Application of molecular techniques to identification of three plusiine species, Autographa nigrisigna, Macdunnoughia confusa, and Thysanoplusia intermixta (Lepidoptera: Noctuidae), found in integrated pest management lettuce fields in Japan

Perception of Heterospecific Sex Pheromone Causes Less Effective Mating Disruption in the Beet Semilooper, Autographa nigrisigna (Lepidoptera: Noctuidae)

Confuser® V is a pheromone-based mating disruptant designed to reduce damage caused by seven species of moth pests, including the beet semilooper, Autographa nigrisigna (Lepidoptera: Noctuidae). Eggs and larvae of A. nigrisigna are often found in fields treated with Confuser® V, suggesting that some components in the Confuser® V blend may have adverse effects on the efficacy of mating disruption of this species. Therefore, we examined whether A. nigrisigna perceives heterospecific pheromone components in the Confuser® V blend and delineated the roles of these components with respect to attraction and communication disruption. We found that several heterospecific pheromone components in the Confuser® V blend were perceived by male A. nigrisigna, and the addition of these components to the pheromone blend of A. nigrisigna reduced the attraction of males in the field, and tended to reduce the efficacy of mating disruption in cage bioassays.

A ddPCR Assay for Identification of Autographa gamma (Noctuidae: Plusiinae) in Bulk Trap Samples

The silver Y moth [Autographa gamma (Linneaus) (Noctuidae: Plusiinae)] is a pervasive crop pest in its native range but has not been found in moth surveys in the United States. Specimens of A. gamma are often intercepted at U.S. ports of entry, so the risk of introduction of this invasive species is high. Currently, identification of Plusiinae adults captured in domestic surveys is done by morphlogical comparison; however, this method is time consuming and misidentifications have occurred in the past. A recent study outlined a real-time PCR assay capable of rapidly identifying individual A. gamma specimens using CO1. This same study provided preliminary data for a droplet digital PCR (ddPCR) assay capable of processing bulk trap samples. Here, we develop and test a ddPCR assay for detecting a single A. gamma in a trap sample of 200 individual moths. This assay will drastically reduce the time and cost needed to screen domestic trap samples for A. gamma.

A Real-Time PCR Assay for the Separation of Autographa gamma (Noctuidae: Plusiinae) From Morphologically Similar Species in North America

The silver Y moth, Autographa gamma L. (Noctuidae: Plusiinae), is a pest of major economic importance in its native range of Europe, Asia, and North Africa. Although not present in North America, larvae of A. gamma are commonly intercepted in commodity shipments at U.S. ports, and adult surveys are conducted each year in more than 20 states. Because of the similarity of A. gamma to several native North American species that are attracted to the same pheromone lure, morphological identification of adults is difficult and requires dissection. In 2010, a specimen of Autographa californica (Speyer, 1875) (Lepidoptera: Noctuidae) from Pennsylvania was incorrectly identified as A. gamma, signaling the need for an alternative method of rapid identification. Here we detail a real-time PCR assay capable of identifying A. gamma specimens in approximately 45 min using extracted DNA. The assay uses a hydrolysis probe that targets a species-specific segment of the CO1 DNA barcode region, while a control probe targets a conserved region of 18S rDNA. The assay was tested with two independent runs of 452 specimens of Plusiinae representing 23 different species. The assay provided unambiguous data 99.7% of the time and did not result in any false positives; these data were used to develop a rule set for interpreting the real-time PCR results. In addition, the same diagnostic probe was tested in bulk sample simulations using real-time PCR and droplet digital PCR where A. gamma could be detected in concentrations as low as 1:1,000,000 (gamma:californica). These experiments provide baseline data for developing a bulk sample assay.