Nonadaptive host-use specificity in tropical armored scale insects.

Area of Science:

• Ecology
• Evolutionary Biology
• Entomology

Background:

• Most herbivorous insects are diet specialists, a paradox given the potential benefits of generalism.
• Existing hypotheses suggest fitness trade-offs or nonadaptive evolution via neutral processes and historical constraints.

Purpose of the Study:

• To investigate the adaptiveness of diet specialization in tropical armored scale insects.
• To determine if specialized species exhibit superior performance compared to generalists.

Main Methods:

• Surveyed host use and abundance of hundreds of armored scale insect species across host plants at two tropical sites.
• Analyzed host use patterns and their phylogenetic conservatism.

Main Results:

• Confirmed pervasive diet specialization and phylogenetically conservative host use in armored scale insects.
• Found no evidence that more-specialized species occur on fewer hosts or are more abundant than less-specialized species.
• Observed no performance advantage for specialized species over generalists.

Conclusions:

• The findings challenge the adaptive explanation for insect diet specialization.
• Suggests that specialization in these tropical insects may not be driven by fitness advantages.
• Highlights the need for further research into the evolutionary drivers of specialization.