Murray State Theses and Dissertations

Abstract

Insect communication systems are strongly driven by the evolution of signals or signal preferences. These systems rely on a signaler to truthfully emit signals for receivers to interpret. Often, these signals are conspicuously broadcasted. Conspicuous signals involved in animal communication are intended to attract mates, however, these signals are often exploited by eavesdroppers. Thus, many communication systems experience natural selection and sexual selection acting in opposite directions. New adaptations can arise in response to selective pressures, such as eavesdroppers, leading to co-evolving systems between eavesdroppers and hosts, for example. Understanding these systems can provide valuable insight into how unintended receivers can shape the evolution of communication systems. The katydid genus, Neoconocephalus, relies on acoustic communication for mating, whereby males will produce acoustic calls to attract mates. This communication system is exploited by the eavesdropping tachinid fly, Ormia lineifrons, and suffers high levels of parasitism. These parasitoids are a strong selective force on their hosts because they inevitably kill the host within seven to nine days after infestation. The natural history of O. lineifrons and Neoconocephalus sp. interactions lack characterization and is the primary focus of my thesis.

In Kentucky, O. lineifrons is multivoltine and co-occurs throughout multiple Neoconocephalus seasons. Interestingly, four Neoconocephalus species were parasitized by O. lineifrons, three of which are newly discovered hosts. Ormia lineifrons larvae had higher development success rates in N. velox than in N. triops, respectively. Additionally, N. robustus and N. triops pupae were both, on average, significantly heavier than N. velox pupae. As Ormia lineifrons clutch size increased in Neoconocephalus hosts, pupa mass significantly decreased. I found no differences in the mean clutch size or development time of O. lineifrons among the host species. The parasitoid, Ormia lineifrons, imposes selective pressure on multiple Neoconocephalus species in Kentucky. This pressure has the potential to limit the reproductive success for N. triops, N. velox, N. robustus and N. nebrascensis during their breeding seasons. This is the first detailed study outlining the host usage, activity, and development of Ormia lineifrons.

Year manuscript completed

2021

Year degree awarded

2021

Author's Keywords

Parasitism, coevolution, eavesdropping, parasitoid development

Thesis Advisor

Oliver M Beckers

Committee Chair

Christopher J Mecklin

Committee Member

Michael B Flinn

Committee Member

Laura Sullivan-Beckers

Committee Member

Howard Whiteman

Document Type

Thesis

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