Abundance, diversity and foraging activities of termites under conventional and organic farming systems in the central highlands of Kenya

Abstract

A system comparison (SysCom) program was setup under long-term experiment (LTE) trials to address declining farm productivity due to farm infertilities. The farming systems compared since 2007 were on conventional (Conv) and organic (Org); at High and Low farm input levels; the trials based at Chuka and Thika locations in Kenya. These systems represented a commercial-scale and export-oriented against subsistence productions; receiving maximum vs minimal nutrient and pesticide inputs respectively. A ray of crops were sown firstly over long and into the same plots during short rainy seasons; and so far obtained results showed the potential and advantages of organic over conventional; but with higher presence of termites recorded in trial plots. A further trial over the 2014 to 2015 cropping seasons designed to find reasons discovered farming systems, trial sites, soil profiles and cropping seasons as among key factors significantly (p < 0.05) influencing termite abundance by between 1.5 to 5 folds. The Org-High systems receiving natural organic farm inputs, Chuka site endowed with favorable climatic and ideal clay soil content, the uniformly structured top soil profile, and bean-based cropping registered higher termite population. Nine termite genera identified morphologically and grouped into (i) Macrotermitinae (of genera: Allodontotermes, Ancistrotermes, Macrotermes, Microtermes, Odontotermes and Pseudocanthotermes), (ii) Termitinae (of genera: Amitermes and Cubitermes) and (iii) Nasutitiermitinae (of genera: Trinervitermes) were found in the plots. They belonged and were credited as crop enhancers, foragers, and promoters significantly (p<0.05) improving pH, P(Olsen), K, Ca, and Mg chemical elements under Org-High system. Some physicochemical properties, significantly (p < 0.05) changed after 7 years of continuous farming included soil fraction by 0.273%, moisture content, and permanent wilting point; which were significantly (p < 0.05) changed at Chuka (0.244%) than Thika (0.145%). Similarly soil chemical elements went through significant (p< 0.05) changes by up to two-fold; including macronutrients, micronutrients, and exchangeable cations. Also total and castle termite abundance and their foraging activities assessed through tunneling and number of galleries along soil profiles significantly (p < 0.05) occurred under the system. The high termite numbers were however further explainable to be significantly (p>0.05) and directly affected by soil element the main once being Ca, K, and N and CEC. Further statistical analysis through principal component analysis (PCA) and redundancy analysis (RDA) tools later affirmed these elements to explain some termite genera presence; including Allodontotermes, Ancistrotermes, Trinervitermes, and Amitermes. As a crop pest termite activities variably occurred in importance i.e. firstly recorded on dry maize cultivar (grown under Org-Low) and later on baby corn grown under the High (Org- and Conv-) either way causing minimal economical injuries on to the weakly dry maize cultivar seedling, and on to maturing, showing crop senescence baby corn from where high termite population spared vigorously growing by corn seedling. Part of the reason the baby corn seedlings were spared were the presence of the readily available farm inputs that were more preferred as feeds the seedling being spared. In particular the lodging damage by termites were exclusively reported at Thika site, closely associated with Odontotermes, Macrotermes, and Pseudacanthoterme termite genera; as tunneling damage recorded from both the sites closely associated with Microtermes, Amitermes, and Ancistrotermes. Either way the two damage types caused minimal (i.e. below 5%) maize crop damage losses. In conclusion, the possibilities of mass rearing of termites in large population in agricultural fields can be possible and the possibilities manipulating them in agricultural fields to change soil properties and to enhance sustainable crop productivity under Org-High farming systems in the long run exist as an achievement from the study.