Evaluation of SpinTor™ Dust in the Protection of dried Tilapia niloticus against Dermestes maculatus (De geer) (Coleoptera: Dermestidae)

Introduction: Dermestes maculatus is a major pest of stored fish in Nigeria causing as high as 50% weight loss. Fishermen spray insecticides injudiciously which include Gamallin 20 which constitute danger to human health. SpinTor dust (Spinosad) is a commercially reduced-risk pesticide that is naturally derived from the fermentation from a soil bacterium, Saccharopolyspora spinosa. Objectives: No reference data on its efficacy in suppressing major insect pest of stored fish have been published. This paper therefore evaluated the efficacy and residual effect of SpinTor dust against Dermestes maculatus on dried Tilapia fish, Tilapia nilotica. Methods: Disinfested Tilapia was treated with 0.125, 0.25, and 0.5 percent Spintor dust. D. maculatus was introduced into containers holding 50g of untreated and treated fish.  Residual effect of Spintor was evaluated at 30 and 60 days after treatment (DAT). Results: SpinTor dust was more toxic on adults D. maculatus with LD50 of 2.338 than on the larvae with LD50 of 2.693. Adult mortality was highest in the dried Tilapia niloticus treated 0.5% SpinTor dust and least in the control. No larva developed in 0.5% concentration while 629 larvae developed in the control. A significant higher number of F1 adults that emerged from (0.5% concentration) treated adults died when compared with all the other treatments and control. Histopathological test on the liver of mice showed no significant weight gain in mice fed on treated fish and the control after three months. The histopathological test of the liver of the control treated  mice had no alterations in their hepatic lobes. Conclusion: Spintor dust can be used to protect dried fish against D. maculatus Key words Toxicity, Spinosad, Dried fish, Mortality, LD50, Residue, liver and Mice

Evaluation of cowpea genotypes for field resistance to the legume pod borer, M. testulalis in Nigeria

Eighteen cowpea cultivars were screened for resistance to the legume pod borer, Maruca testulalis under field conditions at two locations (Mokwa and Ibadan) in Nigeria under unprotected and two types of insecticide protection levels. Unprotected plots gave zero yield due to their exposure to the entire cowpea pest complex. Plots that received a mixture of Cypermethrin and dimethoate (as Cymbush Super ED®) treatment were better (P < 0.05) than plots treated with monocrotophos (as Nuvacron 40EC) in all the damage parameters studied. Results showed that larval population per se are not adequate in resistance categorization of cowpea cultivars. For percentage pod damage at both locations, TVu 946, MRx2-84F and MRx109-84F were the best three cultivars while IT82D-716 was the worst. Yield reduction caused by M. testulalis at Ibadan ranged from 3.47% in MRx2-84F to 49.75% in IT82D-716; at Mokwa values ranged from 10.65% for MRx54-84M to 52.23% for MRx15-84F. Based on their yield performance, among other resistance parameters, the following eight cultivars were selected as moderately resistant to M. testulalis: MRx2-84F, MRx49-84M, MRx109-84M, MRx50-84M, MRx54-84M, MRx55-84M, MRx8-84F and MRx48-84M. These cultivars have good plant type and are either white or brown seeded which makes them good candidates that could be used in breeding programme

Plant powders protect stored wheat from infestation by lesser grain borer Rhyzopertha dominica (fabricius) (Bostrichidae: Coleoptera)

Rhyzopertha dominica (Bostrichidae: Coleoptera) is one of the most serious devastating insect pests attacking stored wheat grains in Nigeria. The most common strategy adopted in controlling this insect pest is the application of synthetic pesticides which is costly, toxic to non-target organisms and is non eco-friendly. Botanical pesticides are recently used as alternatives to synthetic pesticides due to their non-hazardous effect on the environment and non-target organisms, cost effectiveness and direct impacts on the target organisms. This study was carried out to determine the toxicity of leaf powders obtained from three species of plants: Ageratum conyzoides, Momordica charantia and Tephrosia vogelii in the control of R. dominica infestation on stored wheat grains. Five doses (0.50, 1.00, 2.00, 4.00 and 8.00 g) per 20.00 g were measured from the powdered leaves of the tested plants with ethanol treatment as the control (0.00 g 20.00 g-1). The powdered doses were applied onto wheat grains before the insects were introduced. The experiment was laid down in completely randomized design (CRD) with three replications. The data obtained was analyzed using analysis of variance at 5% probability level with Least Significant Difference used to separate the means. The results showed significant (p ≤ 0.05) differences in the magnitude of toxicity imparted by various doses of the powders on R. dominica. The treatments influence high rate of mortality, reduced number of laid eggs and emerged adults when compared with the control. The toxicity of the powders increased with increase in dosage. It was concluded that 8.00 g 20.00 g-1 of the powders were more toxic to R. dominica, inducing 28.00-77.30% insects’ mortality thereby protecting grain damage to as low as 1.04% at 6th month of storage. T. vogelii leaf powders were recommended for use against R. dominica in stored wheat grains. Key words: botanicals, dose, lesser grain borer, whea

Podwall toughness has no effect on cowpea resistance to the legume pod borer

The possibility of the involvement of pod wall toughness in the resistance of cowpea, Vigna unguiculata (L.) Walp., to the legume pod borer, Maruca testulalis was studied. The toughness of non-intact and intact pod wall increased with age, but the rate varied at different growth stages of the pod as well as between cultivars. There was a positive and significant correlation (r = 0.82**) between pod age and pressure required to penetrate pod wall. No significant differences (P > 0.05) were observed in non-intact pod wall toughness between TVu 946 (resistant) and IT82D-716 (susceptible) at all the growth stages tested. However, significant differences (P < 0.05) were observed between these two cultivars for only 6-day-old intact pods where IT82D-716 recorded a higher value than TVu 946. Correlation between pod damage severity by M. testulalis and toughness of non-intact and intact pod wall of these cultivars at different growth stages were not significant. While pod wall toughness would be a desirable trait, it is concluded from this study that pod walls of the cultivars studied did not play any appreciable role on cowpea resistance to the larvae of M. testulalis

Cowpea plant architecture in relation to infestation and damage by the legume pod borer, Maruca testulalis Geyer (Lepidoptera: Pyralidae) 1. effect of canopy structure and pod position

The effects of cowpea, Vigna unguiculata (L.) Walp. canopy structure and pod position in relation to infestation and damage by the legume pod borer, Maruca testulalis Geyer were investigated. Defoliated cultivars sustained significantly less infestation and damage (P < 0.05) than those undefoliated. Relative humidity measured under the canopy was lower in defoliated cultivars, while soil and ambient temperatures were higher. Percentage pod damage and larval infestation by M. testulalis in flowers were positively correlated with relative humidity, and negatively correlated with temperature. Both correlations were significant (P < 0.01). Cultivars with pods held within the canopy suffered significantly more damage (P < 0.05) than cultivars whose pods were held in the normal position. Canopy structure and pod position acting together or independently, exerted profound effects on cowpea resistance to M. testulalis. Selection and breeding cowpea cultivars with less dense foliage (= open canopies) and long peduncles holding the reproductive structures above the canopy, should increase cowpea resistance to M. testulalis

Ethno - Botanical Survey Of Plant Species Used For Mosquito Control In Nigeria

In Nigeria, there is paucity of information on plants used to repel or kill mosquitoes despite the abundant plant species in the country’s tropical rain forests. Majority of available data are on the traditional use of plants for curative purposes. This study documents some plant species used for insecticidal or repellent purposes against mosquitoes in Nigeria. An ethno-botanical survey was carried out in four geo-political zones in the country using structured questionnaires and focus group discussion. A total of six plant species belonging to five families were reported in Delta state with Conyza Canadensis (Compositae) being the most utilized (50%) and Aspilia africana (Compositae), the least mentioned (5.60%). In Enugu state, a total of nine plant species belonging to eight families were mentioned by respondents with Aframomum melegueta the most utilised (26.09%) while Agava sisalana and Dracaena manii belonging to the families Agavaceae and Dracaenaceae were the least mentioned (1.09% each). A total of six plant species belonging to five families were reported in Kaduna State with Lantana camara belonging to the family Verbenaceae accounting for 58.82% of the utilised plant species for mosquito control while Ipomea asarifolia, Terminalia catappa and Citrullus vulgaris belonging to the families Convolvulaceae, Combretaceae and Cucurbitaceae respectively were the least utilized (5.88% each). Lagos State recorded the highest number of plant species (twenty five) belonging to eighteen families. Spondia mombin belonging to the family Lilaceae was the most mentioned (7.33%) while the least mentioned (0.37% each) were Magnifera indica, Baphia nitida and Pennisetum purpeum belongingto the families Anacardiaceae, Fabaceae and Poaceae respectively. There is a need for further investigation on these plant species as they may constitute potential sources of cidal and repellent compounds against a wide range of insect pests. Keywords: Ethno-botanical survey, insecticidal, repellence, mosquitoes, plant specie