The phenological behaviours of temperate insects can be highly controlled by photoperiod. Some foundational studies of the mountain pine beetle, Dendroctonus ponderosae (Hopkins) (Coleoptera: Curculionidae), documented a diurnal emergence rhythm that was asynchronous with maximum daily temperatures in the field and persisted under constant temperature and light conditions. In the 1970s, researchers hypothesised that this emergence rhythm was regulated by an endogenous circadian mechanism. Reflecting upon these historical data, we consider that a diurnal pattern of D. ponderosae emergence may result from photoperiodic entrainment of the circadian clock during the immature stages. Mechanistically, we suggest that the long-wavelength-sensitive opsin that we previously found to be expressed across D. ponderosae life stages could mediate, from beneath the bark, the input of light–dark cycle cues that are usually required for entrainment of the insect circadian clock.

Re-examination of the male biting midge of Lebanoculicoides daheri Choufani, Azar, and Nel (Diptera: Ceratopogonidae), in 127 million-year-old Lebanese amber, revealed further features and details of morphological, phylogenetic, and bionomic importance. The phylogenetic position of the fossil genus Lebanoculicoides Szadziewski as the sister group of all remaining extant and extinct Ceratopogonidae is confirmed. A revised key to all four known species of this genus is provided. A permanently erect antennal plume is hypothesised as an additional synapomorphy of Austroconops Wirth and Lee and two Cretaceous fossil genera, Minyohelea Borkent and Archiaustroconops Szadziewski. The presence of a hind tibial comb and more distal row of spines is considered a synapomorphy of all Culicomorpha other than Chironomidae, with some secondary losses within this group.

Insect-encoded cellulolytic plant cell wall hydrolases have thus far been found mostly from glycosyl hydrolase family 5, 9, 10, and 45. We now report the first evidence for genomic encoding of family 12 glycosyl hydrolases in vascular feeding Psyllidae (Hemiptera) and Nematoda. The genes were identified in three psyllids (Acanthocasuarina muellerianae Taylor, Pachypsylla venusta (Osten-Sacken), and Diaphorina citri Kuwayama) and a root tip feeding dagger nematode (Xiphinema index Thorne and Allen; Dorylaimida: Longidoridae). While the final gene products were highly similar, the genomic intron structure varied, having a 2 kB intron in P. venusta, a 283 base-pair intron in D. citri, and no intron in X. index. Endoglucanase activity was demonstrated using the D. citri genes in an Agrobacterium Conn (Rhizobiaceae) infiltration-based plant expression system. The presence of family 12 endoglucanases in this set of insects suggests a specific role in facilitating feeding on vascular tissue.

Mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae), adults fly to disperse before host colonisation. The effect of flight on reproduction was tested by comparing the number and quality of offspring from beetles flown on flight mills to that of unflown control beetles. Beetles reproduced in bolts of their native host, lodgepole pine (Pinus contorta var. latifolia Engelmann (Pinaceae)), or a novel host, jack pine (Pinus banksiana Lambert (Pinaceae)). Bolts infested by control beetles produced more offspring overall than bolts with flown beetles. The effect of pine species on the number of offspring produced per bolt varied by individual tree. Flown adults produced fewer offspring compared to control parents in all bolts in jack pine regardless of the tree, but tree-level variation was visible in lodgepole pine. An interaction between flight treatment and tree host affected beetle body condition. More offspring emerged from jack pine, but higher quality offspring emerged from lodgepole pine. The offspring sex ratio was female-biased regardless of parental flight treatment. This study reveals trade-offs between flight and reproduction in mountain pine beetle as measured at the level of the bolt.

In 2012, an unexpected outbreak of Lambdina fiscellaria (Guenée) (Lepidoptera: Geometridae) occurred in the Laurentian Mountains, Québec, Canada, known for its harsh climate. We wondered whether the eggs were sufficiently cold hardy to survive there and, if so, how long this outbreak would last. Therefore, we assessed the capacity of the eggs to supercool, to tolerate short exposures to low sub-zero temperatures, or to successfully overwinter in the field. The same assays were performed with eggs from the island of Newfoundland, Newfoundland and Labrador, Canada. The mean supercooling point of eggs from the two populations increased from −40.2 °C in mid-February to −33.7 °C in mid-May. These eggs may also die at sub-zero temperatures above their supercooling point, depending on exposure durations. In the fall of 2012 when eggs were put out in the field, < 10% survived in the Laurentian Mountains, whereas > 70% survived further south. In the spring of 2013, no parasitism was detected in the population. However, the two cold waves that swept across the Laurentian Mountains the preceding winter were likely responsible for the collapse of the population. This study demonstrates that L. fiscellaria eggs may succumb to sub-zero temperatures above their supercooling point under field conditions.

Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), also known as the citrus leafminer, is a serious pest in Citrus Linnaeus (Rutaceae) nurseries in Iran. Few studies have been performed on the life history of this pest on different citrus hosts. In this work, the infestation rate and biological aspects of P. citrella were investigated using four citrus hosts: Valencia orange (Citrus sinensis (Linnaeus) Osbeck), trifoliate orange (Poncirus trifoliata (Linnaeus) Rafinesque), grapefruit (Citrus paradisi Macfadyen), and sweet lemon (Citrus aurantifolia Swingle). Moths preferred laying eggs on leaves with a width ranging from 1–2 cm, and the highest oviposition was observed on the Valencia orange (51.2 eggs/female). The numbers of pupae and infested leaves were significantly higher on C. sinensis and C. aurantifolia. The entire developmental period of the immature stages was 13.8 and 15.4 days in C. aurantifolia and C. sinensis, respectively, while it increased to 21.8 and 24.7 days in C. paradisi and P. trifoliata. The rate of mortality of the immature stage was the highest in these two latter hosts as well (29–31%). Moths showed the highest emergence and longevity on C. sinensis and C. aurantifolia. The results indicate that C. sinensis and C. aurantifolia are susceptible hosts that can be recommended for the mass-rearing of this species in non-chemical pest control programmes.

Population density is often a critical factor in colonisation of trees by bark and wood-boring insects and may determine whether an exotic species is likely to establish and spread. In a manipulative field study, we investigated whether density of the attacking population of an exotic invasive woodwasp, Sirex noctilio Fabricius (Hymenoptera: Siricidae), affected survival and time-to-death of a favoured host tree, Pinus sylvestris Linnaeus (Pinaceae). We introduced mating pairs of woodwasps to stressed P. sylvestris at either high (15 mating pairs, nine trees) or low (two mating pairs, nine trees) density. More trees died, and more quickly, when exposed to the high versus low density of S. noctilio (78% versus 33% of trees). In the high-density treatment, year of tree death was synonymous with production of a S. noctilio F1 cohort (one-year or two-year generation time); this pattern was not as consistent in the low-density treatment. Although sample size was limited, our results indicate that attack density affects S. noctilio colonisation of P. sylvestris.

Aphidius ervi Haliday (Hymenoptera: Braconidae) is a major natural enemy of several agricultural pests in North America. Yet little is known about its overwintering strategy, especially concerning the plastic response to photoperiod and temperature that induce diapause. Information on parasitoid overwintering patterns is of great importance if we aim to predict their phenology and better inform pest outbreak control. Moreover, there is increasing evidence of plastic and genetic changes in overwintering strategies in insect from temperate areas following climate change. We set up a laboratory approach to better understand the factors acting on diapause induction in A. ervi. We studied the diapause incidence in a population from Québec, Canada, using the combination of two temperatures (14 °C and 20 °C) and three photoperiod treatments (10:14, 12:12, 14:10 [light:dark] hours). We found an effect of both factors on diapause incidence; A. ervi expressed close to 95% of diapause at the most fall-like conditions (14 °C, 10:14 [light:dark] hours) and almost no diapause (3.5%) at the most summer-like conditions tested (20 °C, 14:10 [light:dark] hours). This parasitoid species does have the potential to enter diapause in Québec before lethal frosts, despite a recent introduction from France (1960s), where mild winter occurs compared with Québec.

The occurrence of Bursaphelenchus xylophilus (Steiner and Buhrer) (Nematoda: Aphelenchida: Parasitaphelenchidae) (pinewood nematode) in Canada prevents export of wood products, including Christmas trees (Pinaceae), to Europe. A nationwide survey in 1992 extracted B. xylophilus from mature, dead, or dying balsam fir (Abies balsamea (Linnaeus) Miller; Pinaceae), but not young, healthy Christmas trees. Three species known to harbour B. xylophilus are found in Nova Scotia, but incidence of B. xylophilus within these species is unknown. Monochamus Dejean (Coleoptera: Cerambycidae) species were collected from nine and 20 sites, in 2014 and 2015, respectively, using panel traps baited with a Monochamus lure and evaluated for the presence of pinewood nematode using molecular methods after DNA isolation. Beetles were processed for DNA isolation individually in 2014 and in batches (same species and sex from same collection site and date) in 2015. Bursaphelenchus xylophilus was recovered from all three Monochamus species (M. marmorator Kirby, M. notatus (Drury), and M. scutellatus (Say)) captured in Nova Scotia Christmas tree plantations. Percentage of beetles harbouring B. xylophilus varied with species and sex. Fourteen beetle samples were selected and sent for polymerase chain reaction sequencing. Sequencing results indicated that Bursaphelenchus xylophilus found in Nova Scotia are most similar to isolates from Canada (New Brunswick and Québec), the United States of America, and China.

Empirically-based economic injury levels are lacking for pea aphid, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), as a direct pest of dry peas, Pisum sativum Linnaeus (Fabaceae). To address this need, the relationship between pea aphid density and yield of dry pea (cultivar Aragorn) were quantified by encaging pea aphids at varying densities for 17-day infestation periods during 2009 and 2010 in Moscow, Idaho, United States of America. Pea aphid density after infestation at the early reproductive stage of the crop (x) significantly reduced dry pea seed yield (relative weight of US #1 dry peas, y): y = 0.7733 − 0.00998x + 0.000037x2. Economic injury levels were computed based on this relationship and incorporating the cost of control, crop market value, insecticide efficacy, and crop yield potential. The resulting economic injury levels ranged from five to 19 pea aphids per plant at the start of early reproductive growth stages of dry peas. For usability these were converted to sweep net sample size equivalents of 86–307 pea aphids per twenty-five 180-degree sweeps with a standard sweep net. These economic injury levels are applicable in the inland Pacific Northwest, United States of America, where they were developed and likely in other regions with similar climatic and agronomic conditions.

Strawberry decline disease, predominantly viral in origin, was a serious threat to the strawberry (Fragaria x ananassa Duchesne ex Rozier; Rosaceae) fields of Québec, Canada, between 2012 and 2014. Our aim was to monitor the abundance and activity of the main insect vectors: the strawberry aphid, Chaetosiphon fragaefolii (Cockerell) (Hemiptera: Aphididae) and the greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae). First, we compared the effectiveness of two trapping techniques, the yellow sticky trap and the yellow pan trap. Results showed that the sticky traps are more effective in capturing alates in flight. Second, we determined the peak flight period for each of the two vectors in several locations within the province of Québec. Results suggest that the peak abundance of winged C. fragaefolii is during the first two weeks of August, while the peak abundance of T. vaporariorum is in the last two weeks of September. Overall trap captures also found 53 different species of winged aphids, and we documented a new distribution record on commercial strawberry fields in Québec, Aleyrodes spiraeoides (Quaintance) (Hemiptera: Aleyrodidae). Species composition and significant information of flight periods will be useful for the management of virus-transmitting insects associated with strawberry decline disease in Québec.

The primary insect pests in Canadian carrot production are carrot rust fly (Psila rosae (Fabricius); Diptera: Psilidae) and carrot weevil (Listronotus oregonensis (LeConte); Coleoptera: Curculionidae). An integrated pest management programme for these pests exists in Québec and Ontario, where most Canadian carrot (Daucus carota subsp. sativus (Hoffmann) Schübler and Martens; Apiaceae) production occurs. As current carrot insect integrated pest management recommendations are decades old, laboratory and field trials were performed to evaluate the carrot insect integrated pest management recommendations. Carrot weevil populations were evaluated in the laboratory for resistance to the primary product used for control, phosmet. Ontario carrot weevils exhibited negligible mortality when exposed to phosmet compared with > 80% mortality in a susceptible strain. Using data from a carrot integrated pest management programme, weather data was correlated with monitoring and damage data of both pests from historical records. Increased carrot weevil captures were weakly related to increased damage. Carrot weevil damage was reduced by following integrated pest management recommendations in one of three trials. No strong relationship between weather and carrot rust fly captures was identified, suggesting the degree day model for carrot rust fly activity needs revision. In field trials, carrot rust fly damage was negligible despite integrated pest management recommendations for insecticide applications. Future research should include improving carrot weevil monitoring and control and increasing the carrot rust fly action threshold to optimise insecticide applications.

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), also known as the brown marmorated stink bug, is an invasive agricultural and nuisance pest. Knowledge of the life history of insect pests is important for informing pest management activities. Some North American populations of H. halys have two generations per year, and it is suspected that H. halys may have a partial second generation in the Niagara Region of Ontario, Canada. We determined the number of H. halys generations in Ontario by examining the reproductive development of field-caught adult females. The pattern of reproductive development we observed supports the conclusion that H. halys complete one generation per year in the Niagara Region of Ontario. Reproductively active H. halys were captured as early as May and continued until early September, and the peak of reproductively active individuals occurred between 250 and 550 degree days calculated with a sine-wave function and a lower threshold set to 14.17 °C.