Although insects are fundamental to understanding and conserving global biodiversity, they are vastly understudied. Here, we present a national inventory of Costa Rican insects based upon 3.78 million DNA barcodes representing 152 891 Barcode Index Numbers (BINs, proxies for species) from 28 localities sampled from 2017 to 2023 through the national BioAlfa program of Costa Rica. Although only 3.6% of BINs are linked to Linnean species, barcode-based community analyses revealed strong, consistent ecogeographic structure. Clustering of BIN data using bootstrapped Jaccard distances revealed seven distinct mainland assemblages and a distinct island cluster, shaped primarily by Costa Rica’s mountain ranges, elevation, and slope orientation. Separate analyses for Coleoptera, Diptera, Hemiptera, Hymenoptera, and Lepidoptera coupled with analyses focused on some of their largest families (e.g., Braconidae, Cecidomyiidae, Cicadellidae, Erebidae, and Staphylinidae) confirmed these patterns and further revealed extremely high species turnover with most BINs being exclusive to a single region or locality. Our results reveal limited overlap of insect communities across ecosystems, implying that each life zone harbors unique taxonomic assemblages. Large-scale DNA barcoding has detected fine-grained spatial structure, providing a genomic framework for biodiversity monitoring and conservation in diverse tropical regions undergoing rapid environmental change.

Two morphologically unusual new neotropical genera of Miracinae, Paramomirax Whitfield and Fernandez-Triana, and Fusimirax Whitfield and Fernandez-Triana, are here proposed and described. The two new genera differ strikingly from previously known Miracinae in having completely different patterns of desclerotization of the anterior metasomal tergites. Paramomirax , so far known only from paramo vegetation at high elevation in Colombia, is represented by P. peckorum Whitfield, new species. Fusimirax , so far known only from lower elevation forests in the Dominican Republic, is described from three species, F. masneri Whitfield & Fernandez-Triana, new species, F. robusta Whitfield, new species, and F. gracilis , Whitfield, new species. None of the four species has any recorded hosts yet, although all previous Miracinae with known hosts attack leaf-mining and bark-mining moth larvae.

We describe the trophic relationships of tachinid parasitoid flies that attack exophagous, leaf-eating Lepidoptera caterpillars in Área de Conservación Guanacaste (ACG), northwestern Costa Rica over approximately forty years beginning in 1984. The dataset contains more than 34,000 individual tachinid rearings from individual wild-caught caterpillars. Identification of parasitoids and caterpillars up until 2004 was based entirely on morphology. From 2004 onwards most reared specimens were DNA-barcoded and some retroactive barcoding was also carried out with varying degrees of success. Generally, for older specimens, generating good quality-barcodes requires more expensive protocols. Barcoding of reared specimens led to the recognition that many morpho-species were made up of multiple species of flies but those reared from an individual caterpillar were 99.95% a single species. Consequently, estimates of diet breadth of caterpillars and tachinids changed considerably after 2003. The data analysed here were pruned to include only rearings with complete host and food plant data and excluded potentially duplicated rearings and ones whose identification could not be confidently assigned. The cleaned dataset includes 13,735 independent rearings. Chao1 estimates of numbers of tachinid, caterpillar and food plant species suggest that species sampling is 86, 70 and 91 percent complete, respectively. However, this was not the case for bi- and tritrophic interactions which increased linearly with effort. We show that while the tachinids of ACG are more host-specialised than was expected prior to the combined efforts of rearing and barcoding, they have broader host ranges and higher host Shannon diversity indices than either Braconidae or Ichneumonidae. This may be attributable to the effects of the induced host-derived sac enclosing the larvae and their posterior spiracles.

Plant–herbivore–parasitoid systems are poorly studied in the tropics. Enicospilus carmenae Campos and Palacio sp. nov. are described, originating from southern Mexico in the Yucatan Peninsula and establishing a new tri-trophic interaction. This species is a koinobiont larval endoparasitoid of the American silkworm moth caterpillar Zanola verago (Cramer) (Lepidoptera: Apatelodidae) feeding on the shrub Piper neesianum C.DC. (Piperaceae) in a semi-evergreen forest. The host plant P. neesianum had no herbivore records to date, and a single collection event yielded the rearing of a new species of Enicospilus (Ichneumonidae, Ophioninae). Morphological, molecular (COI), biological, ecological, and geographical data are integrated to delineate the new species.

The parasitoid wasp genus Dolichogenidea is currently the second most speciose within the subfamily Microgastrinae (Hymenoptera: Braconidae), with 366 world species known so far, but with hundreds awaiting to be described. Here, the fauna of the Neotropical region is revised, with an emphasis in the Area de Conservación Guanacaste (ACG), Costa Rica. In addition to 23 species previously recorded from the Neotropics, 102 additional species are described as new, increasing the regional and world richness to 125 and 468 species, respectively. All species are diagnosed and described by using a combination of basic morphology (dichotomous key and brief diagnostic descriptions) and, when available DNA COI barcodes, biology (host data and wasp cocoon strategy), and distribution data. Neither morphology, biology, nor molecular data alone were sufficient to unambiguously separate all taxa, as all approaches were found to have limitations, but the combination of all three approaches provided stronger support to species delimitation. Morphology allowed the inclusion of all known species, therefore building a foundation upon which to improve as more molecular and biological data become available and new species are discovered; however, it was not sufficient (or it was very difficult to use) to separate at least 15% of all species keyed out in the dichotomous key. DNA barcoding was better able to separate species, and it is likely to become the most efficient way to identify species in the near future; however, DNA failed to identify 8.3% of the species with molecular data available, in addition to one third of the described species currently lacking molecular data. Biological data is currently the most incomplete, with only 42% of the species having associated host information, with a strong data availability bias towards ACG specimens. A total of 11 Lepidoptera families are here recorded to be parasitized by Neotropical Dolichogenidea, mainly Depressariidae (34% of all host data available), Gelechiidae (17%), Crambidae (14%), Tortricidae (10%), Thyrididae (8%) and Pyralidae (7%). Most of the wasps seem to be monophagous or at most oligophagous, as 56% are known to only parasitize a single host species, whereas 23% parasitize two host species and 10% parasitize three hosts; in almost all cases, the hosts species belong to one genus (or related genera) in the same Lepidoptera family. Most species of Dolichogenidea are found between 400-1,500 m, but a few have been found at higher elevations, including a few examples higher than 3,000 m (Costa Rica) and 4,000-4,100 m in the Andes (South America). The following nomenclatural acts are proposed: 1) the genus Exoryza is synonymized under Dolichogenidea, syn. nov.; 2) a total of 16 species are transferred to Dolichogenidea as comb. nov., one species formerly in the genus Apanteles: Dolichogenideacroceicornis (Muesebeck, 1958) and all 15 species formerly placed within Exoryza (six of them from the Neotropics): Dolichogenideaasotae (Watanabe, 1932), Dolichogenideabelippicola (Liu & You, 1988), Dolichogenideahylas (Wilkinson, 1932), Dolichogenideamariabustosae (Fernandez-Triana, 2016), Dolichogenideamegagaster (de Saeger, 1944), Dolichogenideaminnesota (Mason, 1981), Dolichogenideamonocavus (Valerio & Whitfield, 2004), Dolichogenideaoryzae Walker, 1994, Dolichogenideareticarina (Song & Chen, 2003), Dolichogenidearichardashleyi (Fernandez-Triana, 2016), Dolichogenidearitaashleyae (Fernandez-Triana, 2016), Dolichogenidearosamatarritae (Fernandez-Triana, 2016), Dolichogenideasafranum (Rousse & Gupta, 2013), Dolichogenideaschoenobii (Wilkinson, 1932) and Dolichogenideayeimycedenoae (Fernandez-Triana, 2016); 3) Dolichogenideayeimycedenoae (Fernandez-Triana, 2016) becomes a senior secondary homonym of Dolichogenideayeimycedenoae Fernandez-Triana & Boudreault, 2019; therefore, Dolichogenideacedenoae Fernandez-Triana & Boudreault, 2025 is a replacement name for Dolichogenideayeimycedenoae Fernandez-Triana & Boudreault, 2019; 4) the following 102 species, all authored by Fernandez-Triana & Boudreault, are described as sp. nov.: D.aceituno, D.alanflemingi, D.alejandromarini, D.alerce, D.alexamasisae, D.alexandrei, D.alixhamiltonae, D.amazonas, D.anacamposae, D.andreamezae, D.angelsolisi, D.anikenpalolae, D.anniapicadoae, D.annlisterudae, D.annychaverae, D.antioquia, D.antjevirkusae, D.arenal, D.bernardoespinozai, D.beryllacosteae, D.bradzlotnicki, D.caldas, D.carlosalvaradoi, D.carlosviquezi, D.chichicastenango, D.christinaagapakisae, D.claudiadoblesae, D.dole, D.encruzilhada, D.ericpalolai, D.ericsimoni, D.escobarae, D.felipechavarriai, D.frankjoycei, D.fredhicksi, D.helenedumasae, D.heredia, D.ingredolsonae, D.isabelleae, D.isidrochaconi, D.jaimelewisi, D.jasonkelleyi, D.jennyphillipsae, D.jessiehillae, D.johnrobinsoni, D.jorgecarvajali, D.jorgecortesi, D.josephfridmani, D.joshdarfleri, D.juanmatai, D.junhyongkimi, D.kasiiya, D.katiemccluskeyae, D.kenzabaddouae, D.lacochaparamo, D.leahdennisae, D.limoncocha, D.luishamiltoni, D.luzmariaromeroae, D.machupichu, D.mehdirheljari, D.moniqueae, D.moniquegilbertae, D.ninamasisae, D.nothofagus, D.oiketicus, D.palenque, D.papallacta, D.paulfryi, D.pedroleoni, D.puschendorfi, D.putumayo, D.puyo, D.rexhamiltoni, D.robertofernandezi, D.robinsherwoodae, D.robmacewani, D.robpringlei, D.rociocordobae, D.rodrigogamezi, D.ronaldzunigai, D.rubymacpearsae, D.rudyamadori, D.sallydaleyae, D.sarahoconnorae, D.scottmilleri, D.shelleymcsweeneyae, D.sigifredomarini, D.stephmae, D.stevestroudi, D.susanabramsae, D.teremariae, D.tiboshartae, D.timrichi, D.tomdaleyi, D.tristanpalolai, D.tucuman, D.verobrondexae, D.virgendelparamo, D.weaversway, D.yungas, D.yvesbraeti.

Are parasitoids less likely to find their Lepidoptera hosts on non-native hostplants than native hostplants? We predicted that with longer periods of coevolution between herbivores and the plants they consume, the parasitoids that provide top-down control would be more attuned to finding their hosts on native plants. To test this hypothesis, we collected immature stages of sulfur butterflies (the cloudless sulfur (Phoebis sennae) and the orange-barred sulfur (Phoebis agarithe) over a three-year period (2008–2011) from native and ornamental hostplants in the genus Senna in three different parts of the urban landscape of Miami, Florida, USA. We reared the immature specimens to pupation and either eclosion of adults or emergence of parasitoids and compared the levels of parasitization among the three areas, and among native vs. exotic hostplants. We found, contrary to our prediction, that caterpillars feeding on non-native leguminous hostplant species were more likely to be parasitized than those feeding on native hostplants. We discuss this surprising finding in the light of recent findings in other plant/herbivore/parasitoid systems.

The south coast of the UK features a number of habitats rich in ground-nesting aculeate wasps and bees. Many of these are in predominantly sandy areas due to nesting requirements, but adjacent heathland may be especially critical in providing rich flower sources for these insects. A surprisingly small transition zone between Hard Cliff and Maritime Heath habitats was found to support an unusually rich local fauna of ground-nesting bees and wasps, near the top of a promontory known as Carn Du, SE of Lamorna Cove in south-western Cornwall. In an area of partly exposed sandy soil measuring approximately 20 m2, more than twenty species (ten solitary bees, 10 aculeate wasps) were found during summer 2024, along with a handful of rarely observed species. We report the species found nesting there and illustrate many of them via field photographs.

Wing interference patterns (WIPs) are color patterns of insect wings caused by thin film interference. Thin film interference is the same phenomenon responsible for the refracted spectral colors sometimes visible on soap bubbles. Insect WIPs are static patterns due to the variable thickness of wing membranes and the colors produced depend on the thicknesses of wing membranes. While WIPs have been studied in several taxa of small insects, they have not been broadly adopted by insect taxonomists. We surveyed WIPs in one moderate-sized genus of parasitoid wasps, Parapanteles (Braconidae: Microgastrinae). Using an inexpensive microscope camera set-up and free imaging and analysis software, we detected consistent WIP differences between Parapanteles species. In some cases, WIPs can be used to diagnose sibling species that would otherwise require SEM images to differentiate or DNA barcodes. Wing interference patters are an underemployed character that may be similarly useful in many other taxa of small clear-winged insects.

The parasitoid wasp genusAlphomelonMason, 1981 is revised, based on a combination of basic morphology (dichotomous key and brief diagnostic descriptions), DNA barcoding, biology (host data and wasp cocoons), and distribution data. A total of 49 species is considered; the genus is almost entirely Neotropical (48 species recorded from that region), but three species reach the Nearctic, with one of them extending as far north as 45° N in Canada.Alphomelonparasitizes exclusively Hesperiinae caterpillars (Lepidoptera: Hesperiidae), mostly feeding on monocots in the families Arecaceae, Bromeliaceae, Cannaceae, Commelinaceae, Heliconiaceae, and Poaceae. Most wasp species parasitize either on one or very few (2–4) host species, usually within one or two hesperiine genera; but some species can parasitize several hosts from up to nine different hesperiine genera. Among species with available data for their cocoons, roughly half weave solitary cocoons (16) and half are gregarious (17); cocoons tend to be surrounded by a rather distinctive, coarse silk (especially in solitary species, but also distinguishable in some gregarious species). Neither morphology nor DNA barcoding alone was sufficient on its own to delimit all species properly; by integrating all available evidence (even if incomplete, as available data for every species is different) a foundation is provided for future studies incorporating more specimens, especially from South America. The following 30new speciesare described:cruzi,itatiaiensis, andpalomae, authored by Shimbori & Fernandez-Triana; andadrianguadamuzi,amazonas,andydeansi,calixtomoragai,carolinacanoae,christerhanssoni,diniamartinezae,duvalierbricenoi,eldaarayae,eliethcantillanoae,gloriasihezarae,guillermopereirai,hazelcambroneroae,josecortesi,keineraragoni,luciarosae,manuelriosi,mikesharkeyi,osvaldoespinozai,paramelanoscelis,paranigriceps,petronariosae,ricardocaleroi,rigoi,rostermoragai,sergioriosi, andyanayacu, authored by Fernandez-Triana & Shimbori.