Intercrop movement of convergent lady beetle, Hippodamia convergens (Coleoptera: Coccinellidae), between adjacent cotton and alfalfa.

A 2-year study was conducted to characterize the intercrop movement of convergent lady beetle, Hippodamia convergens Guerin-Meneville (Coleoptera: Coccinellidae) between adjacent cotton and alfalfa. A dual protein-marking method was used to assess the intercrop movement of the lady beetles in each crop. In turns field collected lady beetles in each crop were assayed by protein specific ELISA to quantify the movement of beetles between the crops. Results indicated that a high percentage of convergent lady beetles caught in cotton (46% in 2008; 56% in 2009) and alfalfa (46% in 2008; 71% in 2009) contained a protein mark, thus indicating that convergent lady beetle movement was largely bidirectional between the adjacent crops. Although at a much lower proportion, lady beetles also showed unidirectional movement from cotton to alfalfa (5% in 2008 and 6% in 2009) and from alfalfa to cotton (9% in 2008 and 14% in 2009). The season-long bidirectional movement exhibited by the beetles was significantly higher in alfalfa than cotton during both years of the study. The total influx of lady beetles (bidirectional and unidirectional combined) was significantly higher in alfalfa compared with that in cotton for both years. While convergent lady beetles moved between adjacent cotton and alfalfa, they were more attracted to alfalfa when cotton was not flowering and/or when alfalfa offered more opportunities for prey. This study offers much needed information on intercrop movement of the convergent lady beetle that should facilitate integrated pest management decisions in cotton utilizing conservation biological control.

Seeds of change: corn seed mixtures for resistance management and integrated pest management.

The use of mixtures of transgenic insecticidal seed and nontransgenic seed to provide an in-field refuge for susceptible insects in insect-resistance-management (IRM) plans has been considered for at least two decades. However, the U.S. Environmental Protection Agency has only recently authorized the practice. This commentary explores issues that regulators, industry, and other stakeholders should consider as the use of biotechnology increases and seed mixtures are implemented as a major tactic for IRM. We discuss how block refuges and seed mixtures in transgenic insecticidal corn, Zea mays L., production will influence integrated pest management (IPM) and the evolution of pest resistance. We conclude that seed mixtures will make pest monitoring more difficult and that seed mixtures may make IRM riskier because of larval behavior and greater adoption of insecticidal corn. Conversely, block refuges present a different suite of risks because of adult pest behavior and the lower compliance with IRM rules expected from farmers. It is likely that secondary pests not targeted by the insecticidal corn as well as natural enemies will respond differently to block refuges and seed mixtures.