This is a Github repository associated with a manuscript on path analysis (structural equation modeling) for using path analyses in integrated pest management or biocontrol research. Target audience for this project are scientists working in applied entomology evaluating field trails, greenhouse experiments, or other surveys. The ideal end-user has already collected data and suspects there are strong direct and indirect effects. Direct effects would be something like biocontrol agent release suppressing and invasive pest, with indirect effects are changes to plant growth resulting from successful biological control.
The authors on this project have applied path analysis (specifically with the piecewiseSEM package in R) to applied entomology projects in forests, agroecosystems, and even molecular ecology. Much of the underlying methods are replicated across these projects and a general interest by students and professionals alike has remained constant over the past 5-6 years.
Among the authors of this paper, an early application was using path analysis to understand the direct and indirect effects of beneficial, predatory ants in forest food webs.
Quantifying the relative role of carpenter ants might not have been elucidated without path analyses, which inspired further research into the role of this ant species a beneficial predator of forest caterpillars.
Read more: Mutualisms mediate ant predatory effects
In another context, path analysis helped to quantify the direct and indirect effects of an aphid vector of pea plant pathogens.
As path models became more complex in this research, it became useful to draw schematics of interaction networks. Interaction network diagrams map out the expected direct and indirection interactions when many potential outcomes were possible. The diagrams informed the starting point for path analysis formally.
Path analysis was useful for showing the effects of non-crop hosts being as strong (or stronger) than the effects of aphid predators like ladybird beetles.
Read more: Tri-trophic ecology of insect vectors
Experimental pest control treatments themslevse have unintended consequences, and these can be examined with path analysis.
Here soil mulching treatments effectively suppressed root-feeding woolly aphids. The application of these treatments slightly increased the root mass of apple trees being protected as well compared to sandy soil conditions.
Read more: Restricting aphid movement between root and canopies