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Background: The insecticidal activities of essential oils from seeds of five botanicals Tetrapleura tetraptera, Annona muricata, and Aframomum melegueta and leaves of Eucalyptus globulus and Ficus exasperata were evaluated as biopesticides against the storage pest of cowpea Callosobruchus maculatus (Fabricius). The oils were applied at the concentration of 1 ml/kg, 3 ml/kg, and 5 ml/kg of cowpea seeds mixed evenly. The experiment was laid out in a completely randomized design. The parameters assessed include the percentage of mortality, oviposition, adult emergence, seeds damaged, weight loss, and germinability capacity of the protected seeds. Results: The results from the study showed that the effectiveness of the essential oils was dependent on application rates and time of exposure. In the treated cowpea seeds, A. melegueta essential oil was the most effective with 50% lethal concentration (LC50) value of 2.42 ml/kg and 95% lethal concentration (LC95) value of 4.86 ml/kg when compared to the other treatments as indicated by the application rate which caused 50% and 95% mortality of cowpea beetles. A. melegueta essential oil at the concentration of 5 ml/kg achieved 100% mortality of C. maculatus at 48 h of application. Cowpea seeds treated with 5 ml/kg of E. globulus essential oil significantly reduced (P < 0.05) oviposition compared to the other treatments. Cowpea seeds treated with 5 ml/kg of A. muricata essential oil reduced adult emergence (3.67) and weight loss (0.59). The cowpea seeds treated with essential oils at different concentrations had no significant (P > 0.05) adverse effect on seed germination after 120 days of storage. Conclusion: Based on the findings of this study, the essential oils could be explored as an alternative bio-pesticide to synthetic insecticide in the protection of stored cowpea against C. maculatus.

The toxicity effects of the combination of Nicotiana tabacum leaf powder and pirimiphos-methyl dust as a treatment is compared with sole treatment of the powder and dust in this study. All laboratory experiments were conducted under prevailing conditions of 28±3 0 C and 70±5% relative humidity. Contact toxicity of Nicotiana tabacum powder was tested on Sitophilus zeamais at 0.4g and 0.01g of pirimiphos-methyl powder per 20g of maize seeds singly. The toxicity of combined powder of N. tabacum at 0.2g with 0.0013g, 0.0025g and 0.005g of pirimiphos-methyl dust per 20g of maize seeds was also tested. These treatments significantly (p>0.05) reduced the weight loss and adult emergence of S. zeamais. The powder and dust also caused high mortality to S. zeamais when applied.The efficacy of the Nicotiana tabacum was better when applied singly at 0.4g than when combined with dust of pirimiphos-methyl at reduced rates. Irrespective of the treatment used in the study, the response of Sitophilus zeamais was found to be dependent on the concentration. Adult mortality increases with concentration, while adult emergence reduces. The results of this study revealed the effects of combined botanicals with reduced rates of conventional insecticides as an alternative in the management of stored product insect pests.

Fall armyworm (FAW; Spodoptera frugiperda), an exotic moth which recently invaded Africa, is a highly destructive pest of cereals especially maize a highly valued staple crop in Nigeria. The use of natural enemies such as predators or parasitoids for FAW control is more economically viable and environmentally safer than currently recommended synthetic insecticides. Natural enemies to combat the pest have not yet been reported in Nigeria. An exploration for the pests’ natural enemies was undertaken by collecting FAW eggs and larvae from maize fields. These were reared in the laboratory for emergence, identification and efficacy as natural enemies. This yielded Euplectrus laphygmae (Hymenoptera: Eulophidae); Telenomus remus (Hymenoptera: Platygastridae) and Trombidium sp. (Acari.: Trombidiidae). Cotesia or Apanteles spp. were inferred to occur since Stictopisthus sp. (Hym.: Ichneumonidae), a secondary parasitoid, that attacks cocoons of Microgasterinae (e.g. Cotesia, Apanteles etc.) also emerged. Species of yet-to-be identified predators were also observed in various niches of maize plants. A positive relationship was found between FAW instar and the number of E. laphygmae eggs/instar ranging, on average, from 1.5 on second instar to 5.5 on fourth instars hosts. Parasitism rate of T. remus on FAW eggs was 100%. Parasitic mite infestation resulted in increasing paleness, reduced feeding, growth and movement as well as death of FAW 1st instars. Thus, the occurrence of FAW natural enemies in Nigeria calls for advocacy campaign to incorporate their use into integrated pest management strategies that attract and allow natural enemies to thrive for FAW management.

Dennettia tripetala powder and reduced rates of pirimiphos-methyl dust were tested on cowpea against C. maculatus for their effective management. The study was conducted under ambient conditions of 25 0 C -28 0 C and 65% -75% relative humidity in the laboratory for a period of 3 months. Powder of D. tripetala and dust of pirimiphos-methyl were tested sole at 0.4g and 0.1g per 20g of cowpea seeds respectively while various combinations at 0.2g DT + 0.05g PM, 0.2g DT+ 0.025g PM, and 0.2g DT + 0.0013g PM were also tested on 20g of cowpea seed. D. tripetala powder was more effective at 0.4g when applied singly. Adult mortality of more than 80% occurred in less than 3 days. It also caused a significant reduction in oviposition, adult emergence and weight loss after emergence. Effect of sole application of pirimiphos-methyl dust at 0.1g per 20g of cowpea seed was less when compared with 0.4g of D. tripetala. The combined treatments of D. tripetala and pirimiphosmethyl slightly reduce adult emergence and weight loss. This study revealed better performance of D. tripetala powder when applied singly over reduced rates or even when combined with pirimiphos-methyl against cowpea seed beetle.

Oil extract of three plant insecticides, Acalypha godseffiana, Annona muricata and Petiveria alliaceae were evaluated as protectant against field pest of three major Solanum species cultivated in Nigeria. The experimental design was laid out in a completely randomized block design with each treatment replicated three times. The results indicated low level in severity of shoot damage among Solanum macrocarpon bio-pesticide treated plants and their interactions. Higher fruit damage severity (13.93%) was reflected in untreated S. macrocarpon interactions. Findings from the study reflected a coefficient of determination  (R2) = 0.18 between plant oil treatments and fruit yield of eggplant species, which implies that 18% of the variance in fruit yield of eggplant species can be attributed to the plant oil treatments. Further screening of the active components of the botanicals for insecticidal potency is hereby recommended.

The efficacy of powder mixes of two different insecticidal plants against Callosobruchus maculatus Fabricius was determined at the Entomology Research Laboratory, Department of Crop, Soil and Pest Management of the Federal University of Technology, Akure, Ondo State, Nigeria, under ambient laboratory conditions of 26 ± 4° C and 65 ± 10% RH. The powder combinations were made from Azadirachta indica leaf Thaumatococcous daniellii rhizome Eugenia aromatica dry flower buds, seeds of Piper guineense and rhizome of Zingiber officinale in a 1:1 ratio. The binary combinations were assessed at the dosages of 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 and 2.0 g per 20 g of cowpea seeds in separate 250 ml plastic containers with lids, against five pairs of newly emerged C. maculatus adults. Insect mortality was recorded 24, 48 and 72 hours post treatment and the number of F1 adult emergence was recorded after up to 35 days post treatment. The combination of E. aromatica and T. daniellii, and E. aromatica and Z. officinale produced 60% and 53% mortality respectively, of adults of C. maculatus at the lowest tested dosage (0.2 g/20 g of grain), and 100% and 83% mortality respectively, at the highest tested dosage (2.0 g/20 g of grain). Oviposition and progeny production of C. maculatus were also significantly lower in treatments involving the use of these two combinations; significantly fewer seeds bore beetle eggs and adult exit holes. The combination of E. aromatica and T. daniellii, and E. aromatica and Z. officinale may be included in pest management strategies for mitigating C. maculatus damage to stored cowpea.

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