Bracon (Habrobracon) nigricans (Hymenoptera Braconidae) was collected in Italy on Tuta absoluta (Lepidoptera: Gelechiidae), a Neotropical key tomato pest. The parasitoid was successfully reared under laboratory and semi-field conditions for more than fifty generations, with no apparent adverse effects on the parasitoid performances, such as fertility, progeny sex-ratio and parasitization rates. We studied the biology and behaviour of the wasp under laboratory conditions and we documented its life history. Bracon nigricans proved to be a gregarious, idiobiont, arrhenotokous ectoparasitoid of T. absoluta mature larvae. Laboratory studies showed that adults fed on a sugaryproteinic nutrient lived longer and produced more progeny than those provided only with T. absoluta host larvae. The parasitoid progeny was correlated to host densities, and the parasitism rate was higher at lower host densities. Since females should mate multiple times to be able to produce females throughout their life span, progeny sex-ratio mostly depended on male availability. Both females and males were reproductively active soon after emergence. Parasitoid females showed intense stinging activity before effectively starting to lay eggs and/or to feed on the host haemolymph. During this preoviposition activity, female inject venom for permanently paralyzing hosts and very likely for assessing host suitability (based on host size and/or host haemolymphatic kairomone recognition) for the larval development. The proportion of hosts that were killed was constant in all the trials, while the progeny amount was correlated with the host density. Although semi-field and field studies would be needed, the data obtained so far in laboratory conditions suggest that this parasitoid could be considered a potential biological control agent of T. absoluta on tomato in Europe.
Biology and behaviour of the indegenous parasitoid Bracon nigricans on the invasive South American tomato pinworm Tuta absoluta
BIONDI, ANTONIO;SISCARO, Gaetano;ZAPPALA', LUCIA
2012-01-01
Abstract
Bracon (Habrobracon) nigricans (Hymenoptera Braconidae) was collected in Italy on Tuta absoluta (Lepidoptera: Gelechiidae), a Neotropical key tomato pest. The parasitoid was successfully reared under laboratory and semi-field conditions for more than fifty generations, with no apparent adverse effects on the parasitoid performances, such as fertility, progeny sex-ratio and parasitization rates. We studied the biology and behaviour of the wasp under laboratory conditions and we documented its life history. Bracon nigricans proved to be a gregarious, idiobiont, arrhenotokous ectoparasitoid of T. absoluta mature larvae. Laboratory studies showed that adults fed on a sugaryproteinic nutrient lived longer and produced more progeny than those provided only with T. absoluta host larvae. The parasitoid progeny was correlated to host densities, and the parasitism rate was higher at lower host densities. Since females should mate multiple times to be able to produce females throughout their life span, progeny sex-ratio mostly depended on male availability. Both females and males were reproductively active soon after emergence. Parasitoid females showed intense stinging activity before effectively starting to lay eggs and/or to feed on the host haemolymph. During this preoviposition activity, female inject venom for permanently paralyzing hosts and very likely for assessing host suitability (based on host size and/or host haemolymphatic kairomone recognition) for the larval development. The proportion of hosts that were killed was constant in all the trials, while the progeny amount was correlated with the host density. Although semi-field and field studies would be needed, the data obtained so far in laboratory conditions suggest that this parasitoid could be considered a potential biological control agent of T. absoluta on tomato in Europe.File | Dimensione | Formato | |
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