Effect of Cry3Bb1-Expressing Transgenic Corn on Plant-to-Plant Movement by Western Corn Rootworm Larvae (Coleoptera: Chrysomelidae)

Abstract

Dispersal of larvae of the western corn rootworm, Diabrotica virgifera virgifera LeConte, in specific combinations of transgenic corn expressing the Cry3Bb1 protein and nontransgenic, isoline corn was evaluated in a 2-yr field study. In total, 1,500 viable western corn rootworm eggs were infested in each subplot. Each year, plant damage and larval recovery were evaluated among four pedigree combinations (straight transgenic; straight nontransgenic corn; nontransgenic corn with a transgenic central, infested plant; and transgenic corn with a nontransgenic central, infested plant) on six sample dates between egg hatch and pupation. For each subplot, the infested plant, three successive plants down the row (P1, P2, and P3), the closest plant in the adjacent row of the plot, and a control plant were sampled. The number of western corn rootworm larvae recovered from transgenic rootworm-resistant plants adjacent to infested nontransgenic plants was low and not statistically significant in either 2001 or 2002. In 2001, significantly fewer larvae were recovered from transgenic rootworm-resistant plants than from nontransgenic plants when both were adjacent to infested, nontransgenic plants. In 2002, significantly more neonate western corn rootworm larvae were recovered from nontransgenic plants adjacent to infested, transgenic rootworm-resistant plants than nontransgenic plants adjacent to infested, nontransgenic plants on the second sample date. Together, these data imply that both neonate and later instar western corn rootworm larvae prefer nontransgenic roots to transgenic rootworm-resistant roots when a choice is possible. However, when damage to the infested, nontransgenic plant was high, western corn rootworm larvae apparently moved to neighboring transgenic rootworm-resistant plants and caused statistically significant, although only marginally economic, damage on the last sample date in 2001. Implications of these data toward resistance management plan are discussed.

Modeling Larval Survival and Movement to Evaluate Seed Mixtures of Transgenic Corn for Control of Western Corn Rootworm (Coleoptera: Chrysomelidae)

“…The data of Hibbard et al (2005) do not eliminate the uncertainty. Comparing the treatment with all nontransgenic plants to the treatment with a central transgenic plant surrounded by nontransgenic plants, I can try to evaluate the potential repellency of transgenic roots and the probabilities of moving from a plant and directly from hatching.…”

Increased survival of western corn rootworm on transgenic corn within three generations of on-plant greenhouse selection

“…Temperatures in such a greenhouse in late June in Missouri are often 50 -65°C. Under these conditions, larvae leave the hot and drying soil in search of a more suitable environment (12,24). Larvae were captured in water pans below each root ball, and were transferred to 95% ethanol at least twice daily.…”

“…Natural infestation by the southern corn rootworm, D. undecimpunctata howardi Barber, is possible in central Missouri, so the species of each rootworm larva was determined based on the presence or absence of urogomphi on the posterior margin of the anal plate (29). Most, but not all, southern corn rootworm larvae can be detected by this technique (12). The number of WCR larvae recovered and larval dry weight were recorded.…”

Video-tracking and On-plant Tests Show Cry1Ab Resistance Influences Behavior and Survival of Neonate Ostrinia nubilalis Following Exposure to Bt Maize

“…Behavioral responses of arthropods to the plant-incorporated toxins produced by insect-resistant genetically-modified (GM or transgenic) crops also have been investigated for several pest species (Harris et al, 1997 [Epiphyas postvittana (Walker)]; Ramachandran et al, 1998 [Plutella xylostella (L.)]; Parker and Luttrell, 1999 [Heliothis virescens (F.)]). In particular, data on movement of pests (Davis and Onstad, 2000;Hibbard et al, 2005) have been used to guide the development of resistance management plans for pests of insect-resistant transgenic crops (European corn borer, Ostrinia nubilalis Hübner, [U.S. -EPA, 2001] and corn rootworms, Diabrotica spp., [NCR-46, 2001]). However, relatively fewer studies have investigated how pest behavioral responses to insect-resistant transgenic crops are influenced by alleles that confer resistance to plant-incorporated toxins (but see Gould and Anderson, 1991;Schwartz et al, 1991;Harris et al, 2006).…”