The semaphorin gene family plays important roles in axonal guidance in vertebrates and invertebrates. Semaphorin 2a, a member of the semaphorin family, belongs to class 2, which is found only in invertebrates. In our study, semaphorin 2a was cloned from the ant Polyrhachis vicina Roger. The full length of P. vicina semaphorin 2a (Pv-sema-2a) is 2763 base pairs (bp) and it contains a 5′-untranslated region (UTR) 92 bp long and a 3′-UTR 521 bp long. The open reading frame of Pv-sema-2a encodes a 716-amino-acid protein with a predicted molecular mass of 81.1 kilodaltons. Real-time quantitative reverse-transcription – polymerase chain reaction indicated that Pv-sema-2a mRNA is differentially expressed during P. vicina development, in the whole bodies as well as the heads of different castes. The high mRNA levels in embryos and pupae suggest that Pv-sema-2a plays an important role in ant development.

Within-plant and between-plants distributions of the Cooley spruce gall adelgid, Adelges cooleyi (Gillette), fundatrices were measured in “interior spruce”, Picea glauca × P. engelmannii (Moench) Voss. & Parry (Pinaceae), seed orchards in central British Columbia to develop a quantitative sampling plan. Adelgids (number of fundatrices per shoot) were abundant at the lower and middle crown heights of the tree crowns but scarce at the upper crown height, and more abundant on the ends and central one-third of branches than on the inner portions. The northern and eastern aspects of trees had slightly but significantly more adelgids than did the southern and western aspects, and terminal shoots had more adelgids than did distolateral shoots. Variance was much greater between than within trees. These data were used to create a sampling plan with a sample unit consisting of a single 1-year-old shoot selected from the ends or central area of main branches in the lower or middle portion of each sample tree. Collecting 104 samples required 69 min, and yielded an estimate of the mean number of fundatrices per shoot with a standard error of 10% of the mean.

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is considered oligophagous on Brassicaceae. We determined the preferences and performance of P. xylostella on canola, Brassica napus L., and flixweed, Descurainia sophia (L.) Webb ex Prantl (Brassicaceae), spider-plant, Cleome hassleriana Chod. (Capparaceae), and garden nasturtium, Tropaeolum majus L. (Tropaeolaceae). Females deposited most eggs on B. napus; T. majus was least preferred. The rate of survival from neonate to pupa was highest on B. napus followed by C. hassleriana, T. majus, and D. sophia. The rate of development of female larvae on Brassicaceae was similar to that on non-Brassicaceae; pupal development was slowest on non-hosts. Female pupae were heaviest on B. napus and lightest on D. sophia. Adult females were heaviest when reared on B. napus and lightest on T. majus and D. sophia. Females reared on D. sophia had the smallest forewings; forewing areas for females on other plants were similar. Females reared on B. napus and C. hassleriana lived longer without food than those reared on D. sophia or T. majus. Males reared on T. majus lived for the shortest time without food. This specialist herbivore can exploit a range of food plants, including suboptimal Brassicaceae and species from other families. This trait appears to facilitate survival and reproduction of P. xylostella when preferred food plants are limiting or absent.

Stability (temporal variability, persistence, resilience) was assessed over 8–13 years for subpopulations, populations, and regional populations of Uroleucon rudbeckiae (Fitch) (Hemiptera: Aphididae) in southern Manitoba, Canada. Contrary to expectations, natural populations of this native aphid were not more stable than those of aphids inhabiting crops. Among population parameters, prevalence (proportion of plants infested) proved more effective for quantifying temporal variability than intensity (colony size) or abundance (number of aphids per stem). The parameter “population variability” was a more effective index of temporal variability than the standard deviation of the logarithm or the coefficient of variation. Small differences in temporal variability were detected among populations that varied greatly in size. Population variability declined slightly as spatial scale increased and did not increase consistently over time. Population variability can be considered characteristic of this species in southern Manitoba, having a value of 0.648 ± 0.080 (mean ± standard deviation, n = 5, over 8–13 years) on a scale of 0–1, a high degree of temporal variability. Persistence was not related to temporal variability. Subpopulations were less persistent than populations, and one of five populations did not persist. Small populations were more likely to disappear temporarily. No resilience was detected.

Subsociality involving provisioning for offspring has been reported for one shield bug and three burrower bug species (Hemiptera: Pentatomoidea: Parastrachiidae and Cydnidae: Sehirinae). We present the first report of subsocial behaviour in the burrower bug Adomerus variegatus (Signoret), focusing on manifestations of maternal care, specifically the production of trophic eggs, guarding of offspring, and progressive provisioning. In our study, each female produced an egg mass that included some trophic eggs. Prior to nymphal hatch, females remained in their nests and showed egg mass guarding behaviour. Mothers started provisioning behaviour a few hours after nymphal hatch. Each mother dragged a seed (larger than her body) with her proboscis to the nest as food for the nymphs. These findings suggest that A. variegatus shows maternal-care behaviours similar to those reported in some other pentatomoid species and that trophic egg production and nest provisioning have evolved as interrelated processes.

The diamondback moth, Plutella xylostella (L.), is a global pest of cruciferous crops (Brassicaceae). It has developed resistance to virtually all known insecticides, and biological control has become an important management tool. In North America the parasitoid Diadegma insulare (Cresson) has been used successfully to reduce diamondback moth populations. We document the presence of the α-proteobacterial endosymbiont Wolbachia and its associated bacteriophage WO in P. xylostella and D. insulare and examine the phylogenetic relationships of Wolbachia and WO in both host species. Our results suggest that Wolbachia and WO have been horizontally transferred in this insect–parasitoid system in recent evolutionary history. Knowledge of the dynamics of Wolbachia in P. xylostella and D. insulare may be an important factor in future control of this pest in the field.

To evaluate sociality in small carpenter bees (Ceratina Latreille), we studied the life history and nesting biology of a common eastern North American species, Ceratina (Zadontomerus) calcarata Robertson. Pan-trap and nest collections throughout the active season (May to September 2006) were used to assess C. calcarata’s seasonal phenology and nesting biology in southern Ontario. Adults overwintered in their natal nests. Males emerged in early May and occupied preexisting hollows in twigs and stems. Females emerged from hibernacula 2 weeks later, founding new nests. Nest founding and provisioning occurred throughout the spring; females remained with developing brood through the summer. Complete nests contained, on average, 6.9 offspring, with egg-to-adult development averaging 46 days. Ceratina calcarata is subsocial rather than solitary: mothers are long-lived and nest-loyal, and care for offspring from egg to adulthood. Subsociality is found in all behaviourally classified small carpenter bees, while some species cross the boundary into social life, making Ceratina an important genus for the study of the transition between solitary and social life.

Tests were performed to determine whether combining two thrips lures, ethyl nicotinate (EN) and ethyl isonicotinate (EI), in the same water trap increased the numbers of New Zealand flower thrips (NZFT), Thrips obscuratus Crawford, and onion thrips, T. tabaci Lindeman (Thysanoptera: Terebrantia: Thripidae), caught in the field relative to traps with a single lure. Traps with both lures (1:1 ratio; mixture or separate adjacent vials) caught 5–9 times more female onion thrips (thelyotokous populations are the most prevalent in New Zealand) than traps with EN only (P<0.001), but in similar numbers to traps with EI only. Traps with both lures caught 2–3 times as many male and female NZFT than traps with EI only, but in similar numbers to traps with EN only. Thus, a combination of the two lures in one trap could be used to detect and monitor flying onion thrips and NZFT simultaneously.

Surveys for signs of attack by Asian long-horned beetles, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), currently rely upon visual examination of trees to discover signs of attack. By embedding simulated A. glabripennis oviposition pits and exit holes on open-grown Norway maples, Acer platanoides L. (Aceraceae), we evaluated the effect of sign density, height (below or above 2.5m), and position (bole or branch) when foliage was present or absent on inspector ability to distinguish trees with or without signs. From this, we quantified detectability, or the proportion of trees correctly identified as infested, and determined the time taken to do so. Effectiveness in detecting trees with signs improved when sign density increased, when signs were below 2.5m, and when oviposition pits were located on boles and exit holes on branches. These main findings require some caveats, due to a number of significant interactions. Foliage presence/absence had no apparent influence on effectiveness; possible reasons are provided for this result. Time-to-find curves, which illustrated the proportion of inspectors who accurately identified an infested tree as a function of survey duration, revealed that for most treatment combinations, most infested trees were detected within the first 2 min of survey time. These findings provide baseline data to assist managers in designing effective protocols for ground surveys of A. glabripennis.