Ecotoxicological Effects of Imidacloprid and Lambda-Cyhalothrin (Insecticide) on Tadpoles of the African Common Toad, Amietophrynus Regularis (Reuss, 1833) (Amphibia: Bufonidae)

Agriculture is the main activity carried out in Cameroon and pesticide use is believed to be a common rule for its success. Most of the farms are situated close to water bodies, thus constituting a potential risk to non-target aquatic organisms. Declines of amphibian populations have been a worldwide issue of concern for the scientific community during the last several decades. The aim of this study was to assess the effects of an insecticide used by local farmers in Buea on amphibians. Parastar 40WP® which is constituted of imidacloprid + lambda-cyhalothrin a commonly used insecticide was applied on tadpoles of the African common toad Amietophrynus regularis (Reuss, 1833) in a static renewal experiment. The acute toxicity test was carried out after a range finding test from which seven test concentrations were selected. These concentrations were 0.0025mg/l, 0.005mg/l, 0.01mg/l, 0.05mg/l, 0.1mg/l, 0.5mg/l and 0.2mg/l. Signs of toxicity such as hyperactive symptoms, loss of balance, motionlessness and death were recorded. A varying degree of mortality (dose-dependent) was noticed during the test. On the contrary, no such toxicity signs and mortality occurred in the control, indicating that they were caused by the test substance. The 24h LC50 was 3.66mg/l, which is less than the recommended application dose (125mg/l). Products constituted of imidacloprid and lambda-cyhalothrin should therefore be handled with care and far from water bodies because of their potential to cause harm to non-target aquatic biota

Environmental and Human Health Assessment in Relation to Pesticide Use by Local Farmers and the Cameroon Development Corporation (CDC), Fako Division, South-West Cameroon

Pesticides are widely used to reduce crop losses due to pests. This study (an initial part of a project on risk assessment and biomonitoring) deals with pesticide use patterns in the South-West, Cameroon. This descriptive and cross-sectional study was done using questionnaires randomly administered to 137 respondents. Twenty-one crops were recorded in the area with a total of 107 pesticides (60 active ingredients) used. Three illegally used pesticides were recorded (lindane, dimethoate and malathion). Application of pesticides in combination was quite common (42.3%). Pesticide application was mainly manual using a sprayer (96.4%) with 54% of users experiencing health problems post-application. Because of the lack of funding and training, 19.7% sprayed pesticides without protection. For the Restricted Entry Interval (REI), 43.1% entered the field in less than 12h after pesticide application. The correlation between the REI and the number of symptoms was negative and non-significant (R=-0.07, p≥0.05). The main place to store pesticides was the house (57.7%) with the exception of CDC where pesticides were kept in a pesticide store. Some respondents (54.7%) said they hadn’t received any training on pesticide application while 20.4 % of respondents failed to follow recommended doses. Surface water around farms was used by 62.1% of pesticides users for domestic purposes. Some farmers (46.7%) have once heard about pesticide related accident while 14.6% suffered from pesticide intoxication, the prevalence being significantly higher in males (p<0.05). Therefore, there is a need to regulate the pesticides sector, assess ecological risk and the bioaccumulation potential of these pesticides as well as their ability to hindrance water quality and biota

Impact De L’exploitation Artisanale De La Sabliere De Toutsang Sur La Structure Des Communautes De Macroinvertebres Du Cours D’eau Doulahang A Dschang (Ouest Cameroun)

The impact of wastewaters from the Toutsang sandpit (Dschang), both on water parameters and on benthic macro-invertebrate community structure of the Doulahang stream was studied from March 2015 to February 2016 on a monthly basis in three sampling stations named TS1, TS2 and TS3. The physico-chemical analysis were carried out according to standard protocols while the benthic macro-fauna was harvested using a haze net of 30 cm side and 400 μm mesh size. The analysis of physico-chemical parameters revealed that the introduction of wastewater from the sandpit at the TS2 station led to an increase of the temperature, conductivity, total dissolved solids, salinity, suspended matter, turbidity and colour. The wildlife inventory identified 63 taxa divided into 4 phyla, 6 classes, 13 orders and 31 families. The lowest values of the taxonomic richness (18 taxa, against 46 taxa and 47 taxa respectively to stations TS1 and TS3), the Shannon diversity index (2.48 bits / ind.) and the Pielou's evenness (0.62) were observed at station TS2 which received wastewaters from the sandpit. Similarly, the low values of the richness and abundance of the pollutionsensitive groups (Ephemeroptera-Trichoptera-Odonata) were recorded in this station. Significant negative correlations were found between some metrics (total taxonomic richness, taxonomic richness of the Diptera, Richness of Ephemeroptera-Trichoptera-Odonata, Taxonomic richness of insects, Relative abundance of Ephemeroptera-Trichoptera-Odonata, Shannon Weaver diversity index, Pielou's evenness) descriptors of the structure of benthic macro-fauna communities and physico-chemical parameters indicative of physical pollution such as turbidity, suspended matter and colour

Bioévaluation De La Qualité Des Eaux Du Cours D’eau Menoua En Zone Périurbaine De Dschang, Ouest Cameroun

We conducted a study to assess the impact of peri-urban agricultural activities of the city of Dschang on the water quality and macroinvertebrate structure of the Menoua stream. This study covered 3 stations (one reference station at the upstream of the peri-urban agricultural activities and two downstream) with a monthly sampling frequency from March 2015 to February 2016. The physico-chemical analysis were carried out according to standard protocols while the benthic macro-fauna was harvested using a haze net of 30 cm side and 400 μm mesh size. Physico-chemical parameters such as temperature, pH, conductivity, TDS (Total Dissolved Solids), salinity, turbidity, colour, SS (Suspended Solids), nitrate, ammonium and orthophosphate were analyzed. The inventory of benthic macroinvertebrates revealed a taxonomic richness of 42 families and 77 taxa and a gross abundance of 1833 individuals. Spatio-temporal monitoring of physicochemical and biological parameters provided the image of relatively low pollution. Metrics such as total taxonomic richness, richness of ETO (Ephemeroptera-Trichoptera-Odonata), relative abundance of Ephemeroptera-Trichoptera-Odonate (% ETO), diversity of Shannon and Weaver and Pielou's equitability were determined at each of the three stations. These indices, unlike several other studies, increased downstream of anthropogenic activities. Low agricultural activity in the watershed has resulted in habitat diversification and availability of resources for benthic macroinvertebrates, resulting in increased abundance and diversit

Assessment of Chemical Pollution With Routine Pesticides Using PRIMET, a Pesticide Risk Model in the Benoe Stream in the South-West Region of Cameroon

Widespread extensive and improper application of pesticides may pose risk to aquatic ecosystem and affect non-target organisms. This study aimed at assessing chemical pollution with pesticides using the PRIMET (Pesticides Risks in the tropics to Man, Environment and Trade) model in the Benoe stream. Ecotoxicological data on pesticides, pesticide and water physico-chemistry were used as input parameters. Water parameters were measured monthly for 06 months in 08 sampling points along the stream. Pesticide characteristics were obtained from the Pesticides Properties Data Base (PPDB) and the PRIMET software. The risk assessment was done for 44 active ingredients used in the area and whose ecotoxicological and physico-chemical data were available. Water parameters significantly (p<0.05) varied across seasons. Based on the Exposure Toxicity Ratio (ETR) and the Predicted Exposure Concentration (PEC), the model predicted 09 pesticides to pose a definite acute risk (ETR>100), seven to pose an acute possible risk (1≤ETR≤100) and 28 to pose no risk (ETR<1). Cadusafos (ETR=5200, PEC=39µg/l) was the most risky pesticide while imazalil (ETR=0.0002, PEC=0.0053µg/l) was the least risky compound. Cypermethrin was predicted to pose both definite acute risk to water and possible chronic risk to fish, water and Daphnia. Seven active ingredients were predicted to pose possible chronic risk to Daphnia. Pesticide used in plantations near water bodies is a threat to the aquatic ecosystem augmented in case of misuse. Bioaccumulation potential and impact of these compounds on water quality and biota community structure should be examined

Prevalence of ectoparasites of the barn swallow (Hirundo rustica) in the town of Dschang, West Region, Cameroon

To estimate the prevalence of ectoparasites of the barn swallow (H. rustica) in Dschang and to see if this bird can be a risk to public health, an investigation was carried out in three sites. An analysis of 51 swallows showed that 35.29% of these birds carry at least one species of ectoparasite. Four species were identified, with the following prevalence: 31.37% (Eomenacanthus stramineus), 5.88% (Goniocotes gallinae), 3.92% (Menacanthus cornutus) and 3.92% (Menopon gallinae). The only significant difference in prevalence between sites was observed with E. stramineus and G. gallinae. Sex did not influence the prevalence of ectoparasites. Swallows of low weight were the most infested. The diversity of nest building material is an indicator of the exploration of several types of media for nest building. Diversity and equitability indexes were 1.05 and 0.53, respectively. A survey carried out using questionnaires showed that swallows are consumed by 30% of the respondents and are used in traditional medicines. These interactions can pose risks to the human population, although we did not find any zoonotic species