Duncan Chacha

Duncan Chacha

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Duncan Chacha

CABI, Nairobi, Kenya

Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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13 May 2020 in Pest Management Science
Verified
Journal Article
Open access
PDF file
KCKate L. Constantine
Kate L. Constantine
MKMonica Kansiime
Monica Kansiime
IMIdah Mugambi
Idah Mugambi
WNWinnie Nunda
Winnie Nunda
DCDuncan Chacha
Duncan Chacha
RDRoger Day
Roger Day
Background: Although Kenya has a relatively high number of registered biopesticide products, little is known about biopesticide use by smallholders. This paper documents farmers' current use and perception of chemical pesticides and biopesticides, their willingness to pay for biopesticides, and the key challenges to biopesticide uptake. Results: A survey found that chemical pesticides are used widely by smallholders despite awareness of the risks to human health and the environment. Almost half of respondents showed awareness of biopesticides, but current use in the survey localities was low (10%). Key reasons for the low use of biopesticides by smallholders in this study are: perceptions of effectiveness, primarily speed of action and spectrum of activity, availability and affordability. Smallholders who used biopesticides cited effectiveness, recommendation by advisory services and perception of safety as key reasons for their choice. Although farmers viewed both pesticides and biopesticides as costly, they invested in the former due to their perceived effectiveness. Average willingness to pay, above current chemical pesticide expenditures per cropping season was 9.6% (US$5.7). Willingness to pay differed significantly between counties, and was higher among farmers with more education or greater awareness of the health risks associated with pesticide use. Conclusion: This study confirms the low use of biopesticide products in the survey areas, alongside high use of conventional chemical pesticides. In order to promote greater uptake of biopesticides, addressing farmers' awareness and their perceptions of effectiveness is important, as well as increasing the knowledge of those providing advice and ensuring registered products are available locally at competitive prices. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

25 March 2021 in CABI Agriculture and Bioscience
Verified
Journal Article
Open access
PDF file
ABAlan Buddie
Alan Buddie
IRIvan Rwomushana
Ivan Rwomushana
LOLisa C. Offord
Lisa C. Offord
SKSimeon Kibet
Simeon Kibet
FMFernadis Makale
Fernadis Makale
RDRoger Day
Roger Day
Following reports of an invasive snail causing crop damage in the expansive Mwea irrigation scheme in Kenya, samples of snails and associated egg masses were collected and sent to CABI laboratories in the UK for molecular identification. DNA barcoding analyses using the cytochrome oxidase subunit I gene gave preliminary identification of the snails as Pomacea canaliculata, widely considered to have the potential to be one of the most invasive invertebrates of waterways and irrigation systems worldwide and which is already causing issues throughout much of south-east Asia. To the best of our knowledge, this is the first documented record of P. canaliculata in Kenya, and the first confirmed record of an established population in continental Africa. This timely identification shows the benefit of molecular identification and the need for robust species identifications: even a curated sequence database such as that provided by the Barcoding of Life Data system may require additional checks on the veracity of the underlying identifications. We found that the egg mass tested gave an identical barcode sequence to the adult snails, allowing identifications to be made more rapidly. Part of the nuclear elongation factor 1 alpha gene was sequenced to confirm that the snail was P. canaliculata and not a P. canaliculata/P. maculata interspecies hybrid. Given the impact of this species in Asia, there is need for an assessment of the risk to Africa, and the implementation of an appropriate response in Kenya and elsewhere to manage this new threat to agriculture and the environment.

21 December 2020 in International Journal of Pest Management
Verified
Journal Article
Open access
MKMonica Kansiime
Monica Kansiime
IRIvan Rwomushana
Ivan Rwomushana
IMIdah Mugambi
Idah Mugambi
FMFernadis Makale
Fernadis Makale
JLJulien Lamontagne-Godwin
Julien Lamontagne-Godwin
RDRoger Day
Roger Day
This study quantified crop losses and economic impacts associated with papaya mealybug (Paracoccus marginatus) infestation in Kenya and identified the most important predictors of papaya tree (Carica papaya L.) yield losses through a household survey of 404 farmers. At least 95% male and 88% female respondents correctly identified papaya mealybug. Papaya was the most affected crop by the pest, with 73% of the respondents indicating that a major part (>60%) of their trees was affected. The estimated papaya yield losses due to papaya mealybug were 57%, with an associated annual economic loss of US$3,009 per ha at the farm level and US$29.8 million at the national level. Regression analysis showed significant yield-reducing effects with high infestation levels of papaya mealybug, use of local varieties, and use of indigenous pest control practices. Economic losses differed significantly by county, with the highest losses reported in Mombasa. Male farmers reported higher losses than their female counterparts. Findings highlight the need for location and gender-specific information on pest management for effectiveness in controlling papaya mealybug.

20 July 2023 in Pest Management Science
Verified
Journal Article
Open access
KCKate L. Constantine
Kate L. Constantine
FMFernadis Makale
Fernadis Makale
IMIdah Mugambi
Idah Mugambi
DCDuncan Chacha
Duncan Chacha
HRHarrison Rware
Harrison Rware
FWFrances Williams
Frances Williams
Background: In Kenya, rice (Oryza sativa L.) is mainly produced under irrigation by small‐scale farmers. Mwea irrigation scheme (MIS) in Kirinyaga County accounts for 80–88% of rice production. Here, rice is the main source of livelihood and a source of revenue generation for the county. However, a recently established invasive freshwater snail, Pomacea canaliculata (Lamarck) (family: Ampullariidae), a species of apple snail, presents a serious threat to rice production.Results: Household surveys, focus group discussions and key informant interviews highlight apple snail as a serious problem in MIS. Households that observed at least a moderate level of infestation (>20% of cultivated area) experienced significant reductions in rice yield (~14%) and net rice income (~60%). Farmers reported increased use of chemical pesticides for management of apple snail. In addition, the cost of hired labor for physical removal of egg masses and snails is resulting in substantial negative effects on net income. Farmer age, area of land owned, responsibility for decision‐making, receipt of extension advice, training, and membership of a farmer organization, were all statistically significant variables to explain farmers awareness of the need for area‐wide apple snail management.Conclusion: Strategies to limit the spread of apple snail are urgently needed. A Multi‐Institutional Technical Team (MITT) has been established to spearhead management efforts and consolidate advice to farmers on how to manage apple snail. However, without action to mitigate spread, the consequences could be disastrous for rice production and food security in Kenya, and for other rice growing regions across Africa. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

15 June 2023 in CABI Agriculture and Bioscience
Verified
Journal Article
Open access
PDF file
KCKate Constantine
Kate Constantine
FMFernadis Makale
Fernadis Makale
IMIdah Mugambi
Idah Mugambi
HRHarrison Rware
Harrison Rware
DCDuncan Chacha
Duncan Chacha
FWFrances Williams
Frances Williams
Background: Farmer perceptions are highly important in influencing on-farm pest management decision-making. Biological control is extremely sustainable in the smallholder production context, but in Sub Saharan Africa (SSA) few attempts using this pest control method for arthropod pests have been successful, with one of the key reasons cited as poor involvement of farming communities and extension in the dissemination of information. Although farmers’ knowledge and attitudes are hugely important for the successful implementation of biological control, they are often disregarded. Papaya mealybug (Paracoccus marginatus) (PMB) has rapidly spread and established in suitable areas across Kenya becoming a serious pest. The objective of this study is to determine smallholder farmers’ knowledge, attitudes and practices towards biological control; farmers’ willingness to reduce their chemical pesticide use; and levels of support for a classical biological control initiative for PMB management. Methods: Household surveys were conducted covering 383 farming households (148 women) in four papaya producing counties in Kenya alongside key informant interviews with eight extension agents and thirty agro-dealers, and eight focus group discussions. Results: Although some farmers demonstrated awareness of the concept of biological control they lacked knowledge, experience and technical support from extension or agro-dealers. Reasons for not using biological control included inadequate awareness and concerns over efficacy and safety. Farmers expressed high levels of interest and willingness to support biological control, and were willing to reduce their chemical pesticide use to help conserve, and support the establishment of natural enemies. County, perception of biological as safe, training in IPM and gender were all highly significant factors determining farmers willingness to support biological control. Conclusions: Previously, poor attention has been paid to farmer perceptions and participation in biological control, which has resulted in limited success in developing countries. With high levels of interest and willingness to support biological control, the next step is to engage with farming communities impacted by PMB. By building awareness and capacity, and developing a management plan with farmers that will support the release and establishment of the biological control agent, Acerophagus papayae, long-term, sustainable control of PMB in Kenya is possible.

25 March 2022 in Crop Protection
Verified
Journal Article
Open access
ALAlyssa Lowry
Alyssa Lowry
LDLéna Miss Durocher-Granger
Léna Miss Durocher-Granger
MOMaryLucy Oronje
MaryLucy Oronje
DMDaniel Mutisya
Daniel Mutisya
TMTibonge Mfune
Tibonge Mfune
SMSean T. Murphy
Sean T. Murphy