Abstract:
The zoophytophagous mirid predator Nesidiocoris tenuis and the ectoparasitoid Stenomesius japonicus are important biological
control agents for several agricultural pests including the invasive leafminer, Phthorimaea absoluta, a destructive
pest of Solanaceous crops especially tomato in sub-Saharan Africa. However, little is known about how feeding by N.
tenuis can influence the tritrophic interactions in the tomato plant. Here, we tested the hypothesis that N. tenuis phytophagy
would influence the tritrophic olfactory interactions between the host plant tomato and pest, predator, and parasitoid. In
olfactometer assays, P. absoluta females and N. tenuis adults were both attracted to constitutive volatiles released by
the tomato plant. Whereas females of P. absoluta avoided volatiles released by N. tenuis-infested plants, S. japonicus
females and N. tenuis adults were attracted to the induced volatiles. In coupled gas chromatography-electroantennographic
detection (GC-EAD) recordings of intact and N. tenuis-infested plant volatiles, antennae of P. absoluta and S. japonicus
females both detected eight components, whereas N. tenuis adults detected seven components which were identified
by GC-mass spectrometry (GC-MS) as terpenes and green leaf volatiles (GLVs). Dose-response olfactometer bioassays
revealed that the responses of P. absoluta, N. tenuis, and S. japonicus varied with the composition and concentration of
blends and individual compounds tested from N tenuis-induced volatiles. Females of P. absoluta showed no preference
for an eight-component blend formulated from the individual repellents including hexanal, (Z)-3-hexenyl butanoate, and
δ-elemene identified in the volatiles. On the other hand, S. japonicus females were attracted to an eight-component blend
including the attractants (E)-2-hexenal, (Z)-3-hexenol, methyl salicylate, β-phellandrene, and (E)-caryophyllene. Likewise,
N. tenuis adults were attracted to a seven-component blend including the attractants β-phellandrene, δ-elemene, and (E)-
caryophyllene identified in the volatiles. Our findings suggest that there is potential for the use of terpenes and GLVs to
manage the insects in the tritrophic interaction.
