Body size and feeding specificity: macrolepidoptera in Britain

Area of Science:

• Ecology
• Zoology
• Entomology

Background:

• A general pattern exists where larger-bodied macrolepidopteran moths exhibit reduced host specificity compared to smaller-bodied species within geographic assemblages.
• Several hypotheses have been proposed to explain this observed pattern, including phylogenetic relationships, latitudinal gradients, range size, environmental buffering, and host association strategies.

Purpose of the Study:

• To investigate and test five proposed ecological and evolutionary mechanisms potentially explaining why large-bodied macrolepidopteran moths are less host-specific than small-bodied species.
• To evaluate the validity of these mechanisms using empirical data from British macrolepidoptera and existing scientific literature.

Main Methods:

• Data analysis of British macrolepidopteran species, focusing on body size and host specificity.
• Literature review to gather supporting or refuting evidence for the proposed mechanisms from broader scientific studies.
• Statistical and comparative analyses to assess the significance of each proposed explanatory mechanism.

Main Results:

• While some underlying assumptions of the tested hypotheses were supported, no single proposed mechanism demonstrated significant explanatory power for the observed pattern.
• The study found no conclusive evidence to support explanations based on phylogenetic relationships, latitudinal gradients, range size, environmental buffering, or endophagous associations.

Conclusions:

• The findings indicate that none of the previously proposed individual mechanisms adequately explain the relationship between body size and host specificity in macrolepidopteran moths.
• The study highlights the need to consider alternative or combined explanations, such as those integrating host quality and host defense mechanisms, to fully understand this ecological pattern.