Selectivity and Sublethal Effects of Botanical Extracts to Pupae of Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae)

Abstract

Aims: assess the effect of botanical extracts on pupae of the natural enemy Trichogramma pretiosum.
 Study Design: evaluation of the selectivity and sublethal effect on T. pretiosum pupae.
 Place and Duration of Study: Departamento de Proteção Vegetal e Horticultura da Faculdade de Ciências Agronômicas – Universidade Estadual Paulista ¨Júlio de Mesquita Filho¨ (FCA/UNESP) – Campus de Botucatu, São Paulo, Brazil, carried out between March 2016 and April 2017.
 Methodology: the experiment was conducted in laboratory, with eleven treatments: Rosmarinus officinalis, Mikania glomerata, Varronia curassavica, Chenopodium ambrosioides, Vermonia polyanthes, Plectranthus amboinicus, Tetradenia riparia, Artemisia absinthium, Cymbopogon citratus, distilled water and chlorpyrifos, with the two last ones being the negative and positive controls, respectively. The plants were collected in the morning and had 100 g of each species separated and immersed in 300 ml of methyl alcohol for 24 hours in triple extraction. Posteriorly, the solvent was evaporated in rotavapor and the crude extract diluted in the proportion of 1000 mg to 250 mL of distilled water. The parasitism (%) was evaluated. The mortality of the parasitoids was classified in: class 1 – innocuous (E < 30%); class 2 – slightly harmful (30 ≤ E ≤ 79%); class 3 – moderately harmful (80 ≤ E ≤ 99%); class 4 – harmful (E > 99%); daily and accumulated parasitism, total of parasitized eggs and longevity were reported.
 Results: Solely the extract of R. officinalis was selective to T. pretiosum pupae. Despite it, all tested extracts induced sublethal effects, with R. officinalis and C. citratus causing the highest damage. Although R. officinalis resulted in sublethal effects, it was the only extract which did not lead to the mortality of females of T. pretiosum.
 Conclusion: the tested botanical extracts are innocuous (class 1) or slightly harmful (class 2) to pupae of T. pretiosum, resulting in some sublethal effect that might spoil its efficiency in the Integrated Pest Control.