Author ORCID Identifier

https://orcid.org/0009-0001-4963-0084

Date Available

7-9-2024

Year of Publication

2024

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Agriculture, Food and Environment

Department/School/Program

Entomology

First Advisor

Dr. Ricardo Bessin

Abstract

This thesis investigates the efficacy of exclusion netting and selected biopesticides in controlling the common brassica pest harlequin bug (Murgantia histrionica); it assesses the phytotoxic effects caused by selected essential oil products; and it evaluates whether selected treatments caused mortality in common beneficial insects. This is one of the first studies to investigate the potential pest controlling properties of commercially produced bokashi fermented composting products as well as their effect on natural enemies.

During both the first and second year of the study, none of the commercially produced essential oil products or bokashi products were effective in controlling harlequin bug or preventing leaf scars. Conversely, ProtekNet consistently provided the highest level of protection against harlequin bugs of all stages as well as leaf damage scars; it also had the largest broccoli head width and highest yield. However, although ProtekNet effectively excluded harlequin bugs, it also excluded natural enemies which allowed secondary pests such as imported cabbageworm and cabbage aphids to establish. Entrust showed similar results compared to ProtekNet, both with the control of harlequin bug life stages and with leaf scars. These findings suggest that there are multiple effective organic alternatives for this pest as well as varying options for farmers rather than the use of conventional insecticides.

There was also a strong positive correlation between the application of essential oils and phytotoxicity. Essential oil treatments can undoubtedly cause phytotoxic effects on both broccoli and cauliflower plants, even when applied at concentrations listed on the label. These effects can be mitigated by adjusting to lower concentrations. However, the process of implementing essential oils in broccoli and cauliflower fields is still one of trial and error where the risk often outweighs the potential reward. Phytotoxicity did not significantly affect plant growth, head width, or yield in this study suggesting that there is a certain damage threshold that plants can successfully endure. Nevertheless, it is still advisable to exercise caution with these products when incorporating them into a regular treatment schedule.

Finally, the results of this study indicated varying levels of risk for lady beetle (Hippodamia convergens), minute pirate bug (Orius insidiosus), and lacewing larvae (Chrysoperla rufilabris) when using selected essential oil products as well as bokashi fermented products. In summary, the effects of essential oils on beneficial insects are complex and context dependent. These effects can vary depending on factors such as the specific type of essential oil, concentration, application method, and the insect species involved. While this thesis contributes to the understanding of the effect of essential oils and other organic pesticides on harlequin bug, more research will be necessary to determine the implications these treatments have on other insects as well as on larger-scale farm operations.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2024.252

Funding Information

This research was partially funded by the Kentucky Department of Agriculture Specialty Crop Block Grant (PON2 035 2300001318 202202261312).

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CLARK_DATASETS.zip (31 kB)
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