The ingestion of organic and mineral materials by earthworms is a prominent functional role that has profound consequences for the decomposition and stabilization of soil organic matter. To investigate the litter consumption of the African nightcrawler earthworm Eudrilus eugeniae under different tropical conditions, we used DNA barcoding to identify specimens of E. eugeniae collected from sites across the Adamawa region in Cameroon, and studied the influence of habitat suitability (soil properties), soil moisture, litter type, and population density on litter consumption. A total of four litter consumption experiments were carried out using soils collected from refuse disposal sites, agricultural lands, and savannahs dominated by the Mexican sunflower Tithonia diversifolia. The results revealed that litter consumption significantly increased in the refuse disposal and agricultural soils as opposed to the Mexican sunflower (T. diversifolia) soil, a cow dung enriched substrate, and a sterile soil horizon from the savannah (P < 0.05). The optimum moistures for litter consumption were between 24% and 50%. Litter type did not affect the consumption rate of the earthworms (P > 0.05). We observed a general positive density‐dependent consumption with litter mass loss increasing with increasing density. Our results suggest that E. eugeniae has a strong direct effect on the decomposition of plant materials than expected from previous estimations, and that litter consumption rates are determined by several habitat components and population density.

IntroductionEarthworms are soil invertebrates and taxonomically belong to the phylum Annelida, class Clitellata (Pechenik, 2014). They are mainly found in soils and organic matter accumulations in terrestrial ecosystems, with a few species adapted to aquatic conditions (Tomlin, 2001;Raja and Karmegam, 2009;Siddaraju et al., 2013). Earthworms play a prominent role in regulating soil processes and have been recognized as the most important soil ecosystem engineers (Lavelle, 1988;Santra and Bhowmik, 2001). About 3700 earthworm species have been described to date (Decaëns et al., 2013), mostly from tropical environments. Cameroon has a wide latitudinal range and a very complex topography, which results in a contrasting climate that ranges from equatorial in the southern regions to tropical in the northern regions. It has been divided into 3 large geoclimatic units and 5 vast agroecological zones for the implementation of agricultural planning and policies. The northern part of Cameroon belongs to 2 agroecological zones and 2 geoclimatic units (Suchel, 1988;Ngachie, 1992) and is adequate for assessing regional earthworm populations.Changes in land use pattern directly affect the composition and population structure of earthworm species in different agroclimatic regions (Behera et al., 1999). Processes of land-use changes are increasing in the northern region of Cameroon. The dominant pattern is the transition from the native vegetation (savannahs, gallery forests) to agriculture through firewood exploitation and burning. Cattle production and traditional burn-andtill agriculture are the main land uses in converted areas (MINEF, 1996). Moreover, the low fertility of soils in the region leads to the frequent abandonment of fields to pastures, fallows, and habitable lands. Consequently, the landscape that results from these anthropogenic activities is a mosaic mostly composed of agricultural lands, pastures, and grass, shrub, and woody savannahs. Even if the effects of land use changes on earthworm populations in tropical areas have been studied elsewhere (Decaëns et al., 1994;Fragoso et al., 1999), little information is known about earthworm population dynamics in Cameroon, especially in the Guinean and Sahelian zones in northern Cameroon where rapid soil degradation occurs. In this context, savannahs play a key role in maintaining soil Abstract: Earthworms are present in all types of soil. Changes in land use influence populations of earthworms. However, information on the dynamics of earthworm populations in northern Cameroon is not available. This paper highlights the research carried out on the abundance, biomass, and diversity of earthworm populations throughout four types of land use in northern Cameroon. Earthworms were sampled throughout the rainy season in three regions, across pastures, woody savannahs, grass savannahs, and fields, using formaldehyde and hand sorting. Earthworms of the woody savannah and pasture have a high mean density (63 and 45 individuals/ m 2 , respectively) and biomass (25.2 and 22 g/m 2...

Extended use of glyphosate poses the problem of its accumulation into soil and further on crops. The objective of this study was to evaluate the effects of different doses of soil glyphosate on growth parameters and chlorophyll content of maize Zea mays L. and bean Phaseolus vulgaris L. plants. An experiment was arranged in randomized complete blocks design with ten replications. Glyphosate solutions were applied to the soil in six concentrations, two subdoses of 0.1 and 0.2 g, the recommended dose of 0.4 g and three overdoses of 0.6, 0.8 and 1.0 g kg-1 of soil. An uncontaminated soil control was used. At 21, 28, 35 and 42 days after sowing (DAS), evaluations of plant height, number of leaves, stem diameter, leaf surface and plant injury were conducted. At 42 DAS, nodulation (in bean), root length, chlorophyll and dry matter yield were assessed. Already at the recommended dose and beyond, glyphosate caused significant damage to growth characteristics, nodulation and chlorophyll content in both plants. Some similar effects of the product were observed on the both plants at each time period. Therefore, there was an evidence that soil glyphosate already at the recommended dose had an inhibitory and even a phytocide effects on non-target plants.

In holometabolous insects, life‐history characteristics can vary in response to diet. The main aim of this contribution was to examine which diet best promotes larval development and survival of the aquatic saprophagous hoverfly Eristalis tenax L. (Diptera: Syrphidae). This study was motivated by a need to optimize techniques for rearing these insects in captivity. We studied how adding yeast to several rearing media based on animal droppings or decaying plant material affected development and survival in captive larvae, and whether these effects could be optimized depending on the amount of yeast and the rearing medium. In addition, premature exit of larvae was examined in two medium volumes to investigate differences in pupation. Larvae in yeast supplemented rabbit growth medium pupated and emerged faster than those in horse and antelope growth media. A high number of adult females emerged when compared to males, and both seemed to have a shorter developmental period in yeast supplemented growth media. Pupal survival was significantly greater in a mixture of droppings and plant organic matter, and a high medium volume of 140 ml (p < 0.05). Between 10% and 17% of larvae prematurely exited the aquatic medium in high (140) and low (70 ml) medium volumes, respectively. These results provide additional information that may be crucial for the successful mass rearing of E. tenax in captivity, and suggest that apart from the addition of yeast, growth medium quality and volume may be limiting factors for the production of large colonies of adults.