Pecan [Carya illinoinensis (Wang.) K. Koch] semiochemicals terminate 'diapause' in larvae of Acrobasis nuxvorella Neunzig

Acrobasis nuxvorella Neunzig (pecan nut casebearer=PNC) is a monophagous herbivore of Carya illinoinensis (Wang.) K. Koch (pecan); both are indigenous to North America, where Carya has evolved for ~60 million years. PNC overwinters in diapause as a first instar larva in a hibernaculum attached to a dormant pecan bud. Dormant pecan twigs with hibernacula-infested buds were exposed to a water control or pecan volatiles from Western Schley and monitored to observe larval response using a microcalorimeter in the lab. Metabolic heat produced by overwintering larvae remained low and unchanged when exposed to water vapor and significantly increased within a few hours following exposure to volatiles from extracts of new pecan foliage. Larvae became active and emerged from their hibernacula ~6 d after exposure to Western Schley (90%) and Wichita (80%) volatiles. A subset of sesquiterpenes, from a complex mixture of 111 pecan volatiles, were identified to induce physiological activity. Host volatiles, to our knowledge, have not previously been reported to induce early instar larvae in hibernacula to rouse from a state of physiological arrest to resume normal growth and development. This also has potential for use in pest management.