Is functional response a time-limited response or rather limited by satiation? Case study: multi patch functional response of predatory bug, Nesidiocoris tenuis Reuter (Hem.: Miridae) on eggs of Tuta absoluta Meyrick (Lep.: Gelechiidae).
Functional response is one of the standard criterions to detect the efficiency of a predator as a biocontrol agent. Classic functional response experiments include two fundamental assumptions: (1) the prey is evenly distributed in space; (2) predation rate is often time-limited. In this article, the limiting factor of Nesidiocoris tenuis (Hem.: Miridae) was investigated on tomato leafminer eggs. Multi-patch functional response experiments were carried out using first and fifth instar nymphs and females of the predator. Two set of prey densities exposed to the predator included the upper density or the total number of prey available in all patches equated satiation level. Experiments were conducted by three available times; 1, 2 and 3h for fifth instar nymphs and females, and 1, 1.5 and 2h for the first instar nymphs. The results showed that the predator is limited by volume of its gut rather than by time. The functional response of all stages was from type II. The values of Th and a' were estimated as 4.033 min and 0.0385 min-1 for first instar nymph, 3.517 min and 0.0305 min-1 for fifth instar nymph and 2.512 min and 0.0278 min-1 for female. According to this study, N. tenuis could be considered as an efficient biocontrol agent of tomato leafminer.