title: Combined Non-Target Effects of Insecticide and High Temperature on the Parasitoid Bracon nigricans.
abstract: We studied the acute toxicity and the sublethal effects, on reproduction and host-killing activity, of four widely used insecticides on the generalist parasitoid Bracon nigricans (Hymenoptera: Braconidae), a natural enemy of the invasive tomato pest, Tuta absoluta (Lepidoptera: Gelechiidae). Laboratory bioassays were conducted applying maximum insecticide label rates at three constant temperatures, 25, 35 and 40°C, considered as regular, high and very high, respectively. Data on female survival and offspring production were used to calculate population growth indexes as a measure of population recovery after pesticide exposure. Spinetoram caused 80% mortality at 25°C and 100% at higher temperatures, while spinosad caused 100% mortality under all temperature regimes. Cyantraniliprole was slightly toxic to B. nigricans adults in terms of acute toxicity at the three temperatures, while it did not cause any sublethal effects in egg-laying and host-killing activities. The interaction between the two tested factors (insecticide and temperature) significantly influenced the number of eggs laid by the parasitoid, which was the lowest in the case of females exposed to chlorantraniliprole at 35°C. Furthermore, significantly lower B. nigricans demographic growth indexes were estimated for all the insecticides under all temperature conditions, with the exception of chlorantraniliprole at 25°C. Our findings highlight an interaction between high temperatures and insecticide exposure, which suggests a need for including natural stressors, such as temperature, in pesticide risk assessments procedures.
authors.affiliation: High Agronomic Institute of Chott-Mariem, University of Sousse, Tunisia, P.B. 47, 4042 Chott-Mariem, Sousse, Tunisia.
authors.forename: Khaled
authors.initials: K
authors.lastname: Abbes
authors.affiliation: Dipartimento di Agricoltura, University of Catania, Alimentazione e Ambiente, via Santa Sofia 100, Catania, Italy; Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America.
authors.forename: Antonio
authors.initials: A
authors.lastname: Biondi
authors.affiliation: Department of Plant Protection, Agricultural Faculty, Cukurova University, Adana, Turkey.
authors.forename: Alican
authors.initials: A
authors.lastname: Kurtulus
authors.affiliation: Dipartimento di Agricoltura, University of Catania, Alimentazione e Ambiente, via Santa Sofia 100, Catania, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Ricupero
authors.affiliation: Dipartimento di Agricoltura, University of Catania, Alimentazione e Ambiente, via Santa Sofia 100, Catania, Italy.
authors.forename: Agatino
authors.initials: A
authors.lastname: Russo
authors.affiliation: Dipartimento di Agricoltura, University of Catania, Alimentazione e Ambiente, via Santa Sofia 100, Catania, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Siscaro
authors.affiliation: High Agronomic Institute of Chott-Mariem, University of Sousse, Tunisia, P.B. 47, 4042 Chott-Mariem, Sousse, Tunisia.
authors.forename: Brahim
authors.initials: B
authors.lastname: Chermiti
authors.affiliation: Dipartimento di Agricoltura, University of Catania, Alimentazione e Ambiente, via Santa Sofia 100, Catania, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Zappalà
mesh_terms: D000818:Animals; D005260:Female; D006358:Hot Temperature; D006927:Hymenoptera / Q000187:drug effects* / Q000254:growth & development; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects* / Q000254:growth & development; D010572:Pest Control, Biological / Q000379:methods*
chemical_list: D007306:Insecticides