Do Conspecific Herbivores Track Resource Depletion through Host Phenology-Specific HIPVs?

Abstract

Conspecific herbivores use herbivore-induced plant volatiles (HIPVs) as cues while selecting an optimal site for oviposition. This is to ascertain the availability of nourishment for their progeny so that they get the best chance at survival. In the present study, phytophagous eulophid seed-borer Anselmella kerrichi was significantly (time spent: F 3,40 = 13.12, P < 0.0001; number of entries: F 2,30 = 4.21; P = 0.02) attracted to HIPVs from immature fruits of Java plum, Syzygium cuminii (time spent: 4.77 ± 0.40 min; number of entries: 2.27 ± 0.24) when also given the choice of mature fruits (time spent: 1.76 ± 0.32 min; number of entries: 1.46 ± 0.16), indicating that herbivores can assess re-source depletion from host phenology-specific HIPVs. The chemical cues like α -pinene, β -pinene, (z)-ocimene, undecane, 3,7-dimethyl decane, neo-allo-ocimene, allo-ocimene, ethyl benzoate, 2,6,11-trime¬thyldodecane, α -copaene and β -caryophyllene, which are present in immature fruit volatiles elicited antennal response in a GC-EAD analysis. Olfactometer analyses with the synthetic compounds also revealed that A. kerrichi was significantly attracted to these cues and the synthetic blend composed of the above compounds proved to be much more efficient in attracting female wasps when compared to a natural blend. Field evaluations using the synthetic blend showed that it could attract a significant number of A. kerrichi , indicating the scope of using this blend of synthetic HIPVs as a sustainable IPM tool