Tag: pest management
Performance of sesbania sesban infested by the defoliating beetle mesoplatys ochroptera in Zambia
Developing integrated pest management practices against the defoliating beetle Mesoplatys ochroptera is an important aspect of the adoption of Sesbania sesban as an improved fallow species in southern Africa. The effect of defoliation by M.ochroptera on the growth of S. sesban(provenance Kakamega) was studied during 1998–2000 at Msekera Research Station in eastern Zambia. To determine the relationship between M. ochroptera densities and degree of defoliation, potted seedlings were infested manually with different densities of larvae and adults. Infestation of two to three month old seedlings with 5–30 larvae or adults resulted in less than 20% defoliation. Infestation of seedlings with 90–150 larvae(>3 masses of eggs) led to 80–100% and 50–80% defoliation in two and three months old seedlings, respectively. The time of infestation and degree of defoliation that lead to reduction in growth and biomass were determined using simulated (manual) defoliation of one to three months old S. sesban seedlings. Manual removal of 50–100% of the foliage atone and two months after transplanting (MAP) appeared to reduce plant height, basal diameter, primary branches, leaf and wood biomass compared to that done atthree MAP. Removal of 25–50% of the sesbania foliage three months after transplanting apparently leads to overcompensation. In sesbania, compensatory growth occurred when 25–50% of the leaves were defoliated three months after transplanting. Therefore, farmers need to protect sesbania seedlings from defoliation against insects such as M. ochroptera only during the first two months after transplanting.
Farmers’ perceptions of tree mortality, pests and pest management practices in agroforestry in Malawi, Mozambique and Zambia
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.
Pest management in miombo fruit trees
In this review, the available information on pests and diseases of priority miombo fruit tree species based on published literature and current studies, identify gaps and suggest management options are summarized. The pest complex of most wild miombo fruit tree species is not known and there is little, if any, published information on pest biology and population dynamics. The bulk of the information in the following discussion is based on observations from ongoing work in eastern Zambia, southern Malawi, southern Mozambique and Zimbabwe
Low Impact of Fall Armyworm (Spodoptera frugiperda Smith) (Lepidoptera: Noctuidae) Across Smallholder Fields in Malawi and Zambia
Fall armyworm (Spodoptera frugiperda Smith), a serious pest of cereals from the Americas, has spread across sub-Saharan Africa and Asia since 2016, threatening the food security and incomes of millions of smallholder farmers. To measure the impact of S. frugiperda under different management approaches, we established on-farm trials across 12 landscapes (615−1,379 mm mean annual rainfall) in Malawi and Zambia during the 2019/2020 and 2020/2021 seasons. Here we present the results from our conventional tillage, monocrop maize, no pesticide treatment, which served to monitor the background S. frugiperda impact in the absence of control measures. Median plot-level S. frugiperda incidence ranged between 0.00 and 0.52 across landscapes. Considering severe leaf damage (Davis score ≥5), the proportion of affected plants varied between 0.00 and 0.30 at the plot scale, but only 3% of plots had ≥10% severely damaged plants. While incidence and damage severity varied substantially among sites and seasons, our models indicate that they were lower in high tree cover landscapes, in the late season scouting, and in the 2020/2021 season. Yield could not be predicted from S. frugiperda incidence or leaf damage. Our results suggest S. frugiperda impacts may have been overestimated at many sites across sub-Saharan Africa. S. frugiperda incidence and damage declined through the cropping season, indicating that natural mortality factors were limiting populations, and none of our plots were heavily impacted. Long-term S. frugiperda management should be based on Integrated Pest Management (IPM) principles, including minimising the use of chemical pesticides to protect natural enemies.
Major pest and disease identification and management guide for mango, avocado, tamarillo and grevillea
Increasing demand for tree products has led to wide production of exotic and native tree species in forest and agroforestry plans. Pests and diseases incidences are at the same time a growing continental crisis. Diseases spread is accelerated by climate change dynamics and implications are concerning African farmers already challenged by weak intervention capacity, fragmented ecosystems, and porous borders. Impacts may also trigger loss of biodiversity, food crisis and constrain agroforestry adaptations strategies. Field observations in parts of Rwanda and Kenya where mango, tamarillo, avocado and grevillea production is prominent, pest and disease incidence is reducing benefits of these production systems. This guide is therefore intended to provide vital information to help smallholders, extension and rural advisory services identify and mange pest and disease incidence before causing total crop failure. Major pest and diseases found in mango, tamarillo, avocado and grevillea are highlighted and possible management plans to reduce spread and losses are indicated as part of wider strategies to dealing with pest and disease break-outs.
Understanding the impact of fall armyworm (Spodoptera frugiperda J. E. Smith) leaf damage on maize yields
Fall armyworm (Spodoptera frugiperda J. E. Smith), a serious pest of maize and other cereals, recently invaded the Old World potentially threatening the food security and incomes of millions of smallholder farmers. Being able to assess the impacts of a pest on yields is fundamental to developing Integrated Pest Management (IPM) approaches. Hence, working with an early maturing, medium maturing and late maturing variety, we inoculated maize plants with 2nd instar S. frugiperda larvae at V5, V8, V12, VT and R1 growth stages to investigate the effects of FAW induced damage on yield. Different plants were inoculated 0–3 times and larvae were removed after 1 or 2 weeks to generate a wide range of damage profiles. We scored plants for leaf damage at 3, 5 and 7 weeks after emergence (WAE) using the 9 point Davis scale. While at harvest we assessed ear damage (1–9 scale), and recorded plant height and grain yield per plant. We used Structural Equation Models to assess the direct effects of leaf damage on yield and indirect effects via plant height. For the early and medium maturing varieties leaf damage at 3 and 5 WAE, respectively, had significant negative linear effects on grain yield. In the late maturing variety, leaf damage at 7 WAE had an indirect effect on yield through a significant negative linear effect on plant height. However, despite the controlled screenhouse conditions, in all three varieties leaf damage explained less than 3% of the variation in yield at the plant level. Overall, these results indicate that S. frugiperda induced leaf damage has a slight but detectable impact on yield at a specific plant developmental stage, and our models will contribute to the development of decision-support tools for IPM. However, given the low average yields obtained by smallholders in sub-Saharan Africa and the relatively low levels of FAW induced leaf damage recorded in most areas, IPM strategies should focus on interventions aimed at improving plant vigour (e.g. through integrated soil fertility management) and the role of natural enemies, as these are likely to result in greater yield gains at lower cost than a focus on FAW control.
Managing Fall Armyworm: A guide to low cost pest management approaches
Fall armyworm (FAW), scientific name Spodoptera frugiperda Smith, is an invasive pest that first arrived in sub-Saharan Africa in 2016. It is a pest of maize and other cereals, although it can eat many plants, and when it first arrived, fearful of the damage it might wreak, regional governments released millions of USD to purchase and distribute pesticides to farmers. Unfortunately, many of these chemicals were not effective. In addition, there are serious risks to human health and environment from the misuse of chemical pesticides.
Qualitative cost-benefit analysis of using pesticidal plants in smallholder crop protection
Assessing the potential drivers of farmers using pesticidal plants for crop protection is essential for wider adoption. However, few studies have focused on collaborative assessments of the underlying trade-offs when using pesticidal plant extracts for pest control. Smallholder farmers in northern Tanzania involved in farmer driven research assessing pesticidal plants evaluated the costs, benefits, trade-offs and areas for future investment. A questionnaire was used to collect demographic information from 77 farmers and their views on pest problems and crop protection in common bean production. This was followed by small focus group discussions (n = 9) using a participatory framework to elucidate the costs and benefits of adopting pesticidal plant technology. A multiple correspondence analysis showed that pesticidal plant use was associated with men greater than 50 years old, and synthetic pesticide use was associated with younger aged farmers and women. Farmers who used synthetics generally did not report the presence of common pest species found in common bean production, whereas farmers who used pesticidal plants were associated with more frequent reports of pest species. This participatory cost–benefit analysis highlighted that tools and processing challenges were the main costs to using pesticidal plants. The main benefit reported when using pesticidal plants was a general improvement to family health. Farmers expressed overall a positive outcome when using pesticidal plants for crop protection and recommended that future investments focus on improving access to tools and education regarding plant processing and extraction to improve uptake of the technology by smallholder farmers. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Maize diversity for fall armyworm resistance in a warming world
Currently, maize (Zea mays L.) production is under threat from climate change, drought, and pests such as fall armyworm (FAW) [Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)]. Since its first detection outside of its native range in 2016, FAW has spread into 76 nations across Africa and Asia adversely affecting maize production and, in turn, the livelihoods of millions of smallholder farmers. Thus, there is a strong need for the development of cost-effective and biologically based integrated pest management (IPM) practices including host-plant resistance (HPR). However, most of the commercial maize cultivars have lost some defensive traits through selective breeding for yield during domestication. The majority of the commercially cultivated hybrids and cultivars in Asia and Africa are highly susceptible to FAW. Therefore, this review summarizes information about various maize landraces, native germplasm, and crop wild relatives (CWRs) possessing FAW resistance traits and about their potential resistance mechanisms, namely antibiosis, antixenosis, and tolerance. There is clear evidence of FAW resistance acting through diverse mechanisms in several maize landraces, germplasm lines, native populations, and CWRs such as Antigua race, FAW Tuxpeno, Zapalote Chico 2451F, Doce Flor da Serra, FAWCC (C5), CMS 14C, PopG (C2), MpSWCB-4, Mp708, Mp 704, CML 67, and FAW 7050, as well as a few species of teosinte and Tripsacum L. Further, a scheme that outlines strategies and approaches for prebreeding and their introgression into elite cultivars for developing FAW-resistant maize is proposed as a possible way forward.