Samy Zalat

Windows of opportunity and the temporal structuring of foraging activity in a desert solitary bee

1. Females of the desert solitary bee Anthophora pauperata collect nectar and pollen almost exclusively from Alkanna orientalis (Boraginaceae). The bee and plant are found together in the early spring, living in the bottom of steep‐sided wadis (dry river valleys) at an altitude of 1500 m in Egyptian Sinai.

Variation in the helminth community structure in spiny mice (Acomys dimidiatus) from four montane wadis in the St Katherine region of the Sinai Peninsula in Egypt

We compared helminth communities in spiny mice (Acomys dimidiatus) from 4 wadis in the arid montane region of the southern Sinai in Egypt, in a 4-week period in late summer. Total helminth species richness was 14 (8 nematodes, 5 cestodes and 1 acanthocephalan) with 94% of mice carrying at least 1 species and an overall mean species richness of 1.85. The most prevalent parasites were Protospirura muricola (47.8 %) and Dentostomella kuntzi (46.3%). One larval cestode, Joyeuxiella rossicum, represents a new host record. The helminth community was dominated by intestinal nematodes (88.7%) of which 58.2% were arthropod-transmitted heteroxenic species. At the component community level, 70% of the worms were recovered from mice in just two wadis (Gharaba and Tlah) and 48.6 % of intestinal nematodes were from Wadi Gharaba. Although only 7 species of helminths were recorded from Wadi Gharaba, this site gave the highest Berger-Parker dominance index because of P. muricola. P. muricola was also dominant in Wadi El Arbaein whilst Syphacia minuta was the dominant species in Wadis Gebal and Tlah. At the infracommunity level, mean species richness and Brillouins index of diversity were highest in Wadi Tlah and lowest in Wadi Gebal, and the former was age dependent. Whilst mice from different wadis differed in the nematodes that were most common, those from Wadi Gharaba carried the highest mean number of worms/mouse. The abundance of P. muricola in particular varied markedly between sites: Wadi Gharaba was distinct as the site showing the highest mean worm burden whereas mice from Wadi Gebal were uninfected. None of the directly transmitted oxyuroid nematodes showed significant variation in abundance between wadis, or host sex or age classes. Overall, the single extrinsic factor in the study, site of capture, was more important than the intrinsic factors in explaining variation in helminth communities in the region. We conclude that in the high mountains of southern Sinai, each wadi is distinct in terms of its rodent parasites, and hence we expect spatially different coevolutionary pressures on their hosts, with resultant variation in life-histories.

Intestinal helminths of spiny mice (Acomys cahirinus dimidiatus) from St Katherine's Protectorate in the Sinai, Egypt

Spiny mice, Acomys cahirinus dimidiatus, inhabiting the wadis close to St Katherine in the mountains of the Sinai peninsula, were trapped and their helminth parasites were studied. Sixty one mice provided faeces for analysis and 27 were killed and autopsied. Six species of helminths were recorded (the spirurid nematodes, Protospirura muricola (74.1%) and Mastophorus muris (11.1%), the oxyuroid nematodes, Dentostomella kuntzi (59.3%), Aspiculuris africana (3.7%), and Syphacia minuta (3.7%) and the hymenolepidid cestode Rodentolepis negevi (18.5%)). The spirurids were the dominant species present, accounting for up to 0.87% of total host body weight. Analysis of worm weights and lengths suggested that transmission had been taking place in the months preceding our study. No sex difference in the prevalence or abundance of spirurids was detected. Significant differences were identified in the abundance of total nematode burdens and the mean helminth species richness between the three wadis which provided multiple captures of mice. There was also a marked effect of host age on both parameters. A highly significant positive correlation between spirurid egg counts and total worm biomass indicated that non-invasive techniques based on egg counts could be used to quantify worm burdens and when this technique was applied to a larger sample size (n = 61), a significant difference between sites but no host sex or age effects were detected for spirurid faecal egg counts. The data suggest that there are differences between helminth component communities infecting spiny mice in different neighbouring wadis, a hypothesis which will be explored further through our continuing studies in the Sinai.

Spatial variation in selection in a plant-pollinator system in the wadis of Sinai, Egypt

We studied an insect-plant pollination system in adjacent steep-sided wadis and a connecting plain in the mountains of southern Sinai (Egypt): this environment creates a strongly divided habitat, which may promote the local differentiation of sub-populations. We tested for spatial differences in phenotypic reproductive characters of the only plant flowering abundantly in early spring, Alkanna orientalis (Boraginaceae), and its major pollinator at that time of year, Anthophora pauperata (Apoidea, Anthophoridae). There were significant morphological differences between sub-populations of Alkanna, mainly between plants from the narrower wadis and those on the interconnecting plain. Flowers on the plain were larger, with wider corollas and more nectar standing crop; these plants retained more flowers on the inflorescence, but received many fewer visits to flowers. There was a significant selection gradient between flower size and maternal fitness (seed set) in the plain, but not elsewhere. Natural selection may have increased resources devoted to attracting insect visitors in response to fewer pollinating visits in the plain. Consistent with this explanation, by experimentally manipulating flower number per plant, we showed that within a wadi having more flowers on a plant secured more visits.

Thyme and isolation for the Sinai baton blue butterfly (Pseudophilotes sinaicus)

The distribution of the narrowly endemic butterfly Pseudophilotes sinaicus (Lycaenidae) was studied. Potential habitat within its range was first located and then the quality of that habitat assessed. Degree of shelter, diversity of plant species, and resource area of an individual food plant (Thymus decussatus) all affected habitat quality and together were used to develop an index of habitat suitability applicable to each site. The butterflys distribution was then studied within the identified network of suitable habitat patches: isolated patches with a small resource area were least likely to contain butterflies. Population size in a patch (as opposed merely to patch occupancy) was affected by resource area and the quality of habitat within that patch. Metapopulation processes and variation in habitat quality therefore appear to combine to describe the distribution of patches occupied by P. sinaicus and their population sizes. This finding provides insights into some of the processes operating on an endemic species throughout its geographical range and has important implications for the conservation of this rare butterfly.

Effect of characteristics of butterfly species on the accuracy of distribution models in an arid environment.

Species distribution models show great promise as tools for conservation ecology. However, their accuracy has been shown to vary widely among taxa. There is some evidence that this variation is partly owing to ecological differences among species, which make them more or less easy to model. Here we test the effect of five characteristics of Egyptian butterfly species on the accuracy of distribution models, the first such comparison for butterflies in an arid environment. Unlike most previous studies, we perform independent contrasts to control for species relatedness. We show that range size, both globally and locally, has a negative effect on model accuracy. The results shed light on causes of variation in distribution model accuracy among species, and hence have relevance to practitioners using species distribution models in conservation decision making.

Local variation in helminth burdens of Egyptian spiny mice (Acomys cahirinus dimidiatus) from ecologically similar sites: relationships with hormone concentrations and social behaviour.

Populations of Egyptian spiny mice (Acomys cahirinus dimidiatus) in a fragmented montane wadi system in the Sinai showed significant differences in the abundance of gut helminths. Differences in parasite load between populations were positively associated with measures of androgen activity but showed no significant relationship with glucocorticoid activity. Social discrimination tests with adult males from different wadis showed that those from sites with greater helminth abundance were less likely to investigate odours from other males and were less aggressive when subsequently interacting with the odour donors. Subjects showed markedly more investigation towards the odours of males from distant wadis compared with those from their own or immediately neighbouring wadi, but were less aggressive when confronted with odour donors from distant wadis. Despite this, there was a positive relationship between the amount of investigation towards distant male odour and subsequent aggression towards the male. While aggressiveness was positively associated with measures of androgen and glucocorticoid activity, no significant relationship emerged with individual helminth infection. Thus aggressiveness appeared to relate to overall local population levels of infection rather than individual challenge.

Mechanism of action of honey bee (Apis mellifera L.) venom on different types of muscles

1 The effect of crude honeybee (Apis mellifera)venom on the skeletal, smooth as well as cardiac muscles were studied in this investigation. 2 Perfusion of gastrocnemius-sciatic nerve preparation of frogs with 1 mg/ml venom solution has weakened the mechanical contraction of the muscle without recovery. Blocking of nicotinic receptors with 3 mg/ml flaxedil before bee venom application sustained normal contraction of gastrocnemius muscle. 3 The electrical activity of duodenum rabbits was recorded before and after the application of 1 mg/ml venom solution. The venom has depressed the amplitude of the muscle contraction after 15 min pretreatment with atropine nearly abolished the depressor effect of the venom on smooth muscle. 4 In concentrations from 0.5-2 mg/ml, bee venom caused decrease of heart rate of isolated perfused toad heart. This bradycardia was accompanied by elongation in the P-R interval. A gradual and progressive increase in the R-wave amplitude reflected a positive inotropism of the venom. Application of 5 mg/ml verapamil, a calcium channels blocking agent, abolished the noticed effect of the venom. 5 Marked electrocardiographic changes were produced within minutes of the venom application on the isolated perfused hearts, like marked injury current (elevation or depression of the S-T segment), atrioventricular conduction disturbances and sinus arrhythmias. Atropine and nicotine could decrease the toxic effect of the venom on the myocardium. 6 Results of the present work lead to the suggestion that bee venom is mediated through the peripheral cholinergic neurotransmitter system. General neurotoxicity of an inhibitory nature involving the autonomic as well as neuromuscular system are established as a result of the venom, meanwhile a direct effect on the myocardium membrane stabilization has been suggested.

Combating Desertification through Fish Farming

For many years the relationship between fish farming and agriculture has been built on recycling the discharged water from the cultivated fields into the aquaculture systems. This discharged water was sometimes full of pesticides and chemicals that were hazardous to both fish and humans. But the proposed inte- grated aquaculture and agriculture system is to work in the opposite direction: the drainage water of the aquaculture is recycled for agriculture. In this case, no pesti- cides or hazards are transferred to the fish and, at the same time, plants are irrigated with naturally fertilized water, which has very limited chances of negative impact on the environment or human health. The study revealed no significant difference (P > 0.05) between tilapia fish (Oreochromis niloticus) reared on groundwater and fish grown in the natural open waters, whether in growth rates, total protein or total phosphorus content. The organic matter, total Nitrogen and NH 3 were significantly increased in the drainage water as compared with the supplied water. Irrigating the soil with the drainage water of fish ponds significantly enhanced soil quality, indicated by an increase in organic matter and total nitrogen, and reduced soil salinity. It was concluded that combating desertification can be made effective through integrative fish farming in arid and semi-arid areas with the presence of brackish groundwater. Moreover, not only will it protect lands from degradation and improve their quality, but it will also utilize neglected natural resources in creating a productive community.

Taxonomy and chromosomal analysis of Egyptian Synchortus imbricatus (Klug) (Coleoptera: Noteridae)

Synchortus imbricatus (Klug) is recorded for the first time in Egypt. Egyptian specimens are much smaller than the type series from Mozambique, but Sudanese material described by Omer‐Cooper shows features linking the two extremes. A lectotype is designated for S. imbricatus (Klug). Regimbarts types of S. simplex var. echinatus have been studied, as well as males from the same locality. They are shown to be S. imbricatus and a lectotype is designated. Sharps types of S. sparsus and S. aciculatus have been studied and found to be conspecific with S. simplex Sharp, as suggested by Omer‐Cooper (1972). The chromosomes of Egyptian S. imbricatus are shown to comprise 12 pairs of autosomes plus sex chromosomes which are X1X2Y in the male and X1X1X2X2 in the female, as in Noterus (Bilton, 1992). Unlike Noterus in S. imbricatus the Y‐chromosome is the largest in the nucleus and is largely heterochromatic.