Nutritional variations at Nesidiocoris tenuis feeding sites and reciprocal interactions between the mirid and tomato plants

Abstract

AbstractNesidiocoris tenuis (Reuter) (Hemiptera: Miridae) uses a flush‐and‐lacerate feeding strategy producing necrotic rings (NR) at feeding sites in tomato plants. The aim was to investigate the variation in the concentrations of amino acids (aa) and sugars at feeding sites, and its effect on this mirid's life‐history traits and behaviour. The concentration of nutrients was measured in different parts of stems damaged by N. tenuis and mechanically using liquid chromatography. aa concentrations increased below NR; around and above NR, the concentrations of essential and non‐essential aa declined. The concentration of glucose was lower around NR and below. The change in the distribution of aa was similar in NR and mechanically damaged stems, whereas there were no differences in sugar contents. Development time and nymphal mortality were measured on fresh leaflets, leaflets with NR and leaflets plus Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). Without prey, development took longer on NR than on fresh leaflets. Development was quicker and mortality lower on leaflets plus moth eggs. Finally, behavioural events were recorded in fifth‐instar nymphs of N. tenuis in: (i) double‐choice experiments (DCE) using leaflets with and without NR; (ii) DCE using leaflets exposed and non‐previously exposed to nymphs and (iii) fresh tomato leaflets plus Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) nymphs. In (i), feeding events lasted longer at NR sites; in (ii), the behaviour of the nymphs on previously exposed leaflets was not significantly different from fresh leaflets; and in (iii), most of the time was dedicated to prey feeding. The overall results indicate that N. tenuis do not take advantage of the inhibited translocation of nutrients in the phloem. The poorer performance of nymphs on leaflets from plants previously exposed to N. tenuis might be due to a general decrease in the concentration of nutrients or to the activation of plant defences.