Host Suitability of Crops under Yam Intercrop to Root-knot Nematode (Meloidogyne incognita Race 2) in South-Western Nigeria

Twelve crops commonly grown in association with yam in South-Western Nigeria were evaluated for resistance to root-knot nematode Meloidogyne incognita (Kofoid and White 1919) Chitwood 1949, race 2 infection using the quantitative modification by Sasser et al. (1984) of host suitability designations of Canto-Saenz (1983) for plants infected with root-knot nematode in 1998 and 1999 planting seasons. Observations, based on gall indices and recovery of the juvenile larvae from the roots and soil indicated that Abelmoschus esculentus, Corchorus olitoris cv Angbadu and Sphenostylis stenocarpa cv Nsukka Brown were highly susceptible, while Arachis hypogaea cv UGA 4, Cajanus cajan cv Cita-2, Cucumis melo cv Bara To139, Manihot esculenta cv TMS 30572, Sorghum bicolor and Zea mays cv DMR-LSR-Y were hyper-susceptible to Meloidogyne incognita race 2 with reproductive factor and gall index of ≤1 and ≥2 respectively. Crotalaria juncea, Mucuna cochinchinensis and Stylosanthes gracilis were resistant to Meloidogyne incognita race 2 with reproductive factor and gall index of ≤1, ≤2 and ≥2 respectively. These intercrops if planted on yam mounds will play a prominent role in altering the populations of root-knot nematode Meloidogyne incognita race 2

Karyomorphotypic variation in Eriospermum abyssinicum Baker

The karyomorphology of the cotton seed lily, Eriospermum abyssinicum Baker (family Eriospermaceae) was investigated through mitotic and meiotic studies. The chromosome complement was karyotypically analysed based on chromosome arm ratio and centromeric indices. The somatic chromosome complement of 2n = 24 recorded at metaphase I and the 12 bivalents at prophase I of meiosis suggested x = 6 basic chromosome number and paleopolyploidization process in the evolution of this species. There was no evidence of B chromosome or nucleolar-organizer in the complements. Variation in position of centromere ranged from the median to sub-median and sub-terminal. We found slight variation between some homologues in terms of lengths which suggest hybrid origin (allopolyploidy) of the genome. The microspore mother cell had normal meiosis with subsequent formation of 4 daughter nuclei and normal spores suggesting that the changes in chromosome behaviour occurred at very low frequency and these changes were transient with no evidence of phenotypic and genomic instability (aneuploidy) consequences. It was therefore inferred that the population of E. abyssinicum studied might have evolved through changes in chromosome structure or through natural hybridisation between closely related populations.Key words: Eriospermum abyssinicum, lily, chromosome, karyotype

Pathogenicity of Beauveria bassiana (Balsamo-Crivelli) and Metarhizium anisopliae (Metschnikof) isolates against life stages of Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae)

Background Entomopathogenic fungi are primary pathogens that naturally afect insect pests by suppressing their populations and considered as an ecofriendly agents. The present study aimed to evaluate in vitro activity of diferent isolates of Beauveria bassiana and Metarhizium anisopliae against the development of larval stages of the Cucurbit fruit fy, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae). Results Larval mortality was signifcantly high with B. bassiana isolate Bb337 (5.82–21.70%) and with the lowest in M. anisopliae isolate MaD (1.49–6.33%). Pupal mortality rate was comparatively higher with more than 50%. The cadavers of all host instars produced conidia (sporulation). Sporulated dead larvae were signifcantly higher in Bb337 (61.10%) than at the least in MaD (18.60%) at 105 conidia/ml. At 108 conidia/ml, MaD induced the highest pupal cadavers with mycosis (32.42%). Regardless of applied fungal species, host instars mortality signifcantly increased with increasing concentration of B. bassiana isolates, suggesting a concentration-dependent response of Z. cucurbitae. Conclusion The tested isolates demonstrated their pathogenicity through vertical transmission of mycosis from one instar to another, regardless of the concentrations used

Characterisation of methylphenidate-induced excitation in midbrain dopamine neurons, an electrophysiological study in the rat brain

Methylphenidate (MPH) is a drug routinely used for patients with attention deficit and hyperactivity disorder (ADHD). Concerns arise about psychostimulant use, with dramatic increases in prescriptions. Besides, antipsychotic drugs are often administered in combination with MPH. In this study, we examine the consequences of MPH exposure in combination with dopamine D receptor antagonism (eticlopride) on midbrain dopaminergic neurons in anaesthetised rodents, using in vivo extracellular single-cell electrophysiology. As expected, we show that methylphenidate (2 mg/kg, i.v.) decreases the firing and bursting activities of ventral tegmental area (VTA) dopamine neurons, an effect that is reversed with eticlopride (0.2 mg/kg, i.v.). However, using such a paradigm, we observed higher firing and bursting activities than under baseline conditions. Furthermore, we demonstrate that such an effect is dependent on dual alpha-1 and dopamine D receptors, as well as glutamatergic transmission, through glutamate N-Methyl-D-aspartate (NMDA) receptor activation. Chronic MPH treatment during adolescence greatly dampens MPH-induced excitatory effects measured at adulthood. To conclude, we demonstrated here that a combination of methylphenidate and a dopamine D receptor antagonist produced long-lasting consequences on midbrain dopamine neurons, via glutamatergic-dependent mechanisms

Phenotypic Variability and Diversity Analysis of Bean Traits of Some Cocoa Hybrids in Nigeria

Abstract: It is essential to understand the economic potential and superiority among cocoa hybrids. Therefore, the present study aims at detecting variability among cocoa hybrids for bean index in Nigeria. Dried bean of fourteen genotypes of cocoa were evaluated for their bean values. Analysis of variance (ANOVA) was used to understand the variability among the fourteen genotypes and Principal Component Analysis (PCA) was employed to identify distinguishing traits and the grouping of the genotypes based on similarities. The fourteen cocoa genotypes were significantly (p#0.05) different from each other with respect to weight of one bean, bean length, width, thickness, 100 bean weight, bean length to width, length to thickness and width to thickness ratio. All the studied morphometric characters exhibited high (>70%) broad sense heritability. G8, the hybrid between T53/5 and N38 was the most superior genotype for bean weight and some other bean characteristics. The mass of seventy-four dried cocoa bean of G8 approximated 100 g. The first three Principal Component axes explained 91% of the total variation and the PCA grouped the fourteen genotypes into four distinct clusters. Genotypes could be selected for specific traits and improvement of traits seemed to be genetically reliable

Chronic methylphenidate treatment during adolescence has long-term effects on monoaminergic function

BACKGROUND Psychostimulants like methylphenidate or D-amphetamine are often prescribed for attention deficit and hyperactivity disorders in children. Whether such drugs can be administered into a developing brain without consequences in adulthood is still an open question. METHODS Here, using in vivo extracellular electrophysiology in anesthetised preparations, combined with behavioural assays, we have examined the long-term consequences in adulthood of a chronic methylphenidate oral administration (5 mg/kg/day, 15 days) in early adolescent (post-natal day 28) and late adolescent (post-natal day 42) rats, by evaluating body weight change, sucrose preference (indicator of anhedonia), locomotor sensitivity to D-amphetamine and electrical activities of ventral tegmental area dopamine and dorsal raphe nucleus serotonin neurons. RESULTS Chronic methylphenidate treatment during early or late adolescence did not induce weight deficiencies and anhedonia-like behaviours at adulthood. However, it increased bursting activities of dorsal raphe nucleus serotonin neurons. Furthermore, chronic methylphenidate treatment during early but not during late adolescence enhanced D-amphetamine-induced rearing activity, as well as ventral tegmental area dopamine cell excitability (firing, burst and population activity), associated with a partial desensitisation of dopamine D auto-receptors. CONCLUSIONS We have demonstrated here that early, but not late, adolescent exposure to oral methylphenidate may induce long-lasting effects on monoamine neurotransmission. The possible clinical implication of these data will be discussed

Pathogenicity of Beauveria bassiana (Balsamo-Crivelli) and Metarhizium anisopliae (Metschnikoff) isolates against life stages of Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae)

Abstract Background Entomopathogenic fungi are primary pathogens that naturally affect insect pests by suppressing their populations and considered as an ecofriendly agents. The present study aimed to evaluate in vitro activity of different isolates of Beauveria bassiana and Metarhizium anisopliae against the development of larval stages of the Cucurbit fruit fly, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae). Results Larval mortality was significantly high with B. bassiana isolate Bb337 (5.82–21.70%) and with the lowest in M. anisopliae isolate MaD (1.49–6.33%). Pupal mortality rate was comparatively higher with more than 50%. The cadavers of all host instars produced conidia (sporulation). Sporulated dead larvae were significantly higher in Bb337 (61.10%) than at the least in MaD (18.60%) at 105 conidia/ml. At 108 conidia/ml, MaD induced the highest pupal cadavers with mycosis (32.42%). Regardless of applied fungal species, host instars mortality significantly increased with increasing concentration of B. bassiana isolates, suggesting a concentration-dependent response of Z. cucurbitae. Conclusion The tested isolates demonstrated their pathogenicity through vertical transmission of mycosis from one instar to another, regardless of the concentrations used