Norman Jesse Cone IV is an undergraduate student in the School of Biological Sciences at Louisiana Tech University.
Natalie Clay is an Assistant Professor in School of Biological Sciences at Louisiana Tech University

Clay, Natalie

Cone, Norman J., IV

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Louisiana Tech UniversityLouisiana Tech Digital CommonsANS Research Symposium ANS Research Symposium 2018Apr 12th, 8:30 AM - 11:30 AMTemperature Interaction with Density on theGrowth and Survival of a Common GeneralistButterflyNorman J. Cone IVLouisiana Tech UniversityNatalie ClayLouisiana Tech UniversityFollow this and additional works at: https://digitalcommons.latech.edu/ans-research-symposiumThis Event is brought to you for free and open access by the Conferences and Symposia at Louisiana Tech Digital Commons. It has been accepted forinclusion in ANS Research Symposium by an authorized administrator of Louisiana Tech Digital Commons. For more information, please contactdigitalcommons@latech.edu.Recommended CitationCone, Norman J. IV and Clay, Natalie, "Temperature Interaction with Density on the Growth and Survival of a Common GeneralistButterfly" (2018). ANS Research Symposium. 23.https://digitalcommons.latech.edu/ans-research-symposium/2018/poster-presentations/23 35  Temperature interaction with density on the growth and survival of a common generalist Butterfly  Norman Jesse Cone IV1, Dr. Natalie Clay2 Undergraduate in School of Biological Sciences, Louisiana Tech University1 Assistant Professor in School of Biological Sciences, Louisiana Tech University2 Warming temperatures have the potential to disturb species interactions, organism phenology, and alter the natural ranges of species. Organisms vary in their responses to climate change ranging from no response to range shifts and evolutionary adaptations. Ecototherms, like Lepidopterans (moths and butterflies) are particularly sensitive to changes in temperature. Lepidopterans impact ecosystem productivity because they facilitate pollination, directly impact plant biomass through herbivory, and are prey for higher trophic levels. Many species have large ranges and develop with cohorts of variable densities on host plants. Thus, how different lepidopterans are affected by warming temperatures can have large consequences on ecosystem function. We tested the hypothesis that high temperature and caterpillar densities would accelerate growth and decrease survival. Our hypotheses were first that higher temperature levels would increase growth rates and survival by speeding up metabolic processes, and that caterpillars raised in lower temperatures would have the opposite effect. Second, we hypothesized that higher density levels would increase growth rates through intraspecific competition but also increase mortality. We used painted ladies (Vanessa cardui) to test our predictions due to its widespread range and generalist diet. We setup four treatment groups to test how different densities of lepidopterans would respond to temperature: 1) low density + low temperature, 2) low density + high temperature, 3) high density + low temperature, and 4) high density + high temperature. Temperatures were determined using temperature predictions for the years 2040 – 2059 for Texas and Michigan based on high CO2 emissions, which represent part of the southern and northern range of V. cardui) for the high and low treatments respectively. The density levels for the treatments were taken from lepidopteran density experiments that were based on field observations of cohort size. 2nd instar caterpillars (from Carolina BiologyTM) were reared until pupation or death. We measured mortality and growth rates over 3 weeks. Temperature and caterpillar density impacted both the growth and survival of caterpillars. However, temperature had the largest impact on larval mortality, while density had the largest effect on growth rates. Specifically, increased temperatures correlated with higher larval mortality, and higher population densities corelated with increased growth rates. Contrary to predictions, high temperature had the highest mortality with only 10-20% survival after 1 week compared to 50% in low temperatures. These results suggest that warming temperatures could cause increased mortality in Painted Ladies along their equatorial range. This could result in local extirpation in the southern portion of their current range and an increase in their northern range. Increased growth rates were observed in higher density treatments in the absence of any resource limitation and all other factors were controlled besides density, which suggests that increased population densities innately triggers increased growth rates. One possible explanation for this is that Painted Ladies have evolved plasticity for growth based on larval densities due to typical environmental selection pressures such as competition high larval density in natural habitats. This is also seen in locusts, however more research is needed to determine the mechanism. 

Temperature Interaction with Density on the Growth and Survival of a Common Generalist Butterfly

https://digitalcommons.latech.edu/cgi/viewcontent.cgi?article=1037&context=ans-research-symposium

Temperature Interaction with Density on the Growth and Survival of a Common Generalist Butterfly

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