Author ORCID Identifier

Date Available


Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Arts and Sciences



First Advisor

Dr. Catherine R. Linnen


Group living is found across the animal kingdom ranging from temporary mating aggregations to complex, eusocial lifestyles. A particularly common form of group living found among insects are larval or nymphal herds. This lifestyle consists of immature insects living together and results in several proposed costs and benefits. Benefits of this lifestyle include improved ability to regulate a group’s microenvironment, more efficient use of their host, and the ability to engage in collective predator defenses. Offsetting these benefits are costs resulting from living in close proximity to conspecifics which include increased competition, greater visibility to predators, and heightened disease risks. While evidence for these costs and benefits have been found in many species, they have not appeared consistently across all larval herding species.

In this dissertation, we studied the larvae of a group of pine sawflies (the lecontei group of the genus Neodiprion) to investigate the causes and consequences of the larval herding lifestyle. Neodiprion sawflies are well suited to such study because there is natural variation across the genus in multiple traits including social behaviors and use of a common form of predator defense in larval herding organisms, aposematism. Aposematism is a combination of warning coloration and patterning alongside another form of defense, often of a chemical nature. For Neodiprion, this chemical defense results from the sequestration and regurgitation of resin from their host plants, pine trees (genus Pinus) and occurs in all species.

We describe a quantification of social behavior, aggregative tendency, and used it alongside a more commonly used sociality trait, group size. We also measured a variety of other larval traits and features of their environment. We found that aggregative tendency and group size are distinct traits with their own adaptive roles. Group size was found to be highly related to the egg clutch size oviposited by mothers and, alongside the amount of chemical defense, larger group sizes cause increases in aposematic patterning. Aggregative tendency, however, was found to serve in a mediating role optimizing conditions of group-living given a particular group size. First, it appears to be related to ambient relative humidity serving as a means of water conservation. Second, it was found to be associated with immune activity in a manner implying it can alter group distance as a form of social immunity. These findings were robust for Neodiprion and we believe that they may be generalizable to other larval herding organisms.

Digital Object Identifier (DOI)

Funding Information

Ribble Mini-Grant, University of Kentucky ($700.00) 2017

Graduate Student Research Award, Society of Systematic Biologists ($1500.00) 2015

Academic Year Fellowship (Fall Semester), University of Kentucky 2015

Ribble Mini-Grant, University of Kentucky ($300.00) 2015

SysEB Student Research Travel Award, Entomological Society of America ($1491.00) 2015

Academic Year Fellowship (Fall Semester), University of Kentucky 2014

Daniel R. Reedy Quality Achievement Award, University of Kentucky ($3000.00) 2013

Academic Year Fellowship, University of Kentucky 2013

Flora Ribble Research Fellowship, University of Kentucky ($2000.00) 2013