Functional response and age-specific foraging behaviour of Necremnus tutae and N. cosmopterix, native natural enemies of the invasive pest Tuta absoluta in Mediterranean area

Abstract

The native parasitoids Necremnus tutae Ribes & Bernardo and N. cosmopterix Ribes & Bernardo (Hymenoptera: Eulophidae) are potential biocontrol agents of the exotic tomato pest Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in Europe. We investigated the functional response of parasitoid females to different densities of 3rd-instar host larvae (from 3 to 40 hosts offered), as well as some life history traits (longevity, lifetime fecundity, parasitism and host-feeding rate) of N. tutae and N. cosmopterix. In functional response experiments, the rate of attack of both parasitoids was positively correlated with host density, N. tutae and N. cosmopterix showing type III and type II functional response, respectively; the latter species exhibited a higher maximum estimated host-killing rate than the former. Both parasitoids showed high fecundity (> 50 eggs) during their lifetime. The potential application of N. tutae and N. cosmopterix in conservation biological control of T. absoluta is discussed.

Appendix

$$N_{a} = \frac{aN}{1 + aN}$$

(1)

Eq. 1 Holling’s type II functional response model.

$$N_{p} = \frac{{aN^{2} }}{{1 + aN^{2} }}$$

(2)

Eq. 2 Holling’s type III functional response model.

$$N_{p} = \frac{{aN^{\theta } }}{{1 + aN^{\theta } }}$$

(3)

Eq. 3 θ-logistic functional response model.

$$y = \left[ {P_{1} \left( {x - P_{2} } \right)} \right]/\left\{ {\exp \left[ {\ln \left( {P_{3} } \right)\left( {x - P_{2} } \right)} \right]} \right\}$$

(4)

Eq.4 Bieri model, where x = age of female (days), and P₁, P₂ and P₃ are coefficients.

$$y = P_{1} (x - x_{min} )^{{P_{2} }} . (x_{max} - x)^{{P_{3} }}$$

(5)

Eq.5 Analytis model, where x = age of female (days), x_min and x_max are the first and final age of oviposition, and P₁, P₂ and P₃ are coefficients.