Phytoparasitica (2016) 44, 631-640

Jaconias E. Lima Neto, Marcelo H.P. Amaral, Herbert A.A. Siqueira, Reginaldo Barros and Paolo A.F. Silva (2016)
Resistance monitoring of Plutella xylostella (L.) (Lepidoptera: Plutellidae) to risk-reduced insecticides and cross resistance to spinetoram
Phytoparasitica 44 (5), 631-640
Abstract: The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) is the major pest of the Brassicaceae family. In the Agreste region of Pernambuco (Brazil), a Brassica producing center, P. xylostella is under continuous selection pressure by insecticides leading to increased frequency of resistance genes in this species. The objective of the present study was to monitor the resistance of P. xylostella populations to spinosad, chlorfenapyr, and chlorantraniliprole as well as the susceptibility to spinetoram in the Agreste region of Pernambuco (Brazil). Concentration-response bioassays were performed with spinosad, chlorfenapyr and spinetoram to estimate the LC values. Furthermore, a concentration corresponding to label dose for registered products (chlorantraniliprole, spinosad, and chlorfenapyr) and diagnostic concentration for chlorantraniliprole and spinosad were used. The LC₅₀ to spinosad varied from 0.017 (Recife) to 3.64 (Bezerros II) mg a. i./L (RR₅₀ varying up to ~200-fold), while for spinetoram, they varied from 0.0013 (Alegre) to 0.198 (Bezerros II) mg a. i./L (RR₅₀ varying up to ~150-fold). The LC₅₀ for chlorfenapyr ranged from 0.43 (Recife) to 42.23 (Bezerros II) mg a. i./L (RR₅₀ varying up to ~100-fold). Plutella xylostella populations developed resistance to chlorfenapyr and spinosad. Apparently, there was no alteration of the resistance levels to chlorantraniliprole in the field. Cross-resistance between spinosad and spinetoram (RR₅₀ ~ 150-fold) as well as between the spinosyns and chlorfenapyr was observed. The field populations were susceptible to concentration corresponding to label doses of spinosad (mortality > 80 %) and chlorfenapyr (mortality > 80 %), but a considerable loss of susceptibility to both insecticides was observed. Immediate attention to correct rotation of products is necessary to delay development of resistance in this pest.
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Link to article at publishers website
Database assignments for author(s): Herbert A.A. Siqueira

Research topic(s) for pests/diseases/weeds:
pesticide resistance of pest

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Plutella xylostella		Brazil (NE)