Whether insects (Insecta) have the subjective experience of pain is difficult to answer. Recent work in humans demonstrated that the experience of pain occurs due to the activation of a “pain network” that integrates nociceptive sensory information, memory, emotion, cognition, and self-awareness. In humans, the processing of nociceptive sensory information alone does not produce the subjective experience of pain. Insect nociception is processed largely in parallel in two higher-order areas in the brain: the mushroom bodies and the central complex. There is little evidence of a coordinated pain network that would integrate these two areas with each other along with other traits thought to be important for a pain experience in humans. However, it is difficult to exclude the possibility that insects could have a modest pain experience using a less integrated neural circuit. This possibility seems unlikely, however, because even a modest experience would require some neuronal investment. It is unclear whether insects would benefit from such an investment. Recent work in artificial intelligence suggests that relatively simple, cost-efficient circuits can produce adaptive behaviours without subjective experience. Given our current understanding of insect behaviour, neurobiology, and evolution, the likelihood that insects experience pain is low.

The phylogenetic relationships among the members of Macronematinae (Trichoptera: Hydropsychidae) have long been debated and often revised. Our study based on a large subunit (28S) nuclear ribosomal DNA (D2 expansion fragment; 464 base pairs) of gene sequences found all genera to be monophyletic except for the genus Polymorphanisus Walker, which produced two clades in accordance with its species groups established using morphological characters. Phylogenetic reconstruction based on mitochondrial cytochrome oxidase I (658 base pairs) found the same monophyletic relationships, however, except for the genera Polymorphanisus and Macrostemum Kolenati. The placement of the genus Leptonema Guérin-Méneville as the basal clade in the subfamily was also ruled out, which is consistent with previous morphological findings. The monophyly of two previously recognised tribes (Macronematini and Polymorphanisini) was not supported. We also found that the genera Centromacronema Ulmer, Baliomorpha Neboiss, and Macronema Pictet are most closely related, having three head setal warts on the vertex of the head and unsegmented inferior appendages of male genitalia as their synapomorphies. Our study supported the hypothesis of close relationship of the genera Amphipsyche McLachlan and Protomacronema Ulmer with the morphological synapomorphies: absence of a forewing discoidal cell and the presence of elevated head carinae on the larvae. Some notable evolutionary novelties in the structure of adults in various lineages of this subfamily include reduction of maxillae and labium, reduction and loss of a discoidal cell and evolution of a c-sc crossvein in each forewing, fusion of segments in each male inferior appendage, and evolution of dark colour patterns in the forewings. Also, the head setal warts, which are unique organs in Trichoptera, evolved towards a decreasing number in the subfamily. This first molecular phylogenetic study, covering most genera in Macronematinae and including an interpretation of 12 key evolutionary novelties, provides an important basis for resolving long-standing questions regarding phylogenetic relationships and classification of genera and species and helps lay a stronger foundation for inference of testable hypotheses about functional traits for species of this common and widespread subfamily.

Rose gall wasps, Diplolepis Geoffroy (Hymenoptera: Cynipidae), induce structurally distinct galls on wild roses (Rosa Linnaeus; Rosaceae), which provide gallers with food and shelter. These galls are attacked by a wide variety of micro-hymenopterans, including Periclistus Förster (Hymenoptera: Cynipidae), which act as inquilines. Both Diplolepis and Periclistus are difficult to distinguish based on adult morphology, instead the structural appearance of galls is often used to distinguish species. Using the mitochondrial gene cytochrome c oxidase subunit I, we tested the species boundaries and built phylogenies of both Diplolepis and Periclistus. The molecular results have largely supported the validity of species described in the literature, with notable exceptions in four species groups. Periclistus exhibits a divide between the Palaearctic and Nearctic clades, and ranges from specialists to generalists in terms of host specificity. While it is premature to enact any taxonomic changes without additional molecular markers, this incongruence between morphological and molecular data indicates these groups need taxonomic revision and gall morphology alone may be inadequate to delimit species.

Density-dependent habitat selection models inherently rely on the negative relationship between population density and mean fitness in different habitats. Habitats differing in quality, such as different food sources or habitat structure, can have different strengths of density-dependent relationships, which can then affect patterns of density dependence in habitat selection. We tested the hypothesis that density dependence in fitness dictates the patterns in density-dependent habitat selection: individuals should prefer higher-quality habitat over lower-quality habitat. We used controlled experiments with red flour beetles (Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)) to measure density dependence of fitness and to examine density-dependent habitat selection by beetles in wheat (Triticum Linnaeus (Poaceae)), corn (Zea mays Linnaeus (Poaceae)), and soy (Glycine max (Linnaeus) Merrill (Fabaceae)) flour habitats. Despite large differences in fitness between habitats (fitness was the highest in wheat flour, lower in corn flour, and zero in soy flour), beetles showed only weak preference for wheat over corn flour and for corn over soy flour, but showed strong preference for wheat over soy flour. These preferences were the strongest at low density. This study gives insight into the relationship between habitat quality and density-dependent habitat selection in flour beetles.

Enaphalodes rufulus (Haldeman) (red oak borer; Coleoptera: Cerambycidae) is a native wood borer that colonises and develops in oaks (Quercus Linnaeus; Fagaceae) across southeastern Canada and the eastern United States of America. It is rarely considered a pest because it normally occurs at low population density levels in stressed or dying oak trees. In the late 1990s and early 2000s there was a large, historically unique outbreak of E. rufulus in the Ozark mountains of Arkansas and Missouri, United States of America. This outbreak provided an opportunity to investigate within-tree spatial distribution of attacks during unusually high insect population levels. Fifty trees from northern Arkansas were felled and destructively sampled. The locations of attack sites by female E. rufulus were standardised across varying heights and diameters for comparison across trees. Attack sites showed a significant clustered pattern within trees. Attack sites were aggregated towards the lower and middle bole, and on the south-facing side of trees. This pattern has been seen in other insects, including wood borers, and is potentially related to differences in temperature. These patterns of ovipositional behaviour in outbreak situations have implications for E. rufulus resource partitioning and facultative intraguild predation among larvae.

Cranberry (Vaccinium macrocarpon Aiton (Ericaceae)) requires insect pollen vectors to maximise fruit yield. In many areas, commercial producers use managed bees (Hymenoptera: Apidae) to supplement native pollinators. On the island of Newfoundland, Newfoundland and Labrador, Canada, due to the small number of available honey bee hives and import restrictions on commercially reared bumble bees, the use of supplemental pollinators is rare. Four farms were studied for two years to identify key pollinators and determine the relationship between fruit yield and bee abundance. The most commonly collected bees were species of Bombus Latreille (Hymenoptera: Apidae), which buzz-pollinate and are likely the primary pollinator on these farms; thus, fruit yield was examined with respect to total Bombus abundance. Stigma loading was also used as a measure of pollinator effectiveness. Contrary to expectation, there was no relationship between Bombus abundance or stigma loading and either fruit set or weight, but there was significant year-to-year variation. Other factors were likely more important in determining yield, and further research is needed to identify those. Under current conditions, native bees provide ample pollination services for maximal yield.

This study aimed to determine differences in activities between two male morphs of the dung beetle Copris acutidens Motschulsky (Coleoptera: Scarabaeidae) during the reproductive period and to examine the size distribution of reproductive males that stayed in nests. The activities of two male morphs distinguished by a threshold value of body size were compared with those by horn length. Regardless of body size or horn length, earlier activity of minor males was observed during the reproductive period. The sex ratio showed the greatest female bias when minor males were the more abundant than major males, indicating that minor males were the most active when competition was the weakest and these could avoid direct combat with major males. In morphs distinguished by horn length, more major males than minor males stayed in nests with females although the major males became the most active from the middle of the reproductive period. Thus, longer horns may directly confer a competitive advantage to males, enabling them to stay in nests with females, whereas early activity of minor males does not always indicate the effect of horn length directly. Therefore, this behaviour may occur regardless of whether the morphs differ in body size or horn length.

Global change research has shown how altering factors like temperature and precipitation can impact insect ecology. However, despite global changes in wind patterns, the effects of altering wind have been relatively unexplored, and even less is understood about indirect effects on insects. To better understand indirect effects of wind on pea aphids (Acyrthosiphon pisum (Harris); Hemiptera: Aphididae), we performed two experiments using different techniques for simulating mechanical stimulation effects from wind. First, we used either a brush or leaf to simulate plant-to-plant contact caused by wind. Then we tested the indirect effects of wind by distinguishing between wind and wind plus plant contact produced by adjacent plants. In the first experiment, aphid fecundity was reduced on plants with the leaf-to-plant treatment compared to the control. In the second experiment, wind treatments reduced pea aphid fecundity, but wind did not interact with plant density. Our results further the idea that altering wind patterns can influence plant–insect interactions. We also show that more research is necessary to disentangle how and why wind indirectly influences herbivores. Future research should focus on how pea aphid responses to wind change due to the methodology of wind exposure and interactions with additional biotic and abiotic factors.

Western hemlock, Tsuga heterophylla (Rafinesque) Sargent (Pinaceae), trees growing in a clonal, commercial seed orchard on Whidbey Island, Washington, United States of America were assessed for Adelges tsugae (Annand) (Hemiptera: Adelgidae) infestation levels to determine whether there was any evidence of resistance to this herbivore. Join-count statistics revealed that A. tsugae infested trees were not clumped, but instead were randomly distributed throughout the seed orchard. Chi-square analyses suggested that there is a genetic basis for different levels of A. tsugae infestation among the genets represented in the orchard. However, since none of the genets were completely free of A. tsugae infestation, differences among genets seem to be related more to susceptibility or tolerance than complete resistance. Among the 17 genets that had five or more ramets in the seed orchard, only one had more than one ramet free of A. tsugae. That genet had four of five ramets that were free of A. tsugae. However, it is not possible to say whether that was due to chance or inherent tree characteristics that make it less susceptible to A. tsugae infestation.

We describe the first dragonflies (Odonata: Anisoptera) from the early Eocene Okanagan Highlands of far-western North America from nine fossils. Six are assigned to five species in four new, named genera of Aeshnidae: Antiquiala snyderaenew genus and species, Idemlinea versatilisnew genus and species, Ypshna brownleeinew genus and species, Ypshna latipennatanew genus and species, and Eoshna thompsonensisnew genus and species; we treat one as Aeshnidae genus A, species A; one is assigned to Gomphidae: Auroradraco eosnew genus and species; and we treat a ninth, fragmentary fossil of unknown family affinity as Anisoptera indeterminate genus A, species A, which represents a seventh genus and eighth species. The dominance of Aeshnidae is consistent with other Paleocene and Eocene fossil localities. Auroradraco eos is the only fossil Gomphidae in the roughly 66-million-year gap between occurrences in mid-Cretaceous Burmese amber and the early Oligocene of France. Ypshna appears close to Parabaissaeshna ejerslevense from the early Eocene Fur Formation of Denmark; this is not surprising given Holarctic intercontinental connections at this time and a growing list of insect taxa shared between the Okanagan Highlands and the Fur Formation.

Larvae of Cochylis hospes (Walsingham) (Lepidoptera: Tortricidae) (banded sunflower moth) are a primary source of insect damage to seeds of cultivated sunflower, Helianthus annuus Linnaeus (Asteraceae), in North America. Field trials were used to evaluate seed damage under natural infestations for panels of publicly released male lines, publicly derived hybrids (females crossed to one common male parent), and commercial hybrids over a total of four years. For trials in 2013–2014 including 17 male lines, seed damage ranged from 3% to 19%. The least damaged male, RHA 266, was statistically similar to one other male, RHA 455. Three commercial hybrids used as checks also received very little seed damage (< 5%). In trials during 2016–2017, hybrids created by pollinating 15 different female lines with RHA 266 showed 4–14% damage. Data from female parents explained about 28% of variation in seed damage for the hybrids. Results confirm cultivated sunflower has greater variation in susceptibility to C. hospes than previously believed, and that seed damage to inbred lines provides some predictive power for hybrids. Though breeding for resistance to C. hospes seems possible, it may be too labour-intensive without relating resistance to more easily measurable traits or genetic markers.

We report the detection and adventive establishment of the samurai wasp, Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae), a candidate classical biological control agent for the invasive Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), in southwestern Ontario, Canada. Nine naturally laid, field-collected pentatomid egg masses were collected in 2017 and 2018, and two of these egg masses, belonging to Halyomorpha halys and Podisus maculiventris (Say) (Hemiptera: Pentatomidae), produced adults of T. japonicus. The identification of T. japonicus was confirmed using DNA barcoding as well as morphological characteristics. The remaining egg masses yielded adults of the native Telenomus podisi Ashmead (Hymenoptera: Platygastridae) and Anastatus reduvii (Ashmead) (Hymenoptera: Eupelmidae).