Exposure to a putative insect pheromone primes herbivore induced volatile production in tall goldenrod

Anjel Helms, Penn State

November 6, 2013 @ 12:20 pm to 01:10 pm

102 Forest Resources Building

Olfactory cues play important roles in plant-insect interactions, and especially in plant defense against herbivores. Plants produce characteristic blends of volatile compounds in response to herbivore damage, and previous work has shown that these herbivore-induced plant volatiles (HIPVs) provide olfactory information for insects as well as neighboring plants. Plant volatiles help recruit insect predators and parasitoids that can kill feeding herbivores, and some plants can perceive the odors given off by their insect-damaged neighbors and respond by priming their anti-herbivore defenses. Additionally, we recently discovered that some plants utilize olfactory cues given off directly by their insect herbivores. Our previous work has shown that tall goldenrod Solidago altissima plants exposed to the putative sex attractant of the specialist gall fly Eurosta solidaginis exhibit enhanced anti-herbivore defenses, including reduced palatability and stronger induction of the defense phytohormone jasmonic acid. Here, we demonstrate that exposure to the E. solidaginis emission also primes herbivore-induced volatile production in S. altissima. This phenomenon appears to occur between co-evolved plant and insect species, as we did not observe any evidence of priming in non-host maize plants (Zea mays) exposed to the E. solidaginis emission. Our results also provide further evidence against the possible alternative explanation for reduced damage to S. altissima plants exposed to E. solidaginis that the emission is directly deterrent to feeding herbivores. We found no evidence that emission-exposed squash (Cucurbita pepo) plants repelled herbivores or were less palatable than unexposed plants. Together these results indicate that S. altissima plants respond physiologically to the emission of a co-evolved insect herbivore and that the emission triggers host-plant defenses, but does not appear to be directly deterrent to insects.

Contact

David Watts
daw300@psu.edu