University of Khartoum

Field and Laboratory Evaluation of Botanical and Chemical Preservatives against the Termites Macrotermes Bellicosus (Smeathman, 1781)

Field and Laboratory Evaluation of Botanical and Chemical Preservatives against the Termites Macrotermes Bellicosus (Smeathman, 1781)

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Title: Field and Laboratory Evaluation of Botanical and Chemical Preservatives against the Termites Macrotermes Bellicosus (Smeathman, 1781)
Author: Mohammed, Hussein Abdallah Hajmosa
Abstract: Termite research in the Sudan is meager and fragmentary. This stimulated the author of the present work to study some aspects of the biology of the termite Macrotermesbellicosus (Smeathman 1781), Field graveyard experiments were done in Sero and JebailElobied Forests of Sennar State, Sudan. Termites used in laboratory experiments were collected from the forests mentioned above using homemade corrugated cardboard traps.The spatial distribution, and relative abundance, colony status, and mound soil density relative to top soil density of the area were studied in a 2.5-hectare strip (50 × 500 m) in each forest. Mounds of M. bellicosus, in both forests, were found to show cluster distribution and linear arrangement along a north/east direction. Clusters of mounds were more dispersed and less dense in the cellulose-poorer JebailElobied Forest (3.6 mound ha-1) than in Sero Forest (7.6 mound ha-1). There were no significant statistical differences in the dimensions (radius and height) as well as the size between mounds of the two forests. Correlation between radius and height of a mound was found to be positive and ranged between moderate to high. In JebailElobiedForest, slightly less than 80% of the colonies were healthy, 10% were Moribund/weakening and 10% were eliminated. In the cellulose-richer Sero Forest, about 52% of the colonies were healthy, 16% were Moribund/weakening and 32% were eliminated. The density of the topsoil of JebailElobied Forest was found to be significantly higher than that of all other types of soils measured. The turnover of soil, as measured by the weight of termite mound soil (in metric ton/hectare) was about 4.5 ton/hectare in Sero Forest compared to JebailElobied Forest, 1.0 ton/hectare.Statistical analyses of the data obtained, showed that in all cases, the extracts significantly protected the wood baits. In untreated baits, the damage due to termite attacks ranged from 1% to 71% with a mean of 21%±6.1 % confidence limits, while in treated baits the range extended from 7% to 15% with a mean of 8% ± 0.8 % confidence limits. Preservative retention, regardless of types of wood, preservative and concentration applied, varied between a minimum of 0.023 kg/m3 and a maximum of 1.071 kg/m3 and with an average of 0.342 kg/m3. However, in all cases, the amount of preservative retention increased significantly with the increase of preservative concentration applied with a minimum average of 0.046 kg/m3 at 2% and a maximum average of 0.736 kg/m3 at 16%. In the acrylic cylinder test the untreated wood baits (the control) were severely attacked by the termites compared to the treated ones. Although there were tendencies for weight loss and survival rate to be the function of preservative type, their concentrations and type of wood species, the differences were not statistically significant. The survival rate of termites in the acrylic test was generally low. In the control tests with blank wooden baits, the survival rate ranged between 80 and 85% at the end of the first week and between 33 and 47% at the second week. The survival rates in acrylic cylinders with treated baits were significantly lower than the control ones. There were no appreciable statistical differences between the values of the termite survival rates in all acrylic cylinders with treated baits. The survival rate ranged between 70-75% at the end of the first week and between 22-29% at the end of the second week. However, all test termites died at the end of the third week.In a set of two-choice orientation bioassays, confirmed that the test extracts had notable deterrent effects on termite workers.Groups of worker termites were tested in the two-choice chamber. Generally, the strong hygropositive reactions of termites override their reactions to other substances. However, aqueous solutions of boric acid and Neem seed kernel oil showed marked deterrent effects.Acute 24-hour toxicity of the preservatives used were tested in a simple device made up of glass bottles. The results showed that the log doses formed a linear relationship with probit mortality with a positive regression coefficient (r) approaching perfection (+0.9902).Time mortality bottle bioassay showed that from five doses tested, 0.6 µg/cm2 boric acid gave 50% in about 45 minutes.
URI: http://khartoumspace.uofk.edu/123456789/25846


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