Toxicity assessment of two IGR insecticides on eggs and larvae of the ladybird Eriopis connexa (Coleoptera: Coccinellidae)

NOELIA, FOGEL MARILINA; SCORSETTI, ANA CLARA; MINARDI, GRACIELA; SCHNEIDER, MARCELA INÉS

PEST MANAGEMENT SCIENCE

JOHN WILEY & SONS LTD

Año: 2022

1526-498X

BACKGROUND: Eriopis connexa is an important predator in the Neotropical region, associated with pests of economic relevance on horticultural crops in Argentina. The use of broad-spectrum insecticides could reduce the biodiversity of these natural enemy at agroecosystems and put in risk the conservation of this predator. New selective insecticides called "risk reduced" could be an alternative to conventional chemical control to promote sustainable agriculture. The goal of this work was to assess lethal and sublethal effects of two IGRs insecticides on E. connexa when eggs and two larval instars of it were exposed to insecticides.RESULTS. Eggs treatment: Pyriproxyfen and cypermethrin significantly affected the egg hatching by 28.8 and 70.4 %, respectively. Pyriproxyfen reduced the survival of larvae that emerged around 52% from the third day after hatching and caused the lengthening of the developmental time of both larval and pupal stages. In contrast, teflubenzuron did not reducehatching and survival but shortened the developmental time of the pupae stage. Second and fourth larval instars treatment: Cypermethrin reduced the survival of second and fourth larval instars between 36.4 and 74.6%, respectively and lengthened the development time of the secondlarval instar. Pyriproxyfen lengthened the development time of the fourth larval instar and reduced fecundity and fertility of females. Teflubenzuron reduced survival of second and fourth larval instar between 46,9 and 28,6% respectively and lengthened the development time for larval stage. In addition, teflubenzuron reduced fecundity and fertility of females.CONCLUSIONS: Both eggs and larvae were susceptible to exposure to IGR, showing lethal effects and sublethal effects. This study highlights, once again, the higher toxicity of cypermethrin to E. connexa. The toxicity of both IGRs insecticides could impair the performance of E. connexa as a biological control agent in agroecosystems.