Liriomyza bioassay methodology database

ABSTRACT – Liriomyza sativae infestations cause economic losses of up to 30% in horticulture like melons and tomatoes, usually controlled with insecticides. Despite the high risk of evolution of resistance, rare are the works seeking to establish a standardization in the bioassay methodology that detects L. sativae resistance to insecticides. In this way, this work improved existing bioassay methodologies for larvae of L. sativae, seeking to standardize and make it possible to obtain more consistent data on susceptibility. Two populations of L. sativae were evaluated with insecticides by immersing leaf discs (2 cm in diameter) of melon and pork beans. Treated leaf discs containing a larva were transferred to trays (Bioassay tray) and acrylic plates. Bioassays were evaluated after 48 and 72 hours of exposure. The susceptibility parameters varied with exposure, type of arena and host, as well as the mode of action of the insecticides. Bioassays in the Bioassay tray provided greater homogeneity of response compared to acrylic plates. The response concentration curves were more accurate and homogeneous with melon leaves compared to pig bean leaves, presenting LC values well below these latter. Although the two methodologies can be used for toxicological bioassays, however, the use of Bioassay tray showed less economic cost and greater agility in the elaboration. Therefore, the enhancement toxicological bioassay methodology is suggested for Liriomyza species that provides more reproducible and less heterogeneous results, enabling research on susceptibility and monitoring of resistance to insecticides.