Larvae with their ventral eversible gland blocked were unable to create furrows and suffered reduced growth on poinsettia.
David E Dussourd 2015, 'Theroa zethus Caterpillars Use Acid Secretion of Anti-Predator Gland to Deactivate Plant Defense.', PLoS ONE
They showed reduced growth and survival suggesting recessive load or overdominance.
Otto Seppälä, Laura Langeloh 2016, 'Estimating Genetic and Maternal Effects Determining Variation in Immune Function of a Mixed-Mating Snail', PLOS ONE