Matthew L. Lewis

Two nuclear genes confirm mitochondrial evidence of cryptic species within Liriomyza huidobrensis (Diptera: Agromyzidae).

Abstract Phylogenetic analysis using DNA sequence data from two nuclear genes was undertaken to investigate phylogeographic structure within the widespread leafmining pest Liriomyza huidobrensis (Blanchard). Parsimony analysis of 171 bp from β-tubulin (including an intron) and 921 bp from elongation factor-1α confirms previous findings from mitochondrial sequence data of deep phylogeographic structure indicative of cryptic species within L. huidobrensis. We resurrect the name L. langei Frick for the North American cryptic species and restrict the name L. huidobrensis to the South and Central American cryptic species. Results from nuclear genes also confirm previous results suggesting that recent invasions of this leafminer in many areas of the world are due to the spread of L. huidobrensis from South or Central America.

Hidden Neotropical Diversity: Greater Than the Sum of Its Parts

The diversity of tropical herbivorous insects has been explained as a direct function of plant species diversity. Testing that explanation, we reared 2857 flies from flowers and seeds of 24 species of plants from 34 neotropical sites. Samples yielded 52 morphologically similar species of flies and documented highly conserved patterns of specificity to host taxa and host parts. Widespread species of plants can support 13 species of flies. Within single populations of plants, we typically found one or more fly species specific to female flowers and multiple specialists on male flowers. We suggest that neotropical herbivorous insect diversity is not simply a function of plant taxonomic and architectural diversity, but also reflects the geographic distribution of hosts and the age and area of the neotropics.

Phylogenetic Relationships, Species Limits, and Host Specificity of Gall-Forming Fergusonina Flies (Diptera: Fergusoninidae) Feeding on Melaleuca (Myrtaceae)

Abstract Phylogenetic analysis of recently described gall-forming Fergusonina Malloch flies was performed using DNA sequence data from the mitochondrial cytochrome oxidase I gene. Fifty-three flies reared from nine species of Melaleuca L. were sequenced. Species boundaries delimited by mitochondrial data confirm recent morphological investigation with one exception. Fergusonina turneri Taylor, believed to feed on both Melaleuca quinquenervia (Cav.) S. T. Blake and Melaleuca fluviatilis Barlow, seems to be comprised of two cryptic species, each specialized on one of the two hosts. Because F. turneri is under consideration as a potential biological control agent for invasive M. quinquenervia in the Florida Everglades, understanding cryptic variation and the degree of dietary specialization of this species is critical.

Mitochondrial Phylogeography of Vegetable Pest Liriomyza sativae (Diptera: Agromyzidae): Divergent Clades and Invasive Populations

Abstract The leafmining fly Liriomyza sativae Blanchard is an important polyphagous pest of vegetables crops in the United States and around the world. Phylogeographic analysis of mitochondrial cytochrome oxidase I sequence variation indicates that L. sativae harbors distinct mitochondrial clades suggestive of the presence of cryptic species. Two of the major mitochondrial clades exhibited polyphagy, with members feeding on hosts in at least three plant families. Only one of the major clades was present in introduced populations, causing total mitochondrial variation exhibited by introduced populations to be considerably reduced compared with that observed within the native range.

Lethal Interactions Between Parasites and Prey Increase Niche Diversity in a Tropical Community

Hidden Diversity Why are there so many species in the tropics? Niche partitioning by highly specialized plant species seems to be the main generator of high diversity. Condon et al. (p. 1240; see the Perspective by Godfray) show that niche partitioning can also be generated by interactions between plant resources and parasites, resulting in hyperdiverse communities. The cryptic diversity of 14 neotropical fly pollinators and 18 of their highly specific wasp parasites induced mortality partitions between multiple narrow niches. The extreme specificity of the wasp-fly relationships was initially only revealed by molecular analysis. Incorrect fly-host choice in parasitoid wasps creates multidimensional niches, generating high levels of hidden diversity. Ecological specialization should minimize niche overlap, yet herbivorous neotropical flies (Blepharoneura) and their lethal parasitic wasps (parasitoids) exhibit both extreme specialization and apparent niche overlap in host plants. From just two plant species at one site in Peru, we collected 3636 flowers yielding 1478 fly pupae representing 14 Blepharoneura fly species, 18 parasitoid species (14 Bellopius species), and parasitoid-host associations, all discovered through analysis of molecular data. Multiple sympatric species specialize on the same sex flowers of the same fly host-plant species—which suggests extreme niche overlap; however, niche partitioning was exposed by interactions between wasps and flies. Most Bellopius species emerged as adults from only one fly species, yet evidence from pupae (preadult emergence samples) show that most Bellopius also attacked additional fly species but never emerged as adults from those flies.

Mitochondrial Phylogeography of the Vegetable Pest Liriomyza trifolii (Diptera: Agromyzidae): Diverged Clades and Invasive Populations

Abstract The leafmining fly Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) is an important pest of vegetable and cut-flower crops. In recent decades, this species has become invasive, spreading from the Americas to the rest of the world. Despite substantial losses caused by Liriomyza leafminers, the systematics of these flies has remained poorly understood because of their small size and morphological homogeneity. Previous molecular research on other polyphagous Liriomyza pests has suggested that cryptic species may be present. Here, we use mitochondrial cytochrome oxidase I sequence variation to investigate phylogeographic structure within L. trifolii. Our results indicate that L. trifolii harbors distinct phylogenetic clades, suggesting the presence of cryptic species. There is also evidence of a recently derived, highly specialized pepper (Capsicum spp., Solanaceae)-feeding population within L. trifolii that may represent a host race or even a distinct species. Introduced populations from various locations contained a highly restricted subset of the mitochondrial variation present within L. trifolii, suggesting one or more bottlenecks during colonization.

Geographic Population Structure of the Sugarcane Borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), in the Southern United States

The sugarcane borer moth, Diatraea saccharalis, is widespread throughout the Western Hemisphere, and is considered an introduced species in the southern United States. Although this moth has a wide distribution and is a pest of many crop plants including sugarcane, corn, sorghum and rice, it is considered one species. The objective was to investigate whether more than one introduction of D. saccharalis had occurred in the southern United States and whether any cryptic species were present. We field collected D. saccharalis in Texas, Louisiana and Florida in the southern United States. Two molecular markers, AFLPs and mitochondrial COI, were used to examine genetic variation among these regional populations and to compare the sequences with those available in GenBank and BOLD. We found geographic population structure in the southern United States which suggests two introductions and the presence of a previously unknown cryptic species. Management of D. saccharalis would likely benefit from further investigation of population genetics throughout the range of this species.

A New Cryptic Species of Diatraea (Lepidoptera: Crambidae: Crambinae) Feeding on Eastern Gama Grass and a Novel Host Association with a Braconid (Hymenoptera) in the United States

ABSTRACT A new species, Diatraea mitteri Solis, that had been residing cryptically as Diatraea crambidoides (Grote), feeding on eastern gama grass (Tripsacum dactyloides (L.) L., is described. D. crambidoides occurs in the southern United States and Mexico and is an economic pest of corn (Zea mays L.). It has been reported to also feed on sorghum (Sorghum bicolor (L.) Moench), johnsongrass (Sorghum halepense (L.) Persoon), and sugar cane (Saccharum officinarum L.). We confirm that D. crambidoides also feeds on eastern gama grass. Morphological and molecular characters support the status of D. mitteri as a new species. Parsimony analysis resulted in two clades corresponding to D. crambidoides and D. mitteri. We confirm the distribution of D. mitteri from Kansas, Oklahoma, and Texas, but its distribution could be as broad as the remaining range of eastern gama grass in the eastern United States. All the life stages are described and illustrated. A novel host association, Alabagrus imitatus Cresson (Hymenoptera: Braconidae), as a parasitoid of D. mitteri is reported.

Molecular Survey for the Invasive Leafminer Pest Liriomyza huidobrensis (Diptera: Agromyzidae) in California Uncovers Only the Native Pest Liriomyza langei

ABSTRACT Liriomyza huidobrensis (Blanchard) is a highly destructive invasive leafminer pest currently causing extensive damage to vegetable and horticultural crops around the world. Liriomyza langei Frick is a leafminer pest native to California that cannot currently be morphologically distinguished from L. huidobrensis. We used a DNA-barcoding approach, a published PCR-RFLP method, and a new multiplex PCR method to analyze 664 flies matching the morphological description of huidobrensis—langei. We found no evidence for the presence of L. huidobrensis in our extensive samples from California. In addition to the new molecular method, this work is important because it provides definitive data that the California “pea leafminer” is currently, and has probably always been, L. langei. These data will also be important in the event that the highly invasive L. huidobrensis ever becomes established.

Molecular and Morphological Tools to Distinguish Scyphophorus acupunctatus Gyllenhal, 1838 (Curculionidae: Dryophthorinae): A New Weevil Pest of the Endangered Century Plant, Agave eggersiana from St. Croix, U.S. Virgin Islands

Abstract. The agave snout weevil (AGW) or sisal weevil, Scyphophorus acupunctatus Gyllenhal is here reported for the first time in St. Croix, U.S. Virgin Islands (USVI) where it threatens Agave eggersiana Trel., a USVI endemic and endangered century-plant. We provide molecular, morphological, and behavioral characters to successfully distinguish the two known Scyphophorus species at all developmental stages. We identified seven new larval characters on the mandibles and characters relating to the chaetotaxy of the labrum and labio-maxillary complex as well as new, putatively informative characters for weevil systematics: chitinized arm of mentum (postlabial strut or postlabial bracon) and the presence of 4 ventral malar setae, instead of 5. In the pupae, the difference in number and placement of rostral setae were also found to be diagnostic. We analyzed two genes, mtCO1 and EF1a, to confirm the identity of the immatures. Phylogenetic analysis of both genes separately and together suggests a clear pattern of substantial phylogeographic structure with specimens clustering by geographic location and this pattern strongly suggests the presence of cryptic species or allopatrically diverged populations. We provide management recommendations for the protection of Agave eggersiana against the threat posed by ASW.We also report, for the first time, the presence of Sphenophorus cubensis (Buchanan) in St. Croix and Scyphophorus yuccae Horn in Panama on Hesperoyucca whipplei (Torr.) Trel. (Asparagaceae: Agavoideae).