Impact of the Zoophytophagous Plant Bug <I>Nesidiocoris tenuis</I> (Heteroptera: Miridae) on Tomato Yield

Abstract

Nesidiocoris tenuis Reuter (Heteroptera: Miridae) is one of the most controversial dicyphines because of the injuries it causes to tomato (Solanum esculentum) crops. The aim of this study was to quantify the impact of N. tenuis on fruit yield. Tomato plants were exposed to an average of 0.53 +/- 0.26, 3.4 +/- 1.1, 12.0 +/- 1.4, and 35.2 +/- 7.7 N. tenuis per plant for 3 wk. When fruit were exposed to N. tenuis as flowers, the percentage of aborted fruit was higher in compartments infested with N. tenuis, and this was related directly to the cumulative number of N. tenuis (CNN). However, compartments with the highest abortion rates had heavier and bigger fruit and were not significantly different from the controls. The variation in fruit weight was satisfactorily explained with a logistic equation in relation to the proportion of aborted fruit. To estimate the density thresholds, the variation in truss weight was predicted as a function of fruit weight and aborted fruit. The two latter variables were expressed as a function of the CNN. A maximum of 15% truss weight overcompensation was predicted at 15.8% of fruit abortion. Yield reduction was predicted at fruit abortion rates > or = 27.7%, which corresponded to 566 CNN per plant or 32.11 CNN per leaf. N. tenuis may be considered a useful predator of small pests in tomato crops if kept under these thresholds. Mathematical models predict a yield increase and fruit upgrade that overcompensates for the reduction in the number of fruit below the density threshold.