Photosynthetic characteristics of leaves and fruits of Hickory (<Emphasis Type="Italic">Carya cathayensis</Emphasis> Sarg.) and Pecan (<Emphasis Type="Italic">Carya illinoensis</Emphasis> K.Koch) during fruit development stages

Key message

Fruit photosynthesis in both hickory and pecan significantly contribute to the carbon requirements of late growth stage (corresponding to seed development).

Abstract

Plant parts other than leaves can perform photosynthesis and contribute to carbon acquisition for fruit development. To determine the role of fruit photosynthesis in fruit carbon acquisition in hickory (Carya cathayensis Sarg.) and pecan (Carya illinoensis K.Koch), we studied changes in dry mass, surface area and CO₂ exchange rate in these fruits during fruit development. Fruit development was divided into two phases: phase one involves the rapid increase of fruit size (from 0 to 59 days after pollination (DAP) for hickory; from 0 to 88 DAP for pecan); phase two involves seed development (from 59 to 121 DAP for hickory; from 88 to 155 DAP for pecan). The net photosynthetic rate (P _n) in hickory leaves decreased by 48.5 % from 76 to 88 DAP, while the P _n in pecan leaves decreased by 32.3 % from 88 to 123 DAP. The gross photosynthetic rate (P _g) in hickory fruit was significantly greater than that of the leaf during the late stage (88 to 121 DAP) of fruit development. Pecan fruit had a significantly higher P _g than leaves during ontogeny. The contribution of fruit photosynthesis to fruit carbon requirements increased during fruit development, which was estimated by the gross fruit photosynthesis divided by respiration and increased dry mass. The contribution of fruit photosynthesis to pecan carbon requirements was significantly greater than that of hickory. Fruit photosynthesis in both hickory and pecan significantly contribute to the carbon requirements of late growth stage.

     

Meloidogyne partityla on Pecan Isozyme Phenotypes and Other Host

Meloidogyne sp. from five pecan (Carya illinoensis) orchards in Texas were distinctive in host range and iszoyme profiles from common species of Meloidogyne but were morphologically congruent with Meloidogyne partityla Kleynhans, a species previously known only in South Africa. In addition to pecan, species of walnut (Juglans hindsii and J. regia) and hickory (C. ovata) also were hosts. No reproduction was observed on 15 other plant species from nine families, including several common hosts of other Meloidogyne spp. Three esterase phenotypes and two malate dehydrogenase phenotypes of M. partityla were identified by polyacrylamide gel electrophoresis. Each of these isozyme phenotypes was distinct from those of the more common species M. arenaria, M. hapla, M. incognita, and M. javanica.     

Host‐associated differentiation in a pecan and water hickory Aphidomorpha community

Host‐associated differentiation (HAD) is the formation of genetically distinct, host‐associated populations created and maintained by ecologically mediated reproductive isolation. HAD potentially accounts for species origins in parasites, including herbivorous insects. Although case studies testing the occurrence of HAD are accumulating, it is still unclear how common HAD is and which specific ecological traits explain its occurrence. To address these issues, studies are needed that include negative results (i.e., instances in which parasite populations do not exhibit HAD) and test for HAD across communities (i.e., several parasite species on the same set of host species). In this study, HAD was tested in a community of six species of Aphidomorpha (Hemiptera) that share a host‐plant pair: pecan [Carya illinoinensis (Wangenh.) K.Koch] and water hickory [Carya aquatica (F.Michx) Nutt., both Juglandaceae] trees. All six species are parthenogenetic and three species are endophagous, traits that can exacerbate host‐specific selection. AFLP markers were employed to detect the presence of genetically distinct, host‐associated populations for each insect species. Strict HAD (i.e., the occurrence of genetically distinct pecan‐associated and water hickory‐associated genotypes) was found in Phylloxera notabilis Pergande (Phylloxeridae), Phylloxera devastatrix Pergande, and Monelliopsis pecanis Bissel (Aphididae). Monellia caryella Fitch (Aphididae) displayed a pattern of partial HAD (i.e., the occurrence of only a genetically distinct pecan‐associated genotype). No HAD was found in Melanocallis caryaefoliae Davis (Aphididae) or Phylloxera texana Stoetzel. The pattern of HAD occurrence in the pecan and water hickory Aphidomorpha community indicated that neither parthenogenesis nor endophagy sufficiently explain the occurrence of HAD in this system.     

A novel set of 223 EST-SSR markers in <Emphasis Type="Italic">Casuarina</Emphasis> L. ex Adans.: polymorphisms,cross-species transferability,and utility for commercial clone genotyping

Simple sequence repeat (SSR) markers are very useful for genetic applications in plants, but SSR resource for the important tree genus Casuarina L. ex Adans. is still limited. In this study, we report a novel set of 223 SSR markers in Casuarina developed from expressed sequence tag (EST) resource of GenBank. The 223 EST-SSR markers were polymorphic among 10 unrelated individuals of C. equisetifolia L. Johnson, with the number of alleles per locus (N_a), observed heterozygosity (H_o), expected heterozygosity (H_e), and polymorphic information content (PIC) averaging at 5.5, 0.72, 0.86, and 0.63, respectively. The rates of cross-species transferability ranged from 96.9% (C. glauca Sieber ex Sprengel) through 97.8% (C. cunninghamiana Miquel) to 99.1% (C. junghuhniana Miquel). Fifty-five C. equisetifolia clones widely planted in China were successfully genotyped with a subset of 20 EST-SSRs. These newly developed markers will have a great potential for genetic and breeding applications in Casuarina species and related taxa.     

Development and polymorphism of Vigna unguiculata ssp. unguiculata microsatellite markers used for phylogenetic analysis in asparagus bean (Vigna unguiculata ssp. sesquipedialis (L.) Verdc.)

Asparagus bean (V. unguiculata ssp. sesquipedialis), a specific form of cowpea (V. unguiculata L. Walp.), is cultivated as a vegetable crop throughout eastern and southern Asia for its tender long pods. Little is known about the genetic relationship between asparagus bean and the broader species, particularly the dominant ssp. unguiculata. We report here the development and transferability of simple sequence repeat (SSR) markers, over 40% of which are EST-derived, from ssp. unguiculata to asparagus bean and the use of a subset of the polymorphic markers to assess the genetic diversity of asparagus bean cultivars from diverse geographic origins across China. A total of 410 EST derived SSR (eSSR) markers and 600 SSR markers derived from cowpea genespace sequences (GSS) were developed, with a cross-subspecies transferability of 100% and 98.5%, respectively. In a recombinant inbred line population of asparagus bean, a 1:1 segregation was observed for most loci. Principal coordinate analysis (PCA) and phylogenetic clustering based on 62 alleles detected by 14 polymorphic SSR markers distinguished ssp. unguiculata and sesquipedialis into separate groups. Improved asparagus bean cultivars in China generally have a narrow genetic basis compared with landraces varieties. This suggests that asparagus bean breeding programs need to consider utilizing landrace germplasm to enhance genetic variability and ensure long-term gains from selection and reduce genetic vulnerability to pathogen/pest epidemics. Because of their transferability across subspecies, the SSR markers described in this study could be effectively employed in cross-subspecies trait introgression breeding from ssp. unguiculata to sesquipedialis.     

Transferability and polymorphism of barley EST-SSR markers used for phylogenetic analysis in Hordeum chilense

Background

Hordeum chilense, a native South American diploid wild barley, is a potential source of useful genes for cereal breeding. The use of this wild species to increase genetic variation in cereals will be greatly facilitated by marker-assisted selection. Different economically feasible approaches have been undertaken for this wild species with limited direct agricultural use in a search for suitable and cost-effective markers. The availability of Expressed Sequence Tags (EST) derived microsatellites or simple sequence repeat (SSR) markers, commonly called as EST-SSRs, for barley (Hordeum vulgare) represents a promising source to increase the number of genetic markers available for the H. chilense genome.

Results

All of the 82 barley EST-derived SSR primer pairs tested for transferability to H. chilense amplified products of correct size from this species. Of these 82 barley EST-SSRs, 21 (26%) showed polymorphism among H. chilense lines. Identified polymorphic markers were used to test the transferability and polymorphism in other Poaceae family species with the aim of establishing H. chilense phylogenetic relationships. Triticum aestivum-H. chilense addition lines allowed us to determine the chromosomal localizations of EST-SSR markers and confirm conservation of the linkage group.

Conclusion

From the present study a set of 21 polymorphic EST-SSR markers have been identified to be useful for diversity analysis of H. chilense, related wild barleys like H. murinum, and for wheat marker-assisted introgression breeding. Across-genera transferability of the barley EST-SSR markers has allowed phylogenetic inference within the Triticeae complex.     

Ectomycorrhizal fungal diversity in orchards of cultivated pecan (Carya illinoinensis; Juglandaceae)

Carya illinoinensis (pecan) belongs to the Juglandaceae (walnut family) and is a major economic nut crop in the southern USA. Although evidence suggests that some species in the Juglandaceae are ectomycorrhizal, investigations on their ectomycorrhizal fungal symbionts are quite limited. Here we assessed the ectomycorrhizal fungal diversity in cultivated orchards of C. illinoinensis. Five pecan orchards in southern Georgia, USA, were studied, three of which were known to fruit the native edible truffle species Tuber lyonii. We sequenced rDNA from single ectomycorrhizal root tips sampled from a total of 50 individual trees. Mycorrhizae were identified by ITS and LSU rDNA sequence-based methods. Forty-four distinct ectomycorrhizal taxa were detected. Sequestrate taxa including Tuber and Scleroderma were particularly abundant. The two most abundant sequence types belonged to T. lyonii (17%) and an undescribed Tuber species (~20%). Because of our interest in the ecology of T. lyonii, we also conducted greenhouse studies to determine whether this species would colonize and form ectomycorrhizae on roots of pecan, oak, or pine species endemic to the region. T. lyonii ectomycorrhizae were formed on pecan and oak seedlings, but not pine, when these were inoculated with spores. That oak and pecan seedling roots were receptive to truffle spores indicates that spore slurry inoculation could be a suitable method for commercial use and that, ecologically, T. lyonii may function as a pioneer ectomycorrhizal species for these hosts.     

The gut bacteria symbionts from the monophagous insect Acrobasis nuxvorella produce tannase for the digestion of Carya illinoinensis tannins

Acrobasis nuxvorella Neuzing (Lepidoptera: Pyralidae), or the Pecan Nut Casebearer (PNC), is a monophagous pecan nut [Carya illinoinensis (Wang) K. Koch] herbivore. This insect has caused major crop losses, despite pecan nut trees producing a high concentration of tannins, which are deterrent compounds for insects. The PNC consumes and processes tannin-rich tissues without any negative effects on its nutrition. Certain bacterial species of the herbivore gut microbiota have been proven to produce tannase, therefore, we hypothesize that the PNC has symbiotic bacteria that produce tannase for the digestion of tannin contained in their food.In this work, live PNC larvae were extracted from pecan nutlets. The larval guts were dissected and their contents were cultured to obtain the cultivable bacteria. A total of 224 bacterial isolates were recovered, 19 of which tested positive for tannase activity. Isolates LB66, LB24, TT29, and TP8 displayed comparable activity to the control strain Pseudomonas aeruginosa. Further enzyme semi-purification steps showed specific tannase activity values in the range of 39.5–3.7 U/mg of protein. The isolates were identified as Bacillus pumilus strain TT29, Bacillus pumilus strain LB66, Bacillus pumilus strain LB24 and Sthaphylococcus warneri (TP8) by 16S ribosomal RNA gene sequencing. Our findings indicate that PNC larvae contain gut bacteria able to produce tannase that hydrolyze the galloyl ester bonds in tannins.     

Differences in bacterial diversity of host-associated populations of Phylloxera notabilis Pergande (Hemiptera: Phylloxeridae) in pecan and water hickory

Host‐associated differentiation (HAD) is the presence of genetically divergent, host‐associated populations. It has been suggested that microbial symbionts of insect herbivores may play a role in HAD by allowing their insect hosts to use different plant species. The objective of this study was to document if host‐associated populations of Phylloxera notabilis Pergande (Hemiptera: Phylloxeridae) in pecan and water hickory corresponded with differences in the composition of their associated bacteria. To test this hypothesis, we characterized the symbionts present in P. notabilis associated with these two tree species through metagenomic analyses using 454 sequencing. Differences in bacterial diversity were found between P. notabilis populations associated with pecan and water hickory. The bacteria, Pantoea agglomerans and Serratia marcescens, were absent in the P. notabilis water hickory population, whereas both species accounted for more than 69.72% of bacterial abundance in the pecan population.     

Girdling by notodontid caterpillars: distribution and occurrence

Girdling insects produce a circular groove around a stem or petiole typically before ovipositing or feeding on the distal section. We documented that seven of the 11 species of notodontid caterpillars that we studied, including members of five genera in two subfamilies, chewed girdles in seven families of trees including species of birch, hickory, oak, elm, cherry, willow, and maple. The frequency of girdling varied with notodontid species, tree species, month, and year. Free-ranging final instar larvae of Schizura leptinoides on pecan (Carya illinoensis) spent 4?C11?% of their time cutting and reinspecting girdles over 5-h and 12-h observation periods. Feeding occurred proximal as well as distal to girdles, a result not expected by most hypotheses for the function of girdling. Histological examination of S. leptinoides girdles on river birch (Betula nigra) revealed that only the xylem remained intact; however, on pecan, both the xylem and phloem remained mostly uncut by the girdle. S. leptinoides larvae often rubbed their mouthparts over the surface of finished girdles, anointing them with fluid from the labial salivary glands or possibly the ventral eversible gland. After feeding, S. leptinoides and other notodontids sometimes severed the petiole even when the leaf was only partially eaten; these leaf-clipping larvae were similarly observed rubbing their mouthparts over the severed petiole stub. We propose that notodontids cut girdles and clip leaves at least in part to introduce secretions or their enzymatic products into the vascular system to suppress host defenses and/or enhance nutrition.     

Development and characterization of microsatellite markers for genomic analysis of yarrow (Achillea millefolium L.)

Yarrow (Achillea millefoilum L.) is an important medicinal plant with different medicinal and ornamental uses. In this study, SSR markers were developed for the first time from the genome A. millefolium using the slightly modified Hamilton protocol. Three yarrow genomic libraries were constructed, enriched for microsatellite motifs AG, AC and ATG. A total of 30 primer pairs were developed of which 16 were polymorphic in 26 A. millefolium accessions. One accession from A. tenuifolia species was also included to assess the transferability of new developed SSR primers in other species. The average allele number of SSR markers was 8.5 per locus and ranged from 2 to 14. The observed heterozygosity (H _O) varied from 0 to 0.96 with an average of 0.52 and the expected heterozygosity (H _E) ranged from 0.07 to 0.49 with an average of 0.39. Among primers, Am142 showed the highest polymorphic information content (PIC) and the lowest value was obtained from Am59 primer with an average of 0.33. Three loci (AmK59, AmK344 and AmK329) deviated significantly from Hardy-Wrinberg Equlibrium (HWE) and one locus (Am344) might have null alleles. Cluster and PCoA analyses classified A. millefolium accessions according to their geographical distribution and A. tenuifolia species completely separated from A. millefoliulm genotypes.     

Development of genomic simple sequence repeat markers in opium poppy by next-generation sequencing

Opium poppy (Papaver somniferum L.) is an important pharmaceutical crop with very few genetic marker resources. To expand these resources, we sequenced genomic DNA using pyrosequencing technology and examined the DNA sequences for simple sequence repeats (SSRs). A total of 1,244,412 sequence reads were obtained covering 474 Mb. Approximately half of the reads (52 %) were assembled into 166,724 contigs representing 105 Mb of the opium poppy genome. A total of 23,283 non-redundant SSRs were identified in 18,944 contigs (11.3 % of total contigs). Trinucleotide and tetranucleotide repeats were the most abundant SSR repeats, accounting for 49.0 and 27.9 % of all SSRs, respectively. The AAG/TTC repeat was the most abundant trinucleotide repeat, representing 19.7 % of trinucleotide repeats. Other SSR repeat types were AT-rich. A total of 23,126 primer pairs (98.7 % of total SSRs) were designed to amplify SSRs. Fifty-three genomic SSR markers were tested in 37 opium poppy accessions and seven Papaver species for determination of polymorphism and transferability. Intraspecific polymorphism information content (PIC) values of the genomic SSR markers were intermediate, with an average 0.17, while the interspecific average PIC value was slightly higher, 0.19. All markers showed at least 88 % transferability among related species. This study increases sequence coverage of the opium poppy genome by sevenfold and the number of opium poppy-specific SSR markers by sixfold. This is the first report of the development of genomic SSR markers in opium poppy, and the genomic SSR markers developed in this study will be useful in diversity, identification, mapping and breeding studies in opium poppy.     

Transferability of SSR markers among wheat,rye, and triticale

Simple sequence repeat (SSR) markers are a valuable tool for many purposes, such as mapping, fingerprinting, and breeding. However, they are only available in some economically important crops because of the high cost and labor intensity involved in their development. Comparative mapping reveals a high degree of colinearity between closely related species, which allows the exchange of markers between them. Our objective was to examine the transferability of SSR markers among wheat (Triticum aestivum L.), rye (Secale cereale L.), and triticale (X Triticosecale Wittmack). One hundred forty-eight wheat and 28 rye SSR markers were used to amplify genomic DNA extracted from five lines each of wheat, rye, and triticale. Transferability of wheat SSR markers to rye was 17%, whereas 25% of rye markers were amplifiable in wheat. In triticale, 58% and 39% transferability was achieved for wheat and rye markers, respectively. Wheat markers gave an average of 2.6, 2.7, and 2.4 polymorphic bands in wheat, rye, and triticale, respectively, while rye markers gave an average of 2.0 in rye and none in wheat and triticale. These transferable markers can now be exploited for further genetic and breeding studies in these species.Nebraska Agricultural Research Division, Journal Series No. 14243Communicated by B. Friebe     

Host‐associated genetic differentiation in pecan leaf phylloxera

Host‐associated differentiation (HAD) is the formation of genetically distinct host‐associated populations. One of the genotypic signatures of HAD is that populations exhibit stronger differentiation by host‐plant species than by geographic isolation. HAD, as a mechanism promoting ecological speciation, has been invoked to explain phytophagous insect diversity. Two traits proposed to promote HAD are endophagy and parthenogenesis. Using amplified fragment length polymorphisms (AFLPs), we tested for the presence of HAD in pecan leaf phylloxera, Phylloxera notabilis Pergande (Hemiptera: Phylloxeridae), an endophagous, gall inducing, and cyclically parthenogenetic insect on sympatric pecan and water hickory at a geographic mesoscale. This species shows strong HAD. Whereas the effect of collecting site was significant, accounting for 7.3% of molecular variation, host‐plant species identity accounted for 63.5%. In addition, a choice test indicated that pecan leaf phylloxera originating from water hickory showed weak but significant preference for leaflets of the natal host, whereas pecan leaf phylloxera originating from pecan did not. This is the first such study of a species of arboreal Phylloxeridae, a poorly known insect group. This is also the first endophage and the second parthenogen shared by these two hickory species to show evidence of HAD. This hickory system could be a good parthenogen‐rich counterpoint to the goldenrod system in the study of HAD in insect communities.     

Development of simple sequence repeat markers and diversity analysis in alfalfa (Medicago sativa L.)

Efficient and robust molecular markers are essential for molecular breeding in plant. Compared to dominant and bi-allelic markers, multiple alleles of simple sequence repeat (SSR) markers are particularly informative and superior in genetic linkage map and QTL mapping in autotetraploid species like alfalfa. The objective of this study was to enrich SSR markers directly from alfalfa expressed sequence tags (ESTs). A total of 12,371 alfalfa ESTs were retrieved from the National Center for Biotechnology Information. Total 774 SSR-containing ESTs were identified from 716 ESTs. On average, one SSR was found per 7.7 kb of EST sequences. Tri-nucleotide repeats (48.8 %) was the most abundant motif type, followed by di—(26.1 %), tetra—(11.5 %), penta—(9.7 %), and hexanucleotide (3.9 %). One hundred EST–SSR primer pairs were successfully designed and 29 exhibited polymorphism among 28 alfalfa accessions. The allele number per marker ranged from two to 21 with an average of 6.8. The PIC values ranged from 0.195 to 0.896 with an average of 0.608, indicating a high level of polymorphism of the EST–SSR markers. Based on the 29 EST–SSR markers, assessment of genetic diversity was conducted and found that Medicago sativa ssp. sativa was clearly different from the other subspecies. The high transferability of those EST–SSR markers was also found for relative species.     

Phenotypic screening of pecan seedling rootstocks in search of nematode resistance

Key Message

Open-pollinated seedstocks for pecan vary in phenology and composition predictably based on their provenance of origin in ways that impact performance.

Abstract

Open-pollinated rootstocks of pecan (Carya illinoinensis), water hickory (Carya aquatica), and their hybrids (Carya × lecontei) were screened for nematode resistance in outdoor above-ground box-plots. Seedstocks were selected to represent the broad geographic range of species diversity. Seedlings were inoculated with eggs of Meloidogyne partityla, the primary nematode pest of Carya, and were harvested after 1 year. All seedlings, except one, manifested nematode damage at moderate to high levels. Evidence of galling was greatest in seedlings from the southern provenance (Mexico), which rated comparably with seedlings from ‘Elliott’. No sources of resistance to Meloidogyne partityla were observed. The box structure allowed harvest of complete root systems and evaluation of plant composition in greater detail than previously observed. Seedlings from the southern provenance were generally distinguishable from other provenances in timing of seasonal growth, stem diameter and seedling height, which is consistent with previous observations. Root and stem dry weights were greatest in seedlings from the southern provenance, as expected based on size measurements. Percent root water varied significantly as a function of seedstock origin, and was negatively correlated with leaf weight. Leaf weights were positively correlated with dates of growth initiation. Uninfected control plants were not observed in this screening effort, and their absence limits the interpretation of patterns. Implications of these observations, as evidence of regional adaptation, merit further exploration by research.     

Genome-Wide Microsatellite Characterization and Marker Development in the Sequenced Brassica Crop Species

Although much research has been conducted, the pattern of microsatellite distribution has remained ambiguous, and the development/utilization of microsatellite markers has still been limited/inefficient in Brassica, due to the lack of genome sequences. In view of this, we conducted genome-wide microsatellite characterization and marker development in three recently sequenced Brassica crops: Brassica rapa, Brassica oleracea and Brassica napus. The analysed microsatellite characteristics of these Brassica species were highly similar or almost identical, which suggests that the pattern of microsatellite distribution is likely conservative in Brassica. The genomic distribution of microsatellites was highly non-uniform and positively or negatively correlated with genes or transposable elements, respectively. Of the total of 115 869, 185 662 and 356 522 simple sequence repeat (SSR) markers developed with high frequencies (408.2, 343.8 and 356.2 per Mb or one every 2.45, 2.91 and 2.81 kb, respectively), most represented new SSR markers, the majority had determined physical positions, and a large number were genic or putative single-locus SSR markers. We also constructed a comprehensive database for the newly developed SSR markers, which was integrated with public Brassica SSR markers and annotated genome components. The genome-wide SSR markers developed in this study provide a useful tool to extend the annotated genome resources of sequenced Brassica species to genetic study/breeding in different Brassica species.     

Development and characterization of EST-SSR markers from Jatropha curcas EST database and their transferability across jatropha-related species/genus

Jatropha curcas (jatropha) is a multipurpose plant with potential as a raw material for biofuel. In the present study, a total of 43,349 expressed sequence tags (ESTs) from J. curcas were searched for type and frequency of simple sequence repeat (SSR) markers. Five thousand one hundred and seventy-five sequences were indentified to contain 6,108 SSRs with 90.8% simple and 9.2% compound repeat motifs. One hundred and sixty-three EST-SSRs were developed and used to evaluate the transferability and genetic relatedness among 4 accessions of J. curcas from China, Mexico, Thailand and Vietnam; 5 accessions of congeneric species, viz. J. gossypiifolia, dwarf J. integerrima, normal J. integerrima, J. multifida, J. podagrica; and Ricinus communis. The polymorphic markers showed 75.56–85.19% transferability among four species of Jatropha and 26.67% transferability across genera in Ricinus communis. Investigation of genetic relatedness showed that J. curcas and J. integerrima are closely related. EST-SSRs used in this study demonstrate a high efficiency of cross species/genera amplification and are useful for identifying genetic diversity of jatropha and its close taxa and to choose the desired related species for wide crossing to improve new varieties of jatropha. The markers can also be further exploited for genetic resource management and genetic improvement of related species/genera through marker-assisted breeding programs.     

Population structure of the pecan nut casebearer Acrobasis nuxvorella throughout its geographical distribution

• 1 The pecan nut casebearer Acrobasis nuxvorella Neunzig (Lepidoptera: Pyralidae) is an important, monophagous pest of pecan Carya illinoinensis (Fagales: Juglandaceae).
• 2 This pest is native from Louisiana west to the eastern edge of New Mexico and north to Illinois in the U.S.A. and as far west as Chihuahua and south to Oaxaca in Mexico.
• 3 Recently, this pest has expanded beyond the native range of pecan into regions where pecan has been introduced for cultivation.
• 4 Amplified fragment length polymorphism markers were used to determine the population genetic structure of this insect pest across its current geographical distribution.
• 5 Population genetic analyses indicate a great degree of genetic structure in the pecan nut casebearer across its geographical distribution, with genetically distinct populations occurring in those areas where the pecan nut casebearer is not native but has been invasive.