Objectives: To (1) assess the strength of evidence for the role of termites in vegetation heterogeneity in African savannas, and (2) identify the mechanisms by which termites induce such heterogeneity. Location: African savannas. Methods: We conducted a review of the literature, a meta-analysis and qualitative systems analysis to identify mechanisms to explain the observed patterns. Results: The review provided evidence for termiteinduced heterogeneity in floristic composition and vegetation patterning in savannas across Africa. Termites induced vegetation heterogeneity directly or indirectly through their nest-building and foraging activities, associated nutrient cycling and their interaction with mammalian herbivores and fire. The literature reviewed indicated that termite mounds essentially act as islands of fertility, which are responsible for ecosystem-level spatial heterogeneity in savannas. This was supported by the meta-analysis, which demonstrated that mounds of Ancistrotermes, Macrotermes, Odontotermes (family Macrotermitinae), Cubitermes (family Termitinae) and Trinervitermes (Nasutitermitinae) are significantly enriched in clay (75%), carbon (16%), total nitrogen (42%), calcium (232%), potassium (306%) and magnesium (154%) compared to the surrounding savanna soil. Conclusions: Termite activity is one of the major factors that induce vegetation patterning in African savannas. The implications of this are discussed and research questions for future studies and modelling efforts are indicated.
Pest management research within the context of agroforestry is in its infancy, and it is often difficult to say when a particular pest justifies investment in research to establish facts. Understanding the potentials and drawbacks of farmers' indigenous ecological knowledge (ethnoecology) may form the basis for constructive collaboration between farmers, agroforestry scientists and extension staff. Therefore, the objectives of the study were to (1) assess farmers' knowledge and perceptions of pests, (2) prioritize pest problems that limit tree planting and maize production based on farmers' own criteria and (3) to identify farmers' indigenous pest management practices for priority pests. Data were collected using community meetings, individual interviews and direct observation by the first author. The farmers involved in this study in eastern Zambia had over ten years of experience, while most of the farmers in Mozambique and parts of southern Malawi were new to agroforestry. Farmers perceived insects as the major causes of tree mortality, followed by drought, bush fires and browsing by livestock. Among the biological constraints to maize production, insects (particularly termites and stalk bores) and weeds (particularly Striga asiatica) were more important in farmers' minds than crop diseases. Fundamentally, the farmers' perception of the causes of tree mortality and crop pests agreed with researchers' perceptions and the literature. Both termite and witch weed problems were associated with low soil quality, and farmers use various indigenous control practices to control these pests. Some farmers did not know the causes of tree mortality, and hence do not take action. Farmer's perception of tree mortality was found to be a function of operator-specific variables such as sex, level of education and years of experience with tree species.
Termites (Order: Isoptera) constitute an integral component of various ecosystems in Africa. Termites are also amongst the most difficult insects to study because of their cryptic behaviour and natural nesting habitat. There are around 2600 species of termites in 280 genera which have been described worldwide and about 39% of the total termite species are found in Africa. Termite identification is crucial to understanding termite distribution and their relationship to climate change. Some termite species are well known pests of agricultural crops, forest trees, wood products and timber-in-service causing considerable damage in Africa. This review paper attempts to collate information on African termite distribution and climate change and highlights some knowledge gaps. Africa is the origin of the termite family of Macrotermitinae. The paper focuses more on economically important termite species in Africa. The use of traditional identification methods coupled with molecular techniques in resolving some of the challenges in termite distribution with particular reference to climate change in Africa are discussed. There is scant information on published literature on the impact of climate change on
Maize is the main food crop that meets the nutritional needs of both humans and livestock in the sub-Saharan African region. Maize crop has in the recent past been threatened by the fall armyworm (Spodoptera frugiperda, J.E Smith) which has caused considerable maize yield losses in the region. Controlling this pest requires knowledge on the time, location and extent of infestation. In addition, the insect pest's abundance and environmental conditions should be predicted as early as possible for integrated pest management to be effective. Consequently, a fall armyworm pheromone trap was deployed as a monitoring tool in the present study. The trap inspection is currently carried out manually every week. The purpose of this paper is to bring automation to the trap. We modify the trap and integrate Internet of Things technologies which include a Raspberry Pi 3 Model B+ microcomputer , Atmel 8-bit AVR microcontroller, 3G cellular modem and various sensors powered with an off-grid solar photovoltaic system to capture real-time fall armyworm moth images, environmental conditions and provide real-time indications of the pest occurrences. The environmental conditions include Geographical Positioning System coordinates, temperature, humidity, wind speed and direction. The captured images together with environmental conditions are uploaded to the cloud server where the image is classified instantly using Google's pre-trained InceptionV3 Machine Learning model. Intended users view captured data including prediction accuracy via a web application. Once this smart technology is adopted, the labour-intensive task of monitoring will reduce while stakeholders shall be provided with a near real-time insight into the FAW situation in the field therefore enabling pro-activeness in their management of such a devastating pest.
The objective of the study was to determine the acaricidal properties of Bobgunnia madagascariensis (Desv.) J.H. Kirkbr. and Wiersema (Leguminosae) against adult Amblyomma variegatum (Fabricius) ticks, using Tephrosia vogelii Hook.f. (Leguminosae) as a positive control. Plant extracts of both were prepared using methanol, acetone and chloroform as extraction solvents. Methanol leaf extracts of T. vogelii (0.014 g) and methanol fruit extracts of B. madagascariensis (0.0062 g) gave the highest mean extraction weights among the plant parts and solvents used. In free contact bioassays, only methanol extracts of the bark and leaf material of T. vogelii and methanol fruit extracts of B. madagascariensis produced 100 % mortality of A. variegatum ticks in 24 h. The acaricidal activity of methanol leaf extracts of T. vogelii persisted for up to 8 days while that of fruit extracts of B. madagascariensis persisted for only 6 days. In topical application bioassays, the toxicity of T. vogelii and B. madagascariensis extracts was found to be significantly different at 95 % confidence level, with B. madagascariensis extracts (LD50 0.030 w/v) being more toxic than T. vogelii extracts (LD50 0.555 w/v). This study has shown that plant extracts of B. madagascariensis and T. vogelii extracts have significant in vitro acaricidal activity against A. variegatum ticks and can thus be considered as alternatives for tick control. Further research is however required on persistence, safety and the required application rates.
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