On the occurrence of Hippocampus fuscus in the eastern Mediterranean

The western Indian Ocean seahorse Hippocampus fuscus is recorded for the first time in the Mediterranean. Its presence there is probably due to migration from the Red Sea via the Suez Canal.     

Determining an economic injury level for the persea mite,Oligonychus perseae,a new pest of avocado in Israel

The persea mite, Oligonychus perseae Tuttle, Baker & Abbatiello (Acari: Tetranychidae), a pest of avocado, was first discovered in Israel in the autumn of 2001. It has since spread to most avocado growing areas in Israel. To establish an economic injury level (EIL), based on the percentage of leaf area damaged (PLAD), we conducted an extensive field study. For three consecutive seasons we created distinct pest infestation levels on the Hass avocado cv., by applying acaricides (spirodiclofen and abamectin) at 50, 100, and 250 mites per leaf levels, along with non‐sprayed controls in a replicated block design. At harvest time we evaluated the level of leaf damage and fruit yields across treatments. In two out of the 3 years, trees sprayed at 50 and 100 mites per leaf levels had similar PLAD values, differing from trees treated at the 250 mites per leaf level and the non‐treated control, the latter pair also being similar. Over the 3 years, mean yield attained at the two higher infestation levels was reduced by 20% in comparison to the mean yields recorded for plots sprayed at the lower thresholds. Accordingly, we suggest that scouts adopt an action threshold (AT) of 50–100 mites per leaf. Future research is needed to refine this AT. Mean annual cumulative mite days (CMDs) of the two higher levels was ca. 13500 ± 700 per leaf. Using the linear regression equation PLAD = 0.0009CMDs + 2.42, describing leaf damage as a function of CMDs, we estimated an EIL of ca. 15 PLAD.     

The Spines of the Channel Catfish, Ictalurus punctatus, as an Anti-Predator Adaptation: an Experimental Study

Although experimental evidence is lacking, the stout pectoral spine of catfishes has been interpreted as a defensive adaptation. The spine can be rigidly locked and abducted to produce stridulation sounds, which have been hypothesized to serve a warning function. We studied spine function in channel catfish (Ictalurus punctatus) as a deterrent to predation by largemouth bass (Micropterus salmoides) by presenting individuals with pairs of catfish, one with its pectoral spines clipped and the other intact. The number of initial attacks on clipped and intact fish was similar, suggesting that bass do not recognize the spine visually. Bass showed evidence of learning across trials, striking clipped fish fewer times and consuming them. Conversely, intact fish were attacked more than clipped ones because intact fish were repeatedly disgorged and attacked again, suggesting that bass become sensitized to the spine. Ingestion times were longer for intact than clipped fish, and fewer intact fish were eaten. Eighty‐eight percent of intact fish survived in the mouth of a bass one or more times. Catfish did not stridulate or use their spines to deter initial attacks, refuting the warning hypothesis. Locking and stridulation motions, only observed when catfish were held inside the mouth of a bass, did not deter subsequent attacks indicating that neither the spine nor stridulation carry a warning function. It is possible, therefore, that stridulation sounds function as a distress call. The spine functions against a gape‐limited predator by increasing the difficulty of ingestion but not capture.     

The importance of environmental heterogeneity and spatial distance in generating phylogeographic structure in edaphic specialist and generalist tree species of Protium (Burseraceae) across the Amazon Basin

Aim Edaphic heterogeneity may be an important driver of population differentiation in the Amazon but remains to be investigated in trees. We compared the phylogeographic structure across the geographic distribution of two Protium (Burseraceae) species with different degrees of edaphic specialization: Protium alvarezianum, an edaphic specialist of white‐sand habitat islands; and Protium subserratum, an edaphic generalist found in white sand as well as in more widespread soil types. We predicted that in the edaphic specialist, geographic distance would structure populations more strongly than in the edaphic generalist, and that soil type would not structure populations in the edaphic generalist unless habitat acts as a barrier promoting population differentiation. Location Tropical rain forests of the Peruvian and Brazilian Amazon, Guyana and French Guiana. Methods We sequenced 1209–1211 bp of non‐coding nuclear ribosomal DNA (internal transcribed spacer and external transcribed spacer) and a neutral low‐copy nuclear gene (phytochrome C) from P. subserratum (n = 65, 10 populations) and P. alvarezianum (n = 19, three populations). We conducted a Bayesian phylogenetic analysis, constructed maximum parsimony haplotype networks and assessed population differentiation among groups (soil type or geographic locality) using analysis of molecular variance and spatial analysis of molecular variance. Results The edaphic specialist exhibited considerable genetic differentiation among geographically distant populations. The edaphic generalist showed significant genetic differentiation between the Guianan and Amazon Basin populations. Within Peru, soil type and not geographic distance explained most of the variation among populations. Non‐white‐sand populations in Peru exhibited lower haplotype/nucleotide diversity than white‐sand populations, were each other’s close relatives, and formed an unresolved clade derived from within the white‐sand populations. Main conclusions Geographic distance is a stronger driver of population differentiation in the edaphic specialist than in the generalist. However, this difference did not appear to be related to edaphic generalism per se as adjacent populations from both soil types in the edaphic generalist did not share many haplotypes. Populations of the edaphic generalist in white‐sand habitats exhibited high haplotype diversity and shared haplotypes with distant white‐sand habitat islands, indicating that they have either efficient long‐distance dispersal and/or larger ancestral effective population sizes and thus retain ancestral polymorphisms. These results highlight the importance of edaphic heterogeneity in promoting population differentiation in tropical trees.     

Seroprevalence of Helicobacter pylori and Length of Stay in a Nursing Home

Background. Helicobacter pylori infection appears to be contracted mainly in childhood, and it is associated with disadvantaged socioeconomic conditions, overcrowding, and living in institutions. In this study we determined the seroprevalence of H. pylori among elderly patients (age ≥ 70 years) admitted to a major medical center in Israel, and studied the relationship between seroprevalence of H. pylori and the duration of stay in a nursing home prior to the admission.
Patients and Methods. Whole blood from 182 consecutive patients hospitalized at the Rabin Medical Center was tested for the presence of anti- H. pylori IgG using Helisal Rapid Blood Test kit (Cortecs Diagnostics). Multivariate logistic regression analysis was used to study the relation between H. pylori seropositivity and possible predictive factors such as age, gender and duration of stay in a nursing home.
Results. Of the 182 patients included in the study, 80 (44%) were living in nursing homes (NH) and 102 (56%) were living in their own homes (H) prior to admission. Subjects that stayed in nursing homes for more than 15 months were significantly more likely to be seropositive than subjects with a shorter duration of stay (84% and 63% respectively, p = 0.03). Using a multivariate logistic regression analysis on both the NH group and the whole group, seropositivity was found to be significantly associated with duration of stay in a nursing home (  p = 0.03 and p = 0.01 respectively). Seropositivity was not associated with age in either group.
Conclusions. Living in a nursing home is associated with increased risk for H. pylori infection in the elderly. There is a strong correlation between the duration of stay in a nursing home and the prevalence of H. pylori infection.     

Rapid shifts in <Emphasis Type=Italic>Atta cephalotes</Emphasis> fungus-garden enzyme activity after a change in fungal substrate (Attini,Formicidae)

Fungus gardens of the basidiomycete Leucocoprinus gongylophorus sustain large colonies of leaf-cutting ants by degrading the plant material collected by the ants. Recent studies have shown that enzyme activity in these gardens is primarily targeted toward starch, proteins and the pectin matrix associated with cell walls, rather than toward structural cell wall components such as cellulose and hemicelluloses. Substrate constituents are also known to be sequentially degraded in different sections of the fungus garden. To test the plasticity in the extracellular expression of fungus-garden enzymes, we measured the changes in enzyme activity after a controlled shift in fungal substrate offered to six laboratory colonies of Atta cephalotes. An ant diet consisting exclusively of grains of parboiled rice rapidly increased the activity of endo-proteinases and some of the pectinases attacking the backbone structure of pectin molecules, relative to a pure diet of bramble leaves, and this happened predominantly in the most recently established top sections of fungus gardens. However, fungus-garden amylase activity did not significantly increase despite the substantial increase in starch availability from the rice diet, relative to the leaf diet controls. Enzyme activity in the older, bottom sections of fungus gardens decreased, indicating a faster processing of the rice substrate compared to the leaf diet. These results suggest that leaf-cutting ant fungus gardens can rapidly adjust enzyme activity to provide a better match with substrate availability and that excess starch that is not protected by cell walls may be digested by the ants rather than by the fungus-garden symbiont.