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New Tools to Assess Carrot Weevil Behavioral Ecology: Still-air Bioassay and Degree-day Activity Model for Ohio

Justus, Emily J
http://rave.ohiolink.edu/etdc/view?acc_num=osu1562155921546993

Abstract Details

2019, Master of Science, Ohio State University, Entomology.
Cryptic dispersal, hidden larvae, and long-lived adult stages are among the characteristics of the weevil group that make them difficult to manage. However, it is well known that weevils rely heavily on chemical cues to find hosts and mates, and indeed these cues have been exploited to monitor populations and inform management decisions. A less known and challenging crop-weevil system that would benefit from the investigation of chemical cues is that of the carrot weevil (Listronotus oregonensis) and its cultivated hosts: carrot, celery, and parsley. The majority of carrot weevil research has focused on population management with insecticides, while investigation of carrot weevil behavior or chemical ecology has lagged behind significantly. To address these knowledge gaps I (1) adapted a still-air bioassay approach to evaluate the role of short-range volatile cues in carrot weevil host-seeking behavior, and (2) developed a preliminary degree-day model to understand the emergence activity of overwintering adults in north central Ohio. I found the still-air bioassay to be successful for evaluating carrot weevil response to host volatile odors. Eighty-eight percent of males and 77% of females exhibited attraction to carrot volatiles in the absence of any visual or tactile cues. Similarly, 87% of males were attracted to parsley volatiles in the absence of other cues; however, only 62% of female weevils responded to the volatiles of parsley. Furthermore, male response to parsley volatiles was significantly stronger than that of females. When weevils were given a choice between carrot root and parsley foliage across three experimental dates, male weevils did not exhibit a preference for either host. Females exhibited the same pattern, with the exception of one experimental date wherein 92% of females preferred carrot volatiles over parsley volatiles. Results from two seasons of monitoring overwintering adult activity in the field revealed a consistent 2:1 male-female ratio of capture in carrot-baited modified-Boivin traps. My preliminary degree-day models predicted 50% cumulative emergence of overwintering adults at ~167 CDD7.0 C in 2017, while cumulative emergence in 2018 was predicted to occur at ~450 CDD7.0 C. Recruitment of overwintering adults to baited traps appeared to be influenced by the presence of overwintered host crops, such that traps placed next to overwintered parsley in 2018 recruited carrot weevils more slowly, but for a longer period of time as compared to traps placed next to empty, previously-infested fields in 2017. Together, my results suggest that volatile cues are integral to carrot weevil host-finding behavior and that males may have a broader response to host volatiles than females. These results also demonstrate that a still-air bioassay approach can be used successfully to discriminate carrot weevil response to host volatile cues presented in a laboratory setting. This knowledge will help inform the development of new behavioral manipulation strategies for carrot weevil management and reduce insecticide use for more sustainable specialty crop production.
Elizabeth Long (Advisor)
65 p.
Entomology
Insect Behavior, Chemical Ecology, Curculionidae

Recommended Citations

Citations

  • Justus, E. J. (2019). New Tools to Assess Carrot Weevil Behavioral Ecology: Still-air Bioassay and Degree-day Activity Model for Ohio [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1562155921546993

    APA Style (7th edition)

  • Justus, Emily. New Tools to Assess Carrot Weevil Behavioral Ecology: Still-air Bioassay and Degree-day Activity Model for Ohio. 2019. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1562155921546993.

    MLA Style (8th edition)

  • Justus, Emily. "New Tools to Assess Carrot Weevil Behavioral Ecology: Still-air Bioassay and Degree-day Activity Model for Ohio." Master's thesis, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1562155921546993

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.