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Lygus Hahn (Hemiptera: Miridae) are serious pests of agricultural and greenhouse crops throughout North America. In Europe, bivoltine Peristenus Forster (Hymenoptera: Braconidae) species have a significant impact on Lygus populations. Release and establishment of European P. digoneutis Loan in Lygus lineolaris (Palisot de Beauvois) populations in northeastern USA has renewed interest in the intended liberation of European parasitoids for Lygus control in Canada. Accurate identification of natural enemies is the cornerstone of biological control but conventional methods for identifying Peristenus species and estimating parasitism rates rely on tedious and time-consuming dissection and rearing methods. The present study describes species-specific PCR primers for three species of Peristenus, and the use of a multiplex PCR assay to detect P. digoneutis and P. stygicus Loan eggs and larvae from Lygus rugulipennis Poppius nymphs. Results indicate that the primers amplify uniquely sized, species-specifi...

Species-specific primers for four species of Neofabraea associated with apple and pear fruit diseases were used in multiplex PCR assays to identify 29 putative Neofabraea isolates, primarily isolated from bull's-eye rot on pears from packing houses in Washington and Oregon. Apples were inoculated with these isolates, and tentative identifications based on morphology of conidia forming on wound-inoculated fruits were compared with identifications made using species-specific primers for different Neofabraea species. PCR-based identifications were successful for 26 of 29 isolates, and in all cases were consistent with tentative identifications based on spore morphologies. The results revealed that in addition to the two species of Neofabraea already known to occur in the Pacific Northwest, N. malicorticis and N. perennans, a third species, N. alba, is also prevalent.

Five species of pathogenic fungi belong to Neofabraea. One of these, N. krawtzewii (syn. N. populi ), is responsible for bark lesions on poplar ( Populus ) trees. The other four species cause post-harvest bull's eye rot of pome fruits, and at least two of these also cause bark cankers on pome fruit trees. Morphological variation among these species is slight, and overlap in geographic range sometimes occurs. As a consequence, identification based on conventional criteria can be tenuous. PCR primers with putative species specificity were developed following genetic analysis of the β-tubulin gene for isolates of each of the five species of Neofabraea. PCR conditions required to achieve specificity of the primer sets were determined, and a multiplex PCR protocol was developed to optimize their diagnostic utility on apple fruits. A protocol with higher annealing temperatures in the initial PCR cycles followed by lower temperatures in later cycles gave complete species-specificity when the primer sets were used individually and in multiplex, resulting in successful detection of the pathogens from axenic culture and infected apple fruits.

Evaluation of host-parasitoid associations can be tenuous using conventional methods. Molecular techniques are well placed to identify trophic links and resolve host-parasitoid associations. Establishment of the highly invasive brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae), outside Asia has prompted interest in the use of egg parasitoids (Hymenoptera: Scelionidae) as biological control agents. However, little is known regarding their host ranges. To address this, a DNA barcoding approach was taken wherein general PCR primers for Scelionidae and Pentatomidae were developed to amplify and sequence >500-bp products within the DNA barcoding region of the cytochrome oxidase I (COI) gene that would permit the identification of key players in this association. Amplification of DNA from Pentatomidae and Scelionidae was consistent across a broad range of taxa within these families, and permitted the detection of Scelionidae eggs within H. halys 1 h following oviposition. In laboratory assays, amplification and sequencing of DNA from empty, parasitized eggs was successful for both host (100% success) and parasitoid (50% success). When applied to field-collected, empty egg masses, the primers permitted host identification in 50-100% of the eggs analysed, and yielded species-level identifications. Parasitoid identification success ranged from 33 to 67% among field-collected eggs, with genus-level identification for most specimens. The inability to obtain species-level identities for these individuals is due to the lack of coverage of this taxonomic group in public DNA sequence databases; this situation is likely to improve as more species are sequenced and recorded in these databases. These primers were able to detect and identify both pentatomid host and scelionid parasitoid in a hyperparasitized egg mass, thereby clarifying trophic links otherwise unresolved by conventional methodology.

Collections of parasitoids attacking the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), in South Korea yielded specimens that were originally identified as Binodoxys communis (Gahan) (Hymenoptera: Braconidae). We report here on laboratory studies indicating that this population is actually a previously unknown species of Binodoxys. Four classes of comparisons were made between the Korean population and a Chinese population that also had been identified as B. communis. The comparisons included 1) mating trials coupled with behavioral observations and spermathecal examinations, 2) assessment of nucleotide divergence at two mitochondrial and two nuclear gene loci, 3) patterns of host use, and 4) reassessment of morphological characters. These studies revealed premating reproductive isolation of the two populations and minor nucleotide differences in mitochondrial cytochrome oxidase I sequences and nuclear internal transcriber spacer 1 sequences, providing strong indications that they are different species. Subtle morphological differences also were discovered that confirmed that the Chinese population corresponds to B. communis, whereas the Korean population does not. We propose the name Binodoxys koreanus StarÝ, sp. n. for the Korean population. The two species exhibited similar host ranges in the laboratory, the most notable exception being that B. koreanus, sp. n. is better able to develop in a population of Aphis craccivora Koch that harbors the bacterial endosymbiont Hamiltonella defensa Moran, which seems to strongly interfere with the development of B. communis. We discuss the implications of our results for biological control introductions against the soybean aphid in North America.

Brown marmorated stink bug, Halyomorpha halys Stål, is an invasive, herbivorous insect species that was accidentally introduced to the United States from Asia. First discovered in Allentown, PA, in 1996, H. halys has now been reported from at least 40 states in the United States. Additional invasions have been detected in Canada, Switzerland, France, Germany, Italy, and Lichtenstein, suggesting this invasive species could emerge as a cosmopolitan pest species. In its native range, H. halys is classified as an outbreak pest; however, in North America, H. halys has become a major agricultural pest across a wide range of commodities. H. halys is a generalist herbivore, capable of consuming >100 different species of host plants, often resulting in substantial economic damage; its feeding damage resulted in US$37 million of losses in apple in 2010, but this stink bug species also attacks other fruit, vegetable, field crop, and ornamental plant species. H. halys has disrupted integrated pest management programs for multiple cropping systems. Pesticide applications, including broad-spectrum insecticides, have increased in response to H. halys infestations, potentially negatively influencing populations of beneficial arthropods and increasing secondary pest outbreaks. H. halys is also challenging because it affects homeowners as a nuisance pest; the bug tends to overwinter in homes and outbuildings. Although more research is required to better understand the ecology and biology of H. halys,we present its life history, host plant damage, and the management options available for this invasive pest species. Published version