Decrease in tolerance to fenvalerate, in resistant Helicoverpa armigera after pupal diapause

Abstract

Pyrethroid resistant and susceptible adults of Helicoverpa armigera (Lepidoptera: Noctuidae) were screened for tolerance to pyrethroids after 6 wk or 12 wk pupal diapuse. Resistant larvae and F2 larvae from a cross between resistant and susceptible parents (two replicates), were reared under conditions to induce pupal diapause. After eclosion, adults were tested in glass vials coated with the pyrethroid fenvalerate, at a dose (DD) that is known to discriminate between susceptible and heterozygous resistant individuals. In all diapause experiments, the frequency of resistance was lower in the test groups that had experienced diapause compared with the non‐diapausing control group. The underlying cause of the decline is not certain but selective mortality of resistant versus susceptible individuals could not account for all the difference in two of the three experiments ‐ tolerance to the pyrethroid, fenvalerate, is most likely to have declined either as a consequence of diapause or from the extended time of development associated with diapause. These results indicate that monitoring programs could underestimate pyrethroid resistance frequencies when using H. armigera adults emerging from diapause.

Relative Fitness of Cry1A-Resistant and -Susceptible <I>Helicoverpa armigera</I> (Lepidoptera: Noctuidae) on Conventional and Transgenic Cotton

“…A Þt-ness cost associated with overwintering also has been observed in Bt-resistant strains of P. gossypiella (Carriè re et al 2001b) and Colorado potato beetle, Leptinotarsa decemlineata (Say) (Alyokhin and Ferro 1999). A reduction in Þtness has been suggested as a possible explanation for a decline in the frequency of pyrethroid resistance in H. armigera that had experienced laboratory-induced diapause (Daly and Fisk 1995) as well as in overwintering Þeld populations (Daly and Fitt 1990). Reduced Þtness also has been demonstrated in dieldrin-and diazinon-resistant Lucilia cuprina (Wiedemann) that have undergone pupal diapause (McKenzie 1990(McKenzie , 1994.…”

Egg production in response to combined alternative foods by the predator Coccinella transversalis

“…Larvae of H. armigera were obtained from a laboratory colony maintained on artificial diet (Daly & Fisk, 1995). These females were provided experimental diets, which in some instances included larvae of Helicoverpa armigera and/or pea aphid honeydew.…”

“…These females were provided experimental diets, which in some instances included larvae of Helicoverpa armigera and/or pea aphid honeydew. Larvae of H. armigera were obtained from a laboratory colony maintained on artificial diet (Daly & Fisk, 1995). Fresh aphid honeydew was provided each day by previously placing opened petri dishes for 24-48 h beneath bean plants infested with aphids.…”

Pyrethroid and carbamate resistance in Australian Helicoverpa armigera (Lepidoptera: Noctuidae) from 2008 to 2015: what has changed since the introduction of Bt cotton?

“…Furthermore, without a sequence of suitable hosts for cohorts from sorghum to move into, the suppressive effect from Bollgard II® acting as a sink for the H. armigera population may have been compounded by bottlenecking events in years with low rainfall. The abundance of H. armigera may have also been impacted by an increased abundance of natural enemies such as pupal parasitoids due to reduced insecticide use in cotton (Baker & Tann, 2014) or selective mortality due to lower fitness of pyrethroid-resistant individuals following pupal diapause (Daly & Fisk, 1995).…”