more efficiently. Because only a small percentage of the area where Wood Stork bands were recovered in our study is currently protected, measures are needed to prevent habitat destruction and preserve wetland habitats used by Wood Storks during the post‐breeding period in southern Brazil and Argentina.     

Tarsal chemoreception in the polyphagous grasshopper Schistocerca americana: behavioural assays, sensilla distributions and electrophysiology

ABSTRACT Behavioural and electrophysiological responses of Schistocerca americana (Drury) (Orthoptera: Acrididae) to chemical stimulation of the tarsi were investigated. Using restrained insects, differences in leg-waving behaviour were observed following stimulation by sucrose and nicotine hydrogen tartrate (NHT), compared to control stimulations by water. Furthermore, free-walking insects were able to detect NHT on leaf surfaces, resulting in leg-raising to avoid tarsal contact.
SEM studies showed the presence of numerous peg chemoreceptor sensilla on the ventral surface of the tarsus. Tip recordings from such pegs showed activity from up to three chemosensitive neurones, plus a mechanoreceptor neurone. Stimulation by NaCl and KC1 elicited similar responses from two or three neurones in all sensilla tested, with increased firing rates at higher concentrations. Sucrose caused an increase in firing rate in few sensilla. In such cases several neurones were stimulated, and there was no evidence of a specific neurone sensitive to sucrose. In contrast, NHT elicited rapid firing in a single neurone, which was not sensitive to NaCl. Stimulation by NHT also inhibited the activity of the NaCl-sensitive neurones.
Possible mechanisms for chemical discrimination in S. americana tarsi are compared with those previously proposed for grasshopper mouthpart sensilla, and the significance of a NHT-sensitive neurone in tarsal sensilla is discussed.     

POTENTIAL OF DISCARIA AMERICANA FOR METAL STABILIZATION ON SOILS AMENDED WITH BIOSOLIDS AND ASH-SPIKED BIOSOLIDS

Biosolids (B) may contain various types of environmental pollutants, which can exert phytotoxic effects in plants. The effect of aqueous extracts on seed germination and the primary root growth of discaria (Discaria americana) obtained from different soil-application rates of B and a mixture of B and incinerated B were investigated. The objective was to evaluate the potential use of discaria for the stabilization of B-amended soils. Ryegrass (Lolium perenne L.) was used for comparison. Compared to ryegrass, relative seed germination (RSG) was significantly lower for discaria. RSG of discaria and rye grass was inversely correlated to the electrical conductivity of extracts, although a significant adverse effect was only observed for ryegrass with the highest dose of the mixture of B and incinerated B. This dose also produced a reduction in the germination index of discaria, which could not be correlated with the parameters studied. The B extracts did not exert any significant adverse effect on the relative root growth of both species. An increase in relative root growth and germination index was observed for discaria with a field application rate equivalent of 156 t DW ha^?1 of B, suggesting a stimulating effect of the amendment. The results obtained in this study suggest that germinated seedlings of discaria might be used for the stabilization of B-amended soils. However, further greenhouse and field experiments should be performed to confirm these findings.     

Phospholipid fatty acids from exocrine and reproductive tissues of male american cockroaches,Periplaneta americana (L.)

We present the phospholipid fatty acid compositions, determined by GLC,* of four individual tissues (testes, mushroom glands, conglobate glands, and salivary glands) from adult male cockroaches, P. americana. The testes phospholipids contained higher proportions of palmitic acid than did the exocrine tissues (16% vs about 8%). This was also true for palmitoleic (2.3% vs 0.4–1.3%), oleic (49% vs 30–35%), and linolenic acids (7% vs 0.5–2.8%). Testicular extracts were lower in linoleic acid (16%) than were the exocrine gland extracts (at 40–45%). All four tissues also contained low proportions of several long-chain polyunsaturated fatty acids of both omega-3 and omega-6 metabolic families, including C20:3n6, C20:4n6, and C20:5n3. The data suggest that the phospholipid fatty acid profiles of specific tissues differ from each other and from those obtained from whole-insect extracts. The presence of several polyenoics from the n3 and n6 metabolic families is interpreted in the context of complex fatty acid requirements at the tissue level.     

Habitat Selection by American Martens in Coastal California

ABSTRACT We investigated habitat selection using single- and mixed-scale modeling at 2 spatial scales, stand and home range, by the only known population of American martens (Martes americana) remaining in the historical range of the Humboldt subspecies (M. a. humboldtensis) in California, USA. During 2000 and 2001, we sampled a 12 times 14 grid with 2-km spacing, using 2 sooted track plates at each grid point. We detected martens at 26 of the 159 grid points. We used resource selection probability functions and an information-theoretic method to model habitat at detection locations. At the stand scale, martens selected conifer-dominated stands with dense, spatially extensive shrub cover (x̄ = 74% cover, SE = 4) in the oldest developmental stage. At the home-range scale, martens selected the largest available patches (x̄ = 181 ha, SE = 14) of old-growth, old-growth and late-mature, or serpentine habitat. Mixed-scale models revealed that habitat characteristics from both scales best explained marten occurrence compared to one scale alone. Dense, spatially extensive shrub cover is a key habitat element for martens in coastal forests. Dense shrubs provide refuge from predators, cover for prey, and may also deter larger-bodied competitors. Managers can increase the likelihood of marten population persistence and encourage expansion in coastal forests by maintaining and restoring late-mature and old-growth, conifer-dominated forests with dense shrub cover in large, contiguous patches.     

Risk assessment of Hass avocado and Mexican Lauraceae for attack by redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae)

1. The redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), vectors the mycopathogen that causes laurel wilt, a lethal vascular disease of trees in the Lauraceae. Since being detected in Georgia, USA in 2002, this invasive pest has become established in 11 additional states.
2. With continued spread, X. glabratus will likely enter Mexico. In advance of this event, this study was initiated to assess the risk posed to eight native laurels and Hass avocados, the predominant cultivar grown in Mexico.
3. Wood bolts from each species were used in (a) field tests to determine the relative attraction of female X. glabratus, (b) laboratory bioassays to evaluate boring preferences, and (c) GC–MS analyses to identify host kairomones. For comparison, tests included control bolt treatments consisting of silkbay (an attractive U.S. laurel) and Simmonds avocado (a Florida cultivar susceptible to laurel wilt).
4. Hass avocado and two native laurels (Persea schiedeana and Ocotea heribertoi vel aff.) were highly attractive to females and elicited strong boring responses. These species were high in sesquiterpene hydrocarbons, including α-copaene and α-cubebene.
5. Results of this study suggest that X. glabratus could become a serious agricultural and forest pest upon incursion into Mexico, with severe economic and ecological impacts.

     

Structure–function studies on hypertrehalosaemic and adipokinetic hormones: activity of naturally occurring analogues and some N- and C-terminal modified analogues

Abstract The relative potencies, with respect to mobilization of lipids in Locusta migratoria L. and in Schistocerca gregaria Forsk. and of carbohydrates in Periplaneta americana L., of eleven naturally-occurring members of the AKH/RPCH-family of peptides and of some analogues that lacked the N-terminal pyroglutamate residue or had a free threonine acid at the C-terminus instead of an amide are assessed. The time courses for carbohydrate and lipid release shown for the peptides suggest that their transport and degradation rates are similar. Therefore, their relative activities reflect most probably the different abilities to bind to the receptors on the fat body cells of the cockroaches and locusts tested. The results show clearly that the N- and C-terminally modified analogues give poor or almost no responses regardless of the bioassay employed. Compared with the structural requirements of the cockroach receptor(s), the receptor(s) of the locusts appear more specific. In the cockroach bioassay, only the two octapeptides Lom-AKH-II and Grb-AKH, both lacking a proline residue at position 6, have high ED₅₀ values, whereas the ED₅₀ values of all other peptides are between 0.4 and 2.7 pmol. The exception is the nonapeptide Mas-AKH, lacking proline and having a serine residue at position 7 (a unique feature compared with the other peptides): no activity is exerted below 100 pmol and only a poor response is elicited with higher dosages. The L. migratoria receptor(s) bind the decapeptides best (exception: Bld-HrTH). Octapeptides, even Scg-AKH-II and Grb-AKH which lack a proline residue, elicit a maximum response, but ED₅₀ values are 7–15-fold higher than with Lom-AKH-I. Lom-AKH-II, however, gives only a truncated response. The nonapeptide Mas-AKH is able to elicit a maximum response, but 50 pmol are needed instead of 2 pmol (Lom-AKH-I). In 5.gregaria a maximum response is achieved with Lom-AKH-I and Grb-AKH, but injections of Scg-AKH-II, Lom-AKH-II and Rom-CC-I result in only truncated responses. The importance of a β-turn in the molecules and the presence of proline is discussed. No evidence is found for an antagonistic effect on binding of those peptides that fail to achieve maximum responses.