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conferenceseries.com
11th World Congress on
March 05-07, 2018 | Paris, France
Plant Biotechnology and Agriculture
Volume 6 Advances in Crop Science and Technology
ISSN: 2329-8863 Agri World 2018
March 05-07, 2018
Farmer’s decision making toolbox for Plutella xylostella (L.) (Lepidoptera: Plutellidae) management on
fresh market cabbage
Mxolisi Arnold Stemele
Fort Hare University, South Africa
Statement of the Problem: In absence of the pest economic thresholds, farmers apply insecticides prophylactically based on calendar-
sprays with no regard to pest density. In addition, there tends to be no clear guidelines for the integration of the insecticides with
the natural pest control. Consequently, the impact of the insecticides on Biological Control (BC) agents (compatibility), the impact
of the BC agents on the pest (levels of parasitism), seasonality of pest and BC agent’s populations and the action thresholds (weekly
counts) of the insect pests are not taken into account in pest management decision making. This practice constitutes a major threat
to biodiversity in agroecosystem and the surrounding environments.
Methods: Population dynamics of Plutella xylostella, an important insect pest of cabbage and its dominant parasitoid, Cotesia vestalis
(=plutellae) were investigated on cabbage treated with conventional and a selective insecticide under three insecticide treatment
routines. The data was used to develop a simple framework to develop insect pest thresholds and estimate yields through integration
of insect density, yield loss ratios, technical efficiencies and damage abetment factors. In addition, the impact of a conventional and a
selective insecticide on the BC agents was investigated.
Findings: Plutella xylostella populations varied between the seasons, the conventional and a selective insecticide and the insecticide
treatment routines. P. xylostella incidence correlated well with the effective yields and the mean action threshold for the optimal
cabbage yields was estimated at as single larvae per plant. Parasitism of P. xylostella was higher in insecticide free and selective
insecticide treated crop compared to conventional insecticides.
Conclusion: The results indicated that, while cabbage cannot be cultivated without applications of insecticide against P. xylostella
during certain periods of the year, adoption of action thresholds reduce number of sprays. In addition, application of selective
insecticides reduces the insecticides impact on the parasitoids population.
Biography
Mxolisi Arnold Stemele is an Entomology Lecturer at the University of Fort Hare, Eastern Cape, South Africa. His research interest includes biological control,
host plant resistance, toxicology, insect-plant interaction chemical ecology, insect pathology and molecular approaches in entomological research. He is currently
working on a project ‘Decision making tools for farmers in pest management’ and ‘Molecular characterization and DNA barcoding of the Lepidoptera stem borers
on cereal crops and natural vegetation’.
Mxolisi Arnold Stemele, Adv Crop Sci Tech 2018, Volume 6
DOI: 10.4172/2329-8863-C1-005