Combining Tpi and CO1 Genetic Markers to Discriminate Invasive Helicoverpa armigera From Local Helicoverpa zea (Lepidoptera: Noctuidae) Populations in the Southeastern United States.

The recent establishment of the Old World pest Helicoverpa armigera (Hübner) into South America has had significant economic consequences and places the rest of the hemisphere at risk, emphasizing the need for improved methods of monitoring. A major complication is that a sibling species endemic to the New World, Helicoverpa zea (Boddie), is morphologically very similar, with the two species capable of producing fertile hybrids in the laboratory. The consequences of such hybridization in the field are uncertain, but could result in significant and unpredictable changes in the timing, range, and pesticide susceptibilities of Helicoverpa infestations. The objective here is to provide new genetic resources applicable to Helicoverpa populations in northern Florida and neighboring states (a region at risk for H. armigera) that can distinguish the two species and possible hybrids. The genetic variability in segments of the mitochondrial cytochrome oxidase 1 (CO1) and the Z-linked triosephosphate isomerase (Tpi) genes were determined for H. zea from the southeastern United States. These were compared to DNA sequences from H. armigera specimens from Morocco, Australia, and Europe. Phylogenetic network analysis showed a clear demarcation between the two species for all gene segments. These results extend earlier studies establishing CO1 as marker for discriminating the Helicoverpa species complex and introduce a new sex-linked genomic marker. The CO1 and Tpi markers in combination provide a more accurate and sensitive method than existing techniques for identifying hybridization between H. zea and H. armigera and could potentially be used to extrapolate the likely source of invasive H. armigera populations.

Efficiency of Trapping Systems for Detecting Tuta absoluta (Lepidoptera: Gelechiidae).

Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), a pest of tomato, was recently detected in Panama in Central America and now threatens to expand into the important tomato production areas of Mexico and the United States. Moths caught in T. absoluta pheromone-baited traps must be removed and dissected to confirm the species present before containment and mitigation strategies are put in place. Timely processing of traps can be hindered by the presence of numerous similar nontarget moths that cannot be easily prescreened. Trapping systems using dry bucket traps or Delta traps with either hot melt pressure sensitive adhesives (HMPSA) or cool melt adhesives were evaluated for their effectiveness in trapping T. absoluta and for their ease in allowing identification of nontarget moths. Delta traps in Panama with HMPSA and cool melt adhesives both trapped T. absoluta with equal efficacy. In Florida, nontarget moths were easier to prescreen from bucket traps and HMPSA inserts. Importantly, moths found in bucket traps as well as on cool melt adhesive inserts were of a lower quality than those on HMPSA inserts, making identification more difficult. Studies conducted in Florida and Panama tomato and potato fields showed that commercially produced pheromones containing only the main pheromone component ((3E, 8Z, 11Z)-tetradecatrien-1-yl acetate) or containing both the main and minor pheromone component ((3E, 8Z)-tetradecadien-1-yl) attracted nontarget moths. Survey programs, particularly large-scale ones, should consider the application of alternative trapping systems or new adhesives available in order to facilitate the visual prescreening of nontarget moths.

Use of DNA barcodes to identify invasive armyworm Spodoptera species in Florida.

A critical component for sustaining adequate food production is the protection of local agriculture from invasive pest insects. Essential to this goal is the ability to accurately distinguish foreign from closely related domestic species, a process that has traditionally required identification using diagnostic morphological "keys" that can be both subtle and labor-intensive. This is the case for the Lepidopteran group of insects represented by Spodoptera, a genus of Noctuidae "armyworm" moths that includes several important agricultural pests. Two of the most destructive species, Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) and S. litura (F.) are not yet established in North America. To facilitate the monitoring for these pests, the feasibility of using DNA barcoding methodology for distinguishing between domestic and foreign Spodoptera species was tested. A DNA barcoding database was derived for a subset of Spodoptera species native to Florida, with an emphasis on those attracted to pheromone blends developed for S. litura or S. littoralis. These were then compared to the barcode sequences of S. litura collected from Taiwan and S. littoralis from Portugal. Consistent discrimination of the different species was obtained with phenetic relationships produced that were generally in agreement with phylogenetic studies using morphological characteristics. The data presented here indicate that DNA barcoding has the potential to be an efficient and accurate supplement to morphological methods for the identification of invasive Spodoptera pests in North America.