Plant damage by mirids – are there differences between species?

Abstract: Three species of dicyphine mirids are common in Portuguese greenhouses: Dicyphus cerastii, Nesidiocoris tenuis and Macrolophus pygmaeus, the first two being dominant. Their damage to plants varies in appearance and economic importance. Within the TomBugBite and ASTER projects, we used histological and observational data to: (1) compare the histological damage caused by N. tenuis and D. cerastii; (2) compare the behaviour of D. cerastii and N. tenuis females on tomato plants; (3) assess whether the feeding and probing behaviour of D. cerastii and N. tenuis females changes when exposed to plants previously infested by N. tenuis or D. cerastii compared to a healthy plant; and (4) determine whether females of either species prefer to feed on damaged or healthy plant. For morpho-anatomical observations, insectdamaged plant organs were collected from tomato plants and examined under fluorescence and scanning electron microscopy. For behavioural tests, starved females were placed at the bottom of a cylindrical box containing a plant (either healthy or damaged by mirids), and feeding, probing, foraging, walking, oviposition, out-of-plant and out-of-sight behaviours were recorded for 30 min. Damage caused by N. tenuis was brownish, whereas D. cerastii damage was grey and smaller in size. N. tenuis and D. cerastii did not differ in time spent feeding; however, N. tenuis probed the plant significantly more than D. cerastii. Both species probed more and spent more time feeding on healthy than on attacked plants (no difference between conspecific and heterospecific attacked plants).