Predation performance and survival of susceptible and pyrethroid-resistant Eriopis connexa Germar (Coleoptera: Coccinellidae) to insecticides used in brassica crops

Authors: LIRA, ROGERIO - Federal Rural University Of Pernambuco; NASCIMENTO, DEIVIDY - Federal Rural University Of Pernambuco; BARBOSA, PAULO - Federal Rural University Of Pernambuco; Simmons, Alvin; TORRES, JORGE - Federal Rural University Of Pernambuco

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2023
Publication Date: 3/11/2023
Citation: Lira, R., Nascimento, D.V., Barbosa, P.R., Simmons, A.M., Torres, J.B. 2023. Predation performance and survival of susceptible and pyrethroid-resistant Eriopis connexa Germar (Coleoptera: Coccinellidae) to insecticides used in brassica crops. Pest Management Science. 79:2704-2712. https://doi.org/10.1002/ps.7448.
DOI: https://doi.org/10.1002/ps.7448

Interpretive Summary: Insecticides are commonly used as a pest management strategy against pests such as aphids and caterpillars of the diamondback moth in Brassica crops such as collard and kale. Research was conducted to assess10 common insecticides for their compatibility with a lady bug predator in the Brassica cropping system. This study demonstrates that several of the evaluated insecticides (Bacillus thuringiensis, cyantraniliprole, chlorantraniliprole, deltamethrin, chlorfenapyr, spinosad, azadiracthin, and spiromesifen) are compatible with adults of the predator lady bug Eriopis connexa in Brassica crops. Therefore, this natural enemy can have a positive impact on helping to manage pests in the Brassica cropping system when several selected insecticides are used by growers.

Technical Abstract: Selective insecticides and insecticide-resistant natural enemies are chemical and biological methods that can be compatible in an integrated pest management program. Many insecticides that are labeled for treatment against pests in Brassica crops have lost their efficacy because of the development of resistance due to their frequent use by growers. However, natural enemies can provide an important role in regulating the population of these pests. We assessed the mortality of Plutella xylostella (L.) (diamondback moth) and Lipaphis pseudobrassicae (Davis) (turnip aphid) against 10 insecticides labeled to treat pests in Brassica crops, and compared the survival and predation performances of two populations of the predator Eriopis connexa (Germar) when exposed to these insecticides. We used one population of E. connexa that was susceptible (EconSus) and another that was resistant (EconRes) to pyrethroids. For insecticides causing high mortality of adult E. connexa applied at the maximum labeled field rate, lethal concentrations (LCs) were determined allowing the determination of Differential Selectivity Index and the Risk Quotient. Survival of both populations of E. connexa was >80% when exposed to the insecticides, except for exposure with indoxacarb and methomyl (EconSus). Insecticides Bacillus thuringiensis, cyantraniliprole, chlorfenapyr, and spinosad resulted in high mortality of P. xylostella larvae, but were harmless to E. connexa beetles and its predation upon L. pseudobrassicae. Cyantraniliprole, chlorfenapyr, deltamethrin, and methomyl resulted in high mortality of L. pseudobrassicae, but were harmless to E. connexa beetles and did not affect their consumption of P. xylostella larvae. This study demonstrates that the insecticides B. thuringiensis, cyantraniliprole, chlorantraniliprole, deltamethrin, chlorfenapyr, spinosad, azadiracthin, and spiromesifen are compatible with adult E. connexa within an integrated pest control program in Brassica crops and would be accommodating to the conservation of this natural enemy.