Conventional Sampling Plan for Scouting Neoleucinodes elegantalis (Lepidoptera: Crambidae) Eggs on Tomato Fruits.

The small tomato borer, Neoleucinodes elegantalis (Guenée), is an important pest of tomato (Solanum lycopersicum L.) in South and Central America. This pest is a potential threat for many tomato-producing areas and was listed in 2014 as an A1 quarantine pest by the European and Mediterranean Plant Protection Organization.

Blended Refuge and Insect Resistance Management for Insecticidal Corn.

In this review, we evaluate the intentional mixing or blending of insecticidal seed with refuge seed for managing resistance by insects to insecticidal corn (Zea mays). We first describe the pest biology and farming practices that will contribute to weighing trade-offs between using block refuges and blended refuges. Case studies are presented to demonstrate how the trade-offs will differ in different systems.

Evolution of Resistance by Helicoverpa zea (Lepidoptera: Noctuidae) Infesting Insecticidal Crops in the Southern United States.

We created a deterministic, frequency-based model of the evolution of resistance by corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), to insecticidal traits expressed in crops planted in the heterogeneous landscapes of the southern United States. The model accounts for four generations of selection by insecticidal traits each year. We used the model results to investigate the influence of three factors on insect resistance management (IRM): 1) how does adding a third insecticidal trait to both corn and cotton affect durability of the products, 2) how does unstructured corn refuge influence IRM, and 3) how do block refuges (50% compliance) and blended refuges compare with regard to IRM? When Bt cotton expresses the same number of insecticidal traits, Bt corn with three insecticidal traits provides longer durability than Bt corn with two pyramided traits.

Survival of Corn Earworm (Lepidoptera: Noctuidae) on Bt Maize and Cross-Pollinated Refuge Ears From Seed Blends.

Refuge is mandated in the United States where genetically modified maize (Zea mays L.) expressing insecticidal proteins derived from Bacillus thuringiensis Berliner (Bt) are cultivated. Currently, refuge is deployed in different ways including blocks, field strips, or seed blends containing Bt and non-Bt maize.

Cross-resistance and mechanism of resistance to Cry1Ab toxin from Bacillus thuringiensis in a field-derived strain of European corn borer, Ostrinia nubilalis.

The cross-resistance spectrum and biochemical mechanism of resistance to the Bacillus thuringiensis Cry1Ab toxin was studied in a field-derived strain of Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) that was further selected in the laboratory for high levels (>1000-fold) of resistance to Cry1Ab. The resistant strain exhibited high levels of cross-resistance to Cry1Ac and Cry1Aa but only low levels of cross-resistance (<4-fold) to Cry1F. In addition, there was no significant difference between the levels of resistance to full-length and trypsin-activated Cry1Ab protein.

Control failure likelihood and spatial dependence of insecticide resistance in the tomato pinworm, Tuta absoluta.

Background: Insecticide resistance is a likely cause of field control failures of Tuta absoluta, but the subject has been little studied. Therefore, resistance to ten insecticides was surveyed in seven representative field populations of this species. The likelihood of control failures was assessed, as well as weather influence and the spatial dependence of insecticide resistance.

Fitness costs of Cry1Ab resistance in a field-derived strain of Ostrinia nubilalis (Lepidoptera: Crambidae).

The study of fitness costs associated with resistance to toxins from Bacillus thuringiensis Berliner (Bt) in Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) is important for understanding resistance evolution and for evaluating resistance management practices that prevent or mitigate resistance to transgenic corn, Zea mays L. Resistant individuals identified from a field collection in Kandiyohi, MN, were used to generate a Cry1Ab-resistant strain. We used susceptible and resistant strains with similar genetic background to establish crosses and estimate dominance of fitness costs by measuring fitness components and population parameters determined by fertility life tables.

Expressed sequence tags from larval gut of the European corn borer (Ostrinia nubilalis): exploring candidate genes potentially involved in Bacillus thuringiensis toxicity and resistance.

Background: Lepidoptera represents more than 160,000 insect species which include some of the most devastating pests of crops, forests, and stored products. However, the genomic information on lepidopteran insects is very limited. Only a few studies have focused on developing expressed sequence tag (EST) libraries from the guts of lepidopteran larvae.

On-plant survival and inheritance of resistance to Cry1Ab toxin from Bacillus thuringiensis in a field-derived strain of European corn borer, Ostrinia nubilalis.

Background: The high dose plus refuge is one of the major components of the resistance management plan mandated for transgenic corn expressing Cry toxins from Bacillus thuringiensis Berliner (Bt) that targets the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae). This strategy was based on assumptions such as functional recessive inheritance, which has not been previously tested for O. nubilalis.

Comparison and validation of methods to quantify Cry1Ab toxin from Bacillus thuringiensis for standardization of insect bioassays.

Standardization of toxin preparations derived from Bacillus thuringiensis (Berliner) used in laboratory bioassays is critical for accurately assessing possible changes in the susceptibility of field populations of target pests. Different methods were evaluated to quantify Cry1Ab, the toxin expressed by 80% of the commercially available transgenic maize that targets the European corn borer, Ostrinia nubilalis (Hübner). We compared three methods of quantification on three different toxin preparations from independent sources: enzyme-linked immunosorbent assay (ELISA), sodium dodecyl sulfate-polyacrylamide gel electrophoresis and densitometry (SDS-PAGE/densitometry), and the Bradford assay for total protein.

Toxicity of insecticides to the sweetpotato whitefly (Hemiptera: Aleyrodidae) and its natural enemies.

Efficient chemical control is achieved when insecticides are active against insect pests and safe to natural enemies. In this study, the toxicity of 17 insecticides to the sweetpotato whitefly, Bemisia tabaci (Gennadius), and the selectivity of seven insecticides to natural enemies of this insect pest were evaluated. To determine the insecticide toxicity, B.