Behavioral and physiological responses of susceptible and resistant diamondback moth larvae to Bacillus thuringiensis

Abstract

To determine whether field‐selected resistance of diamondback moth (Plutella xylostella L.) (Lepidoptera: Plutellidae) to Bacillus thuringiensis is based on behavioral or physiological adaptation, we measured mortality, consumption, and movement of larvae from a susceptible and a resistant colony when placed on untreated and B. thuringiensis treated cabbage. Colonies did not differ in mortality, consumption, or movement on untreated cabbage. However, for a given amount of consumption of treated cabbage, resistant larvae had lower mortality than susceptible larvae, demonstrating that resistance had a physiological basis. The movement patterns could not account for the differences between colonies in survival. Resistant larvae did not avoid B. thuringiensis more than did susceptible larvae. Thus, we found no evidence for behavioral resistance.

BACILLUS THURINGIENSIS USE IN AGRICULTURE: A MOLECULAR PERSPECTIVE

“…xylostella obtained fewer total matings than did susceptible males (Groeters et al ., 1993). Schwartz, Tabashnik & Johnson (1991) found no evidence for behavioural resistance in larvae from field-selected, B.t.-resistant populations of P . xylostella collected from a watercress farm on Hawaii, however, the possibility of behavioural avoidance mechanisms in adults was not excluded.…”

Diamondback moth compensatory consumption of protease inhibitor‐transformed plants

“…Though we do not know why PI2 had this consequence on plants with Bt , we propose the following hypothesis. Diamondback moths do not distinguish behaviourally between Bt ‐treated leaves and untreated leaves, and consume both equally readily (Schwartz et al . 1991).…”

<I>Bacillus thuringiensis</I> Resistance Influences European Corn Borer (Lepidoptera: Crambidae) Larval Behavior After Exposure to Cry1Ab

“…Similar behavioral responses that include increased movement often have been observed for other lepidopteran larvae on Bt plants (Ramachandran et al 1998 Schwartz et al 1991, Berdegué et al 1996, Huang et al 2001, and Harris et al 2006, with only one study (Huang et al 2001) including O. nubilalis, the primary lepidopteran target of Bt corn. Given the increasing availability of laboratory-selected pests resistant to Bt toxins (for O. nubilalis, see Siqueira et al 2004, Siegfried et al 2007, opportunities exist to contribute to Bt resistance management by understanding the possible effects of resistance on pest behavior.…”