Damage from species of Agromyzidae (Diptera) on their plant host(s) is caused mostly by internal larval feeding, but additional damage can arise from female oviposition and feeding punctures, which results in structural damage, the vectoring of viruses and pathogenic fungi, and the exposure of tissue to secondary infection. Many plants of agricultural and ornamental importance are attacked in the field and in glasshouses, and while fly populations are normally kept in check by hymenopterous parasitoids, they sometimes occur in large enough numbers to affect yield and may destroy entire crops. Species affecting crops may be specialists on one host or a larger number of related hosts, but only 16 species in the genera Liriomyza Mik, Phytomyza Fallén and Tropicomyia Spencer are polyphagous, occurring on many hosts in a wide range of families. The threat of these flies is compounded by increasing insecticide resistance and the ease by which polyphagous species can multiply on weeds around growing areas or on alternate crops. All species are also readily spread through trade on their host plant or in soil, causing some species to become globally invasive, with some being of quarantine concern. Since understanding these pests is integral to their control, the objective of the present study is to provide an overview of agromyzid biology, ecology and agricultural importance. Detailed consideration is additionally provided for 26 major pests of special concern. These include eight species of the subfamily Agromyzinae [Agromyza frontella (Rondani); A. megalopsis Hering; A. parvicornis Loew; Melanagromyza sojae (Zehntner), Ophiomyia phaseoli (Tyron), O. simplex (Loew), O. spencerella (Greathead), and Tropicomyia theae (Cotes)] and 18 species of the subfamily Phytomyzinae [Amauromyza flavifrons (Meigen), Liriomyza brassicae (Riley), L. bryoniae (Kaltenbach), L. chinensis (Kato), L. congesta (Becker), L. huidobrensis (Blanchard), L. langei Frick, L. sativae Blanchard, L. strigata (Meigen), L. trifolii (Burgess), Phytobia cambii (Hendel), Phytomyza gymnostomaLoew, P. horticola Goureau, P. ilicicola Loew, P. ilicis Curtis, P. nigra Meigen, P. rufipes Meigen, and P. syngenesiae (Hardy)]. For each of these species, an overview of contemporary knowledge is provided for identification and diagnosis, global distribution, hosts plant(s), host damage, biology, and means of movement and dispersal. To aid in control, early warning systems, and means of field monitoring and management are provided.

Insects that feed on plants are widely used for studies of host-plant-associated speciation due to their diversity and tractability. The value of these studies necessarily depends upon an accurate understanding of the diet of the focal insects. In North America, the 12 Phytomyza Fallén (Diptera: Agromyzidae) leafmining fly species feeding on hollies (Ilex spp. (Aquifoliaceae: Ilex)) initially appeared to be primarily a host-plant-associated radiation of largely monophagous species. However, our increased collecting efforts found that a majority of the morphospecies are oligophagous, feeding on multiple Ilex species. Patterns of host-associations suggest that colonization of new hosts followed by host-associated speciation may be an important feature of diversification. Analyses of mitochondrial COI data in three oligophagous species found evidence of host-associated genetic structure consistent with processes of host-associated divergence. However, in one of these species, evidence of geographic divergence as well as host-associated divergence was detected, illustrating complexity in factors relating to speciation and host-use evolution in this radiation of leafmining flies.

The agromyzid leafminer Liriomyza trifolii (Burgess) is an important polyphagous pest of vegetable crops and ornamental plants. It is native to the Americas but has spread throughout the world over the past 50 years. Previous molecular research has indicated that this species contains highly distinct mitochondrial lineages suggestive of cryptic species. To better interpret the mitochondrial divergence, we used anchored hybrid enrichment datasets in order to conduct genome‐wide phylogenetic analyses. We found that individuals of L. trifolii from pepper and tomatillo populations form a monophyletic group (“PT group”) distinct from the remaining L. trifolii (“non‐PT group”). These results corroborate previous mitochondrial and nuclear datasets and indicate an absence of gene flow between the PT and non‐PT groups. This is consistent with previous work on reproductive isolation and oviposition preferences, and provides substantial evidence that the PT group represents a distinct and previously unrecognized species. The presence of two species within a nominally single pest species has important implications for management. Although there was only weak genetic differentiation between geographically disparate groups of non‐PT L. trifolii , a monophyletic group of Chinese specimens was found in a coalescent‐based analysis that is concordant with the history of invasions in Asia. Our study provides important new insight into geographic and host‐associated structure in L. trifolii .

Identification of the geographic origin of invasive species can be critical to effective management and amelioration of negative impacts in the introduced range. Liriomyza huidobrensis is a polyphagous leafmining fly that is a devastating pest of many vegetable and floriculture crops around the world. Considered native to South and possibly Central America, L. huidobrensis became invasive in the 1980s and has since spread to at least 30 countries on five continents. We used phylogeographic analysis of over 2 kb of mitochondrial cytochrome oxidase I and II sequence data from 403 field‐collected specimens from both native and introduced populations to investigate the geographic origins of invasive L. huidobrensis worldwide. Within South America, there was substantial genetic variation, as well as the strong phylogeographic structure typical of a native range. In contrast, leafminers from the introduced range and Central America all contained little genetic variation and shared the same small set of haplotypes. These haplotypes trace to Peru as the ultimate geographic origin of invasive populations. Central America is rejected as part of the original geographic range of L. huidobrensis. Within Peru, the primary export region of Lima shared an extremely similar pattern of reduced haplotype variation to the invasive populations. An additional 18 specimens collected at US ports of entry did not share the same haplotype profile as contemporary invasive populations, raising perplexing questions on global pathways and establishment success in this species.

Two new species of bryobiont flea beetles (Coleoptera: Chrysomelidae: Galerucinae: Alticini) from Dominican Republic are described and illustrated: Andersonaltica neiba sp. nov. (Sierra de Neiba) and A. villabarrancoli sp. nov. (Sierra de Baoruco). New species are compared morphologically with each other. Unusual intraspecific variability of A. villabarrancoli is reported. To obtain additional data in understanding the similarities between the specimens of A. villabarrancoli, we sequenced the Cytochrome oxidase I barcode region of adults and larvae. In all cases, the sequences are identical suggesting that the specimens in questions are conspecific.