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Dzemedzionaite, Vaida, 2021. The effect of gut microbiota and insecticide resistance on host plant preferences and voracity of the cotton fly, Spodoptera littoralis. Second cycle, A2E. Alnarp: SLU, Dept. of Biosystems and Technology (from 130101)



To counteract pesticide resistance development, it is crucial to understand why
and when it evolves. Additionally, to inform the farmers about this term and
provide advices on efficient pest management strategies to prevent pesticide
resistance. An agroecological approach may be suitable since it applies science,
practice and social movements to improve more sustainable food systems by
helping developing pest management strategies.
The main aims of this project were gaining better knowledge about the possible
connection between insecticide resistance development, host plant range and the
effect of gut microbiota and surveying the knowledge among farmers on pesticide
resistance development. The experimentations on the pest, Spodoptera littoralis,
were performed to study if host plant preference and performance with insects that
were either pesticide resistant or susceptible and where the gut microbiota was
damaged while using the antibiotics or intact.
The preference experiments did not show any results of changed host plant
preference or survival rate due to resistance level or gut microbiota status. It was
found that larvae’s initial host plant choice differs from the final choice indicating
that larvae need to feed on the host plant longer to make a choice. However, while
treated with the antibiotics, larvae ate significantly more of the leaves than
unexposed larvae. Just as for the preference experiment, the efficiency of
conversion experiment did not show significant differences in terms of resistance
level or gut microbiota. A significant difference in efficiency of conversion was,
however, found between the host plants where cotton presented higher indices
compared to maize. In addition, larvae gained more weight consuming cotton than
on maize, which indicates that maize is a poor host plant and that the host plant
plays an important role in larval metabolism.
The social science results indicated that farmers from Sweden, Tanzania and
Lithuania are aware of pesticides detrimental effects but still use pesticides very
actively, mainly because of their effectiveness. Tanzanian respondents were the
only ones who have never heard about pesticide resistance while Swedish farmers
presented high knowledge about this process. Better knowledge of pesticide use
and pesticide resistance development need to be introduced to Tanzanian farmers
to prevent the health problems caused by pesticide application. More sustainable
pest management strategies in all the targeted countries are crucial to reduce
pesticide use and pesticide resistance development. To do so, communication
between researchers and farmers – practitioners is needed.

Main title:The effect of gut microbiota and insecticide resistance on host plant preferences and voracity of the cotton fly, Spodoptera littoralis
Authors:Dzemedzionaite, Vaida
Supervisor:Karlsson Green, Kristina and Bras, Audrey
Examiner:Stenberg, Johan A
Volume/Sequential designation:UNSPECIFIED
Year of Publication:2021
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:LM005 Agroecology - Master's programme 120 HEC
Supervising department:(LTJ, LTV) > Dept. of Biosystems and Technology (from 130101)
Keywords:Insecticide resistance, gut microbiota, insect pest, host plant preference, sustainable agriculture
Permanent URL:
Subject. Use of subject categories until 2023-04-30.:Protection of plants - General aspects
Pests of plants
Deposited On:26 Nov 2021 10:37
Metadata Last Modified:27 Nov 2021 02:00

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