Wheat fertilization affects oviposition preference of wheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae)

In Canada, the orange wheat blossom midge (hereafter called wheat midge), Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), causes millions of dollars of damage to wheat crops every year. Host plant nutrition directly or indirectly influences insect oviposition owing to their higher food quality. We tested the effect of fertilizer rates (0.5, 1.5, 2.5 g per pot) on plant growth parameters, tissue nitrogen (N) content, protein content, wheat midge oviposition, and larval performance using a susceptible wheat cultivar, 'Roblin'. We also examined the volatile organic compound (VOC) profile in plants grown under different fertilization regimes using thermal desorption comprehensive 2D gas chromatography time-of-flight mass spectrometry (TD-GC × GC-TOFMS) to test whether VOCs are influenced by plant fertilization.

Higher fertilization rates increased plant fresh weight and number of spikes per plant. However, the highest percentage of nitrogen and protein content were observed in the moderate fertilization treatment, followed by the high and low treatments. Wheat midge laid proportionally more eggs in the moderate than in the high fertilization treatments, with intermediate numbers of eggs observed in the low fertilization treatment, in choice oviposition tests. Fertilizer treatments did not affect the total number of wheat midge eggs and larvae, and the average larval weight in no-choice tests. The VOC profile of plants in the moderate and high fertilization treatments differed from that of the low fertilization treatment.

Plant fertilization increases plant growth, nitrogen, and protein levels, alters the VOC profile, and affects female wheat midge oviposition preference. Increased egg-laying may be affected by the observed changes in the VOC profile, which warrants further investigation comparing the effects of fertilization on the VOC profiles of susceptible and oviposition-deterrent wheat varieties. Under no-choice conditions we did not detect fertilization effects on wheat midge oviposition or early development, but future studies should focus on potential effects on adults and their reproduction. These findings provide a deeper understanding of how plant nutrients influence wheat midge-host plant interactions. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.