Linking spatial distribution of Rhipicephalus appendiculatus to climatic variables important for the successful biocontrol by Metarhizium anisopliae in Eastern Africa.

Cattle production is constantly threatened by diseases like East Coast fever, also known as theileriosis, caused by the protozoan parasite Theileria parva which is transmitted by ticks such as the brown ear tick, Rhipicephalus appendiculatus. To reduce the extensive use of chemical acaricides, fungal-based microbial control agents such as Metarhizium anisopliae have been tested and show promising results against R. appendiculatus both in field and in semi-field experiments in Africa. However, no known endeavors to link the spatial distribution of R. appendiculatus to climatic variables important for the successful application of M. anisopliae in selected East African countries exists. This work therefore aims to improve the successful application of M. anisopliae against R. appendiculatus by designing a temperature-dependent model for the efficacy of M. anisopliae against three developmental stages (larvae, nymphs, adults) of R. appendiculatus. Afterward a spatial prediction of potential areas where this entomopathogenic fungus might cause a significant epizootic in R. appendiculatus population in three selected countries (Kenya, Tanzania, Uganda) in Eastern Africa were generated. This can help to determine whether the temperature and rainfall at a local or regional scale might give good conditions for application of M. anisopliae and successful microbial control of R. appendiculatus.

Self-organization of plasticity and specialization in a primitively social insect.

Biological systems have the capacity to not only build and robustly maintain complex structures but also to rapidly break up and rebuild such structures. Here, using primitive societies of Polistes wasps, we show that both robust specialization and rapid plasticity are emergent properties of multi-scale dynamics. We combine theory with experiments that, after perturbing the social structure by removing the queen, correlate time-resolved multi-omics with video recordings. We show that the queen-worker dimorphism relies on the balance between the development of a molecular queen phenotype in all insects and colony-scale inhibition of this phenotype via asymmetric interactions. This allows Polistes to be stable against intrinsic perturbations of molecular states while reacting plastically to extrinsic cues affecting the whole society. Long-term stability of the social structure is reinforced by dynamic DNA methylation. Our study provides a general principle of how both specialization and plasticity can be achieved in biological systems. A record of this paper's transparent peer review process is included in the supplemental information.

Evaluation of the Entomopathogenic Fungi Metarhizium anisopliae, Beauveria bassiana and Isaria sp. for the Management of Aphis craccivora (Hemiptera: Aphididdae).

Cowpea, Vigna unguiculata ((L.) Walp; Fabales: Fabaceae), is an important indigenous vegetable and grain legume in the tropics where it represents a major diet component. Cowpea aphid, Aphis craccivora (Koch; Hemiptera: Aphididdae) is a major pest causing up to 100% yield losses. Aiming at establishing alternative approach to synthetic insecticides, we evaluated the pathogenicity of 23 fungal isolates including Metarhizium anisopliae ((Metschn.) Sorokin; Hypocreales: Clavicipitaceae), Beauveria bassiana ((Bals.) Vuill.; Hypocreales: Cordycipitaceae), and Isaria sp. (Hypocreales: Cordycipitaceae) against adult A. craccivora in the laboratory. Adult apterous aphids were sprayed with conidial suspensions titred at 1 × 108 conidia ml-1 for pathogenicity tests while 1 × 104, 1 × 105, 1 × 106, 1 × 107 and 1 × 108 conidia ml-1 were used in dose response bioassays. All the fungal isolates were found pathogenic to A. craccivora, causing mortality of between 34.5 and 90%. The lethal 50% mortality time (LT50) values varied between 3.3 and 6.3 d, with the best isolates being ICIPE 62, ICIPE 41 and ICIPE 644. The lethal concentration mortality (LC50) values were 2.3 × 106, 1.3 × 108 and 1.3 × 109 for ICIPE 62, ICIPE 41, and ICIPE 644, respectively. M. anisopliae isolate ICIPE 62 produced more conidia on aphid cadavers (4.5 × 107) than ICIPE 41 (2.7 × 107) and ICIPE 644 (2.1 × 107) 6 d post-treatment. Relative potency comparison showed that ICIPE 62 was more potent than the other two isolates. In the screenhouse, conidia of ICIPE 62 significantly reduced A. craccivora population compared to control but there was no significant difference between emulsifiable and aqueous formulations. Small-holder leafy vegetable producers could gain more profits using fungal-based biopesticides in Aphid-IPM strategies, leading to reduction of pre-harvest intervals after their application compared to synthetic insecticides.

Laboratory and field evaluation of entomopathogenic fungi for the control of amitraz-resistant and susceptible strains of Rhipicephalus decoloratus.

Rhipicephalus decoloratus causes serious economic losses in cattle industry every year in East Africa. Biological control using entomopathogenic fungi is seen as a promising alternative to chemical acaricides being used for their control. The pathogenicity of Metarhizium anisopliae and of Beauveria bassiana isolates was tested in the laboratory against amitraz-resistant and amitraz-susceptible strains of R. decoloratus. Unfed larvae were sprayed with conidial suspensions of 1×10(9) conidia ml(-1). Fungal isolates were pathogenic to R. decoloratus larvae, causing mortality of between 10.0 and 100% and between 12.1 and 100% of amitraz-susceptible and amitraz-resistant strains, respectively. The LT50 values of selected fungal isolates varied between 2.6-4.2days in amitraz-susceptible strain and between 2.8-3.9days in amitraz-resistant strain. The LC50 values varied between 0.4±0.1 and 200.0±60×10(3) conidia ml(-1) and between 0.1±0.1 and 200.0±31.0×10(3) conidia ml(-1) in amitraz-susceptible and amitraz-resistant strains, respectively. Metarhizium anisopliae isolate ICIPE 7 outperformed the other isolates and was selected for compatibility study with amitraz and field trial. ICIPE 7 was compatible with amitraz. In the field, four treatments including control, ICIPE 7 alone, amitraz alone and ICIPE 7/amitraz were applied on cattle. All the treatments significantly reduced the number of ticks on all the sampling dates: day 7 (F3,8=3.917; P=0.0284), day 14 (F3,8=9.090; P=0.0275), day 21 (F3,8=37.971; P=0.0001) and day 28 (F3,8=8.170; P=0.0016) compared to the control. Results of the present study indicate that ICIPE 7 can be used for the management of amitraz-resistant strain of R. decoloratus.

Hypolipidemic and anti-atherogenic effect of aqueous extract leaves of Ficus glumosa (Moraceae) in rats.

Leaves of Ficus glumosa are used in northern Cameroon and southern Chad for the treatment of cardiovascular diseases, as food and as a stimulant for milk production in both women and animals. Atherosclerosis is a disease in which frequency increases with age. The first lesions appear at the young subject during adolescence. Atherosclerosis lesions appear very precociously and worsen with age. They interest the levels chronologically aortic, coronary then carotid. Age is a risk factor in that it reflects the exposure time of individual to the other risk factors. The frequency of the atherosclerosis increases with age because of the aging of the cells. This study was undertaken to evaluate the hypolipidemic and anti-atherosclerotic properties of aqueous extract of the leaves of F. glumosa in rats with hypercholesterolemia (HC). 60 male rats were fed for 4 weeks with a high-cholesterol diet (1%) and 3 doses (225, 300 and 375 mg/kg) of extract of F. glumosa were used in these experiments. The experiments were conducted under the same conditions with atorvastatin (1 mg/kg), as pharmacological reference substance. The effects of F. glumosa on weight gain, water and food consumption, levels of serum lipids and lipoprotein lipid oxidation and stress markers in the blood and liver were examined. The administration of F. glumosa extract prevented significant (P<0.05) elevation in TC, LDL-c, VLDL-c, hepatic and aortic TG and TC. The atherogenic, triglyceride, and lipid peroxidation (TBARS) indexes were also decreased in the rats treated with the extract. F. glumosa favored the performance of fecal cholesterol. It also significantly inhibited the changes and the formation of aortic atherosclerotic plaques. These results revealed the hypolipidemic and antiatherosclerotic effects of F. glumosa extract and support the traditional use of the extract of this plant in the treatment of hypertension and diabetes.

Diuretic activity of the aqueous extract leaves of Ficus glumosa Del. (Moraceae) in rats.

Experiments were carried out to validate the use of F. glumosa extract as a diuretic in the treatment of hypertension as claimed by traditional healers. The experiments were performed under the same conditions with two synthetic pharmacological diuretics considered as check (Furosemide and Amiloride hydrochlorothiazide). The aqueous extract leaves of F. glumosa accelerated the elimination of overloaded fluid. At the maximum of diuretic response, urinary osmolarity decreased significantly when compared with controls. The single dose treatment of the aqueous extract leaves of F. glumosa has significantly increased urine volume 24 h after administration of the extract. The stability of aldosterone level, the absence of correlation with the plasma levels of sodium, and the increased clearance of free water in the animals receiving the extract show that increased diuresis and natriuresis moderate elevation are tubular in origin. The increase in Na(+), K(+), and Cl(-) induced by the extract caused alkalinization of the urine and showed a strong inhibitory effect of carbonic anhydrase and saluretic. These effects were mainly observed at the dose of 375 mg/kg. These observations confirm the traditional use in the treatment of hypertension and support the importance of the conservation of local knowledge as well as the conservation of Cameroonian biodiversity.

Acute and sub-chronic oral toxicity assessment of the aqueous extract leaves of Ficus glumosa Del. (Moraceae) in rodents.

BACKGROUND: Ficus glumosa Del (Moraceae), a plant used in traditional medicine in Cameroon, Senegal, and East Africa for the treatment of edema, hemorrhoid, cardiovascular diseases especially hypertension. AIM: The present study evaluated the potential toxicity of the aqueous extract of the leaves of F.glumosa in acute and sub-chronic administration in rodents. METHODS: Acute toxicity was evaluated on 3 months old mice of both sexes and weighing 20-30 g. A single dose (2-12 g/kg) of F. glumosa was administered orally to mice. Animal behavior, adverse effects, and mortality were determined for 14 days. In sub-chronic toxicity studied in both sexes of 9 weeks old rats and weighing 100-120 g at the start of the experiment, animals were treated orally with a daily dose of 300, 600 and 1200 mg/kg of the aqueous extract of the leaves of F. glumosa for 6 weeks. The body weight change, food, and water consumption, were determined throughout the experimental period, while the relative organ weights, the hematological and biochemical parameters of blood and urine, as well as the histology of tissues kidney and liver, were recorded at the end of the experiment. RESULTS: For acute treatment, no dose used induced critical behavioral changes or death. In sub-chronic treatment, daily oral administration of F. glumosa at the dose of 300, 600, and 1200 mg/kg resulted in a significant increase in body weight relative to food and water consumption in the last week of treatment. The relative organ weights were not affected by treatment. No hematological changes were observed except the significant increase in platelets. Aspartate aminotransferase, alanine transaminase, alkaline phosphatase, total protein, increased while the total cholesterol, triacylglycerol, conjugated bilirubin, and total bilirubin significantly decreased. Index of renal function showed a decrease of creatinine, urea, uric acid and Na(+), Cl(-) and Ca(2+), and inorganic phosphate. The histology of liver and kidney showed no significant alteration of tissue. CONCLUSION: These observations support the traditional use of F. glumosa in the treatment of hypertension. These results have shown that F. glumosa has a safety margin for therapeutic use.

Antifertility and fetotoxic activities of Acanthus montanus aqueous extract in Wistar rats.

Acanthus montanus T. Anderson (Acanthaceae) possesses several medicinal properties; it is used in Cameroon as a folk medicine to treat pain, inflammation and threatened abortion. The aim of this study was to determine the effect of A. montanus aqueous extract on the estrous cycle pre- and postimplantation in rats and its mechanism of action. The estrous cycles of Wistar rats were monitored before, during and after oral administration of distilled water (control) or aqueous extract (62.5, 125, 250, 500, 1000 mg/kg/day). Furthermore, pregnant rats received the above doses of aqueous extract on days 1-6 (preimplantation) or 6-15 (postimplantation) of gestation and were sacrificed on day 8 or 20 of pregnancy, respectively. Moreover, aqueous extract (500 and 1000 mg/kg/day) was given to ovariectomized rats in the presence or absence of exogenously administered estrogen and/or progesterone and uterine weight and deciduoma count were evaluated. The extract, irrespective of dose, reversibly prolonged the metestrous and occasionally the diestrous stages of the estrous cycle. The extract did not alter the uterine wet weight or deciduoma count, suggesting a lack of estrogenic and progestational effects. At 1000 mg/kg/day, the extract caused appreciable preimplantation losses of 36.8 +/- 6.5% (P < 0.05), while none of the doses caused postimplantation losses. The extract also caused delayed fetal growth.