Products derived from the leaves of Ocimum kilimandscharicum (Labiatae) as post-harvest grain protectants against the infestation of three major stored product insect pests

Abstract

The bioactivity of materials from the leaves of Ocimum kilimandscharicum was tested against Sitophilus zeamais Mots chulsky (Coleoptera: Curculionidae), Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) and Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) in maize and sorghum grains in the laboratory. Exposure of adults of the three insect species to dried ground leaves and essential oil extract of O. kilimandscharicum induced 100% mortality after 48 h. Fresh and dried whole leaves were not toxic to Sitophilus zeamais or R. dominica. Grains treated with dried ground leaves and essential oil extract caused significant reductions in the number of progeny and survival rate of all three pest species tested. There was no adult survival or progeny production in grains treated separately with each of the two materials at doses of 25.0 g (dried ground leaves) and 0.3 g (essential oil) per 250 g of grain, respectively. Unlike R. dominica and Sitotroga cerealella, grains treated with fresh leaves enhanced the feeding activity of Sitophilus zeamais. Ground leaves and the essential oil, however, protected the grains against feeding by all three species, resulting in lower weight loss and number of damaged seeds compared with untreated grains. All the plant materials were repellent to S. zeamais with the essential oil extract applied at 0.3 g/250 g of grain evoking the highest repellent action. There was, however, considerable variation in the repellency of the materials against R. dominica and Sitotroga cerealella. The results are discussed in terms of the efficacy of O. kilimandscharicum for protection against loss due to insects in traditional grain storage in developing countries.

Repellency of live potted plants against Anopheles gambiae from human baits in semi-field experimental huts.

“…The latter four species were included in the test as candidate repellent plants based on empirical information from our own unpublished work and from the literature. [13][14][15] The other five species were selected for experimentation based on ethnobotanical information obtained locally. 12 Furthermore, the impact of the combined use of two repellent plants (O. americanum with either L. camara or L. uckambensis) in reducing house entry and human feeding by mosquitoes was also evaluated.…”

Evaluation of Contact Toxicity and Fumigant Effect of Some Medicinal Plant and Pirimiphos Methyl Powders against Cowpea Bruchid, Callosobruchus maculatus (Fab.) [Coleoptera: Chrysomelidae] in Stored Cowpea Seeds

“…This is because all the life stages, particularly the eggs are very sensitive to cold (Koehler, 2003). The disinfested cowpea seeds were then placed inside a Gallenkamp oven (Model 250) at 40 0 C for 4 hours (Jambere et al, 1995) and later air dried in the Laboratory to prevent mouldiness (Adedire et al, 2011) before they were stored in plastic containers with tight lids disinfested by swabbing with 90% alcohol.…”

Evaluation of Orange Peel Citrus Sinensis (L) As a Source of Repellent, Toxicant and Protectant against Zabrotes Subfasciatus (Coleoptera: Bruchidae)

“…Finally the air reaches the two arms of the "Y" tube glass which is attached to the stem where the insects are released. After this set up following the method of Jembere et al (1995), twenty five adults of each Z. subfasiatus of mixed sex and age were released into the "Y" olfactometer glass. After 30minutes, the numbers of insects which moved into the untreated (Nc) and treated bottle (Nt) were counted.…”