Satiation and the functional response: a test of a new model

Abstract. 1. A model of the functional response to prey density is derived to include the reduction in time available for search, T_s , resulting from predator satiation.
2. For larger prey items predator satiation occurs at each prey capture and T_s is reduced by the attack time and digestive pause of a series of attack cycles. For small prey items predator foraging is continuous at low densities with T_s reduced solely by attack time. At higher densities predator satiation occurs after the capture of several small prey items and T_s is reduced by the attack time and digestive pause of a series of foraging cycles.
3. A comparison of the predicted asymptotic level of prey capture using experimentally estimated parameter values, with the maximum consumption of aphids by larval and adult coccinellids provides a test of the satiation model.
4. The limitation of prey capture by predator satiation is discussed with reference to handling time and the success of coccinellids in biological control.     

Geographic variation in jungle cat (Felis chaus Schreber, 1777) (Mammalia,Carnivora, Felidae) body size: is competition responsible?

There is a striking difference in body size of jungle cats ( Felis chaus ) in the west and the east of their distribution, with Israeli cats being 43% heavier than Indian cats. We tested the hypothesis that increasing competition from other small felids towards the east is responsible for the difference in body size. We measured jungle cat skulls for eight cranial and dental variables and related these to independent variables such as species richness (local and regional), latitude, longitude, temperature, and precipitation. Data from a narrow band between latitudes 24.0°N and 33.9°N, where Bergmann's rule was largely not observed, showed that the western population (≤ 50.0°E longitude) of jungle cats is larger than the eastern (> 60.0°E longitude) population with the size difference being most evident in the upper carnassials (P⁴L). Species richness at the regional level showed a significant negative relation to P⁴L. An even spacing in condylobasal length for a small-cat guild from India through null model analysis indicated the occurrence of character displacement. The results support the hypothesis that competition is responsible for geographical variation in jungle cat body size in the region where Bergmann's rule does not apply. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 163–172.     

Post-harvest age-induced seed dormancy of Acer ginnala and its alleviation by growth regulator and low temperature treatments

One-month-old fruits of Acer ginnala with winged pericarp attached gave 44% germination and this was not increased by cold treatment at 4°C for 0, 10, 20, or 30 days, gibberellic acid treatment at 0, 1, 10, 100 or 1000 mg litre^-1, or ethephon treatment at 0, 2, 20, 200 or 2000 mg litre^-1. After 6 months of storage at 20–25 °C, germination of untreated fruits fell to 5% but could be restored to that of 1-month-old fruits by incubation at 4 °C for 30 days. After 9 months storage, no germination occurred in untreated fruits. Cold treatment (30 days at 4 °C partially restored germination (26%). Treatment with either gibberellic acid (1000 mg litre^-1) and 30 days at 4 °C (40%) or ethephon (100 mg litre^-] and 30 days at 4 °C improved germination (69%). The combination of all three treatments, i.e. 100 mg litre^-1 gibberellic acid, 100 mg litre^-1 ethephon and 30 days at 4 °C, optimised germination (86%). Thus, dormancy of A. ginnala developed during storage but could be reversed by a combination of treatment with low temperature and growth regulators. The highest germination (86%) was achieved after low temperature and growth regulator treatment of stored fruit.     

Microbial enzyme activities as indicators of organic matter processing rates in a Lake Erie coastal wetland

1. Particulate organic material (POM) is an important source of energy and nutrients in aquatic ecosystems. The decomposition of this material is typically studied using the litter bag technique. However, this method has inherent limitations that can preclude the estimation of in situ decomposition rates, especially for fine particles. In this study, we tried to circumvent these limitations through the use of enzymatic decomposition models (EDMs), which relate mass loss rates to lignocellulase activities. With this approach, we investigated the in situ processing of three size ranges of detritus in a Typha wetland. 2. Litter was collected, dried and sorted into three size ranges [coarse (C) > 4, medium (M) 0.5–4 and fine (F) 0.063–0.5 mm] and placed in litter bags that were attached to the sediment surface at two sites in a Typha wetland in May 1994. Over a 7-month period, litter bags were collected and analysed for mass loss and the activities of six extracellular enzymes involved in the degradation of lignocellulose. In situ POM was collected concurrently, sorted into the same three size ranges and assayed for the same suite of enzymes. Additional cores were taken for the determination of organic matter standing stocks and particle size distribution. 3. Mean mass loss rates for CPOM, MPOM and FPOM were -0.139, -0.073 and -0.053% day^?1, respectively. Only CPOM rates were significantly different between sites. For CPOM and FPOM there were strong linear relationships between mass loss and cumulative enzyme activities; the mass loss data for MPOM were erratic and precluded the development of reliable enzyme models. EDMs for CPOM and FPOM were constructed from regressions relating mass loss to average cumulative lignocellulase activity, and used to estimate instantaneous in situ decomposition rates. These rates varied by site and throughout the year but averaged -0.204 and -0.045% day^?1, respectively. Based upon measurements of OM standing stock and particle size distributions, POM processing rates of 1100–1400 g m² yr^?1 were calculated. These rates are near the upper end of the range for net annual production in Typha wetlands, suggesting that there is little net accumulation of POM. 4. Despite some problems, the EDM method has the potential to facilitate studies of detrital dynamics in large, heterogeneous systems.     

Taxonomy of wild pigs (Sus) of the Philippines

Native wild pigs of the Philippines are now in grave danger of extinction. Study of available material indicates that three species are present: Sundaland Sus barbatus on Palawan, and two endemic species, Sus philippensis (with three subspecies, one of them here described as new) on Luzon, Mindanao, Basilan, Leyte, Samar, Catanduanes and Mindoro, and Sus cebifroms on Negros, debit and Panay. Specimens from Jolo. Masbale and Bohol presently remain unallocated to species, and may reflect the occurrence of hybridization.     

A MINIATURIZED ENRICHMENT SEROLOGY METHOD FOR RAPID DETECTION of SALMONELLA FROM POULTRY MEAT and REARING FARMS ENVIRONMENT

A miniaturization of the enrichment serology method for the detection of Salmonella was improved in order to make the technique more reliable, cheaper, and faster. the miniaturized method ("Micromethod") was compared to the Sperber and Deibel's method ("Macromethod") and with a classical isolation method; 1062 samples including 700 rearing farms environment samples, 247 poultry meat samples, and 115 nonfat dry milk samples were analyzed. Specificity of both enrichment serology methods was about 92–99.4%. Sensitivity of Micromethod was better than that of the Macromethod for the environmental samples (86.8 and 74.1%, respectively) and the poultry meat samples (87.5 and 77.5%, respectively) but was the same for the nonfat dry milk samples (82.5%). the costs of both methods were respectively 0.43 US $ for the Macromethod and 0.20 US $ for the Micromethod. This "Micromethod" could be proposed for the screening of Salmonella positive batches in the food industries.