The absence of males in 1000 adults examined over a 2 year period, the facility with which unmated females deposited eggs, and the high percentage (86%) of these eggs which hatched are presented as evidence for obligatory parthenogenesis in Cloeon triangulifer McDunnough. It is suggested that the unusually long (June to November) emergence period of the species is a result of parthenogenesis.

In this study, we analysed the applicability of DNA barcodes for delimitation of 79 specimens of 13 species of nonbiting midges in the subfamily Tanypodinae (Diptera: Chironomidae) from São Paulo State, Brazil. Our results support DNA barcoding as an excellent tool for species identification and for solving taxonomic conflicts in genus Labrundinia. Molecular analysis of cytochrome c oxidase subunit I (COI) gene sequences yielded taxon identification trees, supporting 13 cohesive species clusters, of which three similar groups were subsequently linked to morphological variation at the larval and pupal stage. Additionally, another cluster previously described by means of morphology was linked to molecular markers. We found a distinct barcode gap, and in some species substantial interspecific pairwise divergences (up to 19.3%) were observed, which permitted identification of all analysed species. The results also indicated that barcodes can be used to associate life stages of chironomids since COI was easily amplified and sequenced from different life stages with universal barcode primers.

The dynamics of Aphis pomi De Geer (Homoptera: Aphididae) and its predator, Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae), were studied over two seasons in a commercial apple orchard in Nova Scotia. Aphid and predator population dynamics were very different in the two seasons. The most numerous predator in both years was A. aphidimyza. This predator was found in the earliest colonies sampled each season and was present throughout the growing season. In the year with relatively high aphid densities a single peak in aphid and predator density was seen in mid-July, just prior to maximum predation rate. The predator’s numerical response resulted in delayed density dependence in predation rate. In the year of low aphid densities, predator and prey dynamics appeared uncoupled, and a higher rate of colony turnover may have been caused by other predators such as mirids. Aphidoletes aphidimyza tended to aggregate oviposition in high-density aphid colonies, but this aggregation resulted in predation that was only very weakly spatially density dependent.

Culex pipiens entered diapause in early July with more than 90% in diapause by mid-August. Onset of diapause in Culex restuans was in early July with greater than 80% in diapause by late July. The incidence of diapause in C. pipiens increased when larvae were reared at low temperatures or high densities under similar photoperiod conditions. Diapausing adult females of C. pipiens and C. restuans had ratios of follicle:germarium length of less than 2.00:1.00. Ovarioles of recently emerged diapausing C. pipiens developed to the nondiapause stage in 3–4 weeks when held at 25 °C and a photoperiod of 16L:8D. Ovarioles of diapausing C. pipiens in the field did not develop to the nondiapause state before females left their overwintering sites in the spring.

The false chinch bug, Nysius ericae (Schilling), was reared successfully in clear polystyrene containers in the laboratory. Nymphs were fed hulled sunflower seeds and radish slices; adults were fed hulled sunflower seeds and seedlings of Brassica juncea mustard or B. napus canola. Eggs were laid in rolls of compacted cotton, stored at 5 ± 1°C, and brought out to room temperature for hatching.

The correct identifications of North American species of leafhoppers of the genus Macrosteles (sensu lato) are important because of the economic significance of one of them as a carrier of a virus disease of many species of plants. In the past, such identifications have been difficult to make because the extent of the variation in colour, markings, and structure that occurs has not been appreciated fully, because some species were misidentified in previous revisions, and because there were a number of unrecognized species in the fauna.

Mosquito larvae tagged with radioactive P32 were released in woodland pools to identify their predators. Fourteen of 38 species of aquatic insects collected had ingested tagged Aedes. The leading predators were Dytiscidae and one species each of Gyrinus, Gerris, Callicorixa, and Asynarchus. Records are new for Asynarchus sp., Callicorixa audeni Hung., Dytiscus sp., Gerris buenoi Kirk., and Ilybius discedens Shp. The mosquito predator fauna at Cordova Mines and that of previously studied pools at Chatterton, Ontario, are compared.

The alfalfa leafcutting bee, Megachile rotundata (Fab.), is an important pollinator of alfalfa in western Canada and is widely utilized for alfalfa seed production (Richards 1984). As a beneficial insect, the alfalfa leafcutting bee must be considered, along with the honey bee, Apis mellifera L., as a non-target organism of importance in evaluations of potential microbial control agents for use against major insect pest species on the Canadian prairies.

Following aerial application of a Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), nuclear polyhedrosis virus (NPV) product called Virtuss on four plots in 1982, observations were made to determine the impact of these treatments in 1983 and 1984. Treated plots as well as buffer zones between and adjoining the treated plots, and three of the four check plots established in 1982, were monitored. The NPV appeared to have spread from the treated plots to adjoining areas in 1982, effectively reducing the Douglas-fir tussock moth population. This observation suggests that a strategy of spraying alternate swaths of Douglas-fir tussock moth infested stands with this viral insecticide may effectively initiate an epizootic that would control the population at a reduced cost.

A naturally occurring NPV epizootic decimated the Douglas-fir tussock moth population in the three check plots in 1983, but severe tree mortality occurred in two of these plots with 60 and 62% of sample trees dead in 1984. Light tree mortality was noted in 1984 in two of the four treated plots with 4 and 7% of sample trees killed. It is concluded that the virus treatments in 1982 were successful in preventing tree mortality.

A trap for flying insects that incorporates some of the principles described by Williams and Milne (1935) and Chamberlin and Lawson (1910) was constructed. It consists basically of two conical nets that rotate in a horizontal plane around a central axis that is driven by an electric motor through a series of pulleys. The efficiency of the trap is not affected by wind as an increased airflow through one net is balanced by a decreased airflow through the other. It is green in colour to blend with its surroundings. The trap (Fig. 1) is 5½ feet high at the centre. It has three main sections (Fig. 2): the framework, the drivillg mechanism, and the nets.

Esterase banding patterns in native polyacrylamide gel electrophoresis, squash silver leaf (SSL) induction, and tomato yellow leaf curl begomovirus-Sardinia (TYLCV-Sar) transmission capability were investigated to evaluate variations among populations of Bemisia tabaci (Gennadius) from Italy and to relate their distribution to their geographic origin. Adults of the B biotype, adults of the Q-like biotype (which is similar to a Spanish biotype), and adults without esterase bands were found. The B biotype has been found in Italy since 1989. Two populations, including mainly B and Q-like biotypes, showed similar TYLCV-Sar transmission efficiency, independent of esterase banding pattern. Only populations from Liguria and Sardinia, which contained almost exclusively B-biotype individuals, were able to induce SSL. We observed that adults of the B biotype are widespread in greenhouses of northern Italy and Sardinia, whereas those of the Q-like biotype are present only in fields of southern Italy. These results suggest that the B biotype of B. tabaci was introduced into Italy likely while trading ornamental plants, whereas the Q-like biotype is native to the Mediterranean region.

Fifteen months after an intense forest fire, the fauna of carabid beetles in burnt and unburnt sites was sampled using pitfall traps to detect the indirect effects of fire on carabids caused by habitat change. Traps were installed in burnt and unburnt sites in which the dominant tree species before the fire was either spruce or aspen. The most commonly caught species was Pterostichus pensylvanicus which was captured more frequently in unburnt sites, but was not affected by dominant tree species; a similar pattern of distribution of captures was found for Carabus taedatus. Harpalus laticeps was captured only in burnt sites. P. lucublandus and Dicaelus sculptilis upioides were most commonly caught in the unburnt aspen site, while Pterostichus adstrictus was most commonly caught in the burnt spruce site.

The effect on stream invertebrates of carbaryl (Sevin-4-oil®) applied at a rate of 840 g A.I./ha for spruce budworm suppression in Maine was studied. Three streams in each of three different treatment areas were monitored: streams in areas sprayed with carbaryl for the first time, streams in areas sprayed 2 consecutive years, and streams in unsprayed areas.

Initial postspray response was an increase in drift up to 170× in treated streams. Benthos samples showed significant declines among Plecoptera, Ephemeroptera, and Trichoptera on subsequent sampling dates. Plecoptera did not repopulate any treated stream by 60 days after treatment. Streams treated for the second consecutive year had very low prespray Plecoptera populations compared with those unexposed to carbaryl. Diptera, with the exception of Microtendipes, and Oligochaeta were unaffected.

The upper limit for continuous development of Pleolophus basizonus lies between 25° and 30 °C since all stages develop at the former temperature and larval mortality is complete at the latter temperature. The lower limit lies between 5.5° and 10 °C, since an eonymphal diapause occurs at 5.5 °C. Between these extremes, diapause incidence varies inversely with temperature. The photoperiod experience of the parent has no effect on diapause in the progeny when the latter are reared at 15° and 18 °C, but there is an inverse relation between parental photoperiod experience and progeny diapause incidence at 10 °C. Although larvae and pupae also survive 3 months at 2 °C, most individuals probably overwinter in eonymphal diapause and their diapause requirements are fulfilled in 3 weeks at 2 °C. The incidence and rate of post-diapause development is directly related to temperature.

The invasion of a Douglas-fir seed orchard by host-specific seed chalcids immigrating from the surrounding plantations of Douglas-fir has been monitored for a 10-year period. The orchard cone crop was entirely harvested every year to prevent the establishment of a resident chalcid population. Over the 10 years the percentage of infested seeds resulting from the immigration of seed chalcids ranged from 0.88 to 91.0%. A model to forecast the importance of annual seed orchard infestation by immigrating populations is proposed. This model is based on passive diffusion of females emerging in the surrounding plantations with a downwind drift. Only a few plantations located within a radius of 5 km from the orchard appeared to contribute significantly to orchard infestation. Settlement of Douglas-fir orchard in regions with low density of conspecific trees and annual harvest of cones are suggested to limit the importance and regularity of seed chalcid damage.

Adults and deutonymphs of Najadicola ingens (Koenike) are redescribed and larvae are described for the first time. In light of larval, deutonymphal and adult character states, the phylogenetic relationship of Najadicola with genera in the families Pionidae and Unionicolidae is re-evaluated and transfer of the subfamily Najadicolinae to Pionidae is proposed. Original life history information is presented to supplement existing literature. Parasitism by larval N. ingens on an adult chironomid of the genus Polypedilum is reported. The unique behavioural and morphological characteristics of members of Najadicola suggest that mussel parasitism evolved independently from a parallel adaptive sequence in the genus Unionicola.

The adults of Chrysopa harrisii Fitch, which are not predaceous, overwinter in a state of reproductive diapause. During both the dormant and the reproductive periods they remain dark green, a colour apparently adapted to the species’ occurrence on conifers. Two to three generations per season are possible in the Ithaca, N.Y., area.

At 75°F, which is the optimum constant temperature for development and survival, the time from oviposition to adult eclosion is 29 days. Theoretical thresholds for development of all stages are relatively high, between 50° and 57°F, and development from egg to adult requires 566 heat degree days.

In the laboratory, the critical photoperiod for diapause induction is between LD 13:11 and LD 14:10; short days maintain diapause for approximately 45 days (at 75°F); long days terminate diapause. Both newly-emerged and reproductively-active adults are extremely sensitive to diapause-inducing photoperiods. In the field, all adults emerging on 5 September or later enter diapause and it appears that diapause induction in the Ithaca population begins in the latter part of August. Short days maintain diapause until the end of December, and neither long days, increasing day lengths, nor low temperatures play a role in hastening diapause termination in nature.

In timing its vernal reproduction, C. harrisii has evolved a strategy that combines an early-ending diapause with an apparently relatively high temperature threshold for post-diapause development. Therefore, although diapause ends around the winter solstice, heat accumulation is prevented until much later, when temperatures are relatively high.

The warehouse beetle, Trogoderma variabile Ballion (Coleoptera: Dermestidae), is a stored-product pest with scant information on its cold tolerance. Ninety-two per cent of larvae reared in isolation at 30 °C went into diapause in the seventh instar, the remaining 8% emerged as adults in 50 days. Diapausing larvae died after 142 days in the 10th instar. The cold tolerance at 0 °C from highest to lowest was; old larvae>pupae>adult=young larvae>eggs. The LT50 (lethal time for 50% of the population) for grouped (non-diapause) non-acclimated old larvae at 0 °C, −5 °C, −10 °C, −16 °C, and −19 °C were; 20, 11, 5, 1, and 1 day, the LT95 were; 38, 15, 10, 5, and 1 days, respectively. The LT50 for isolated (diapausing), cold-acclimated old larvae at the same temperatures were; 275, 125, 74, 26, and 18 days, and the LT95 were; 500, 160, 100, 45, 20 days, respectively. The supercooling point (SCP) of different stages of non-acclimated insects ranged from −25.3 °C (eggs) to −16.1 °C (young larvae). The most cold hardy stage, isolated and acclimated old larvae, had a SCP of −24.9 °C. The potential of using low temperatures to control T. variabile is discussed.

Maris Kestrel kale, Brassica oleracea L., was planted and sampled in two locations during 1977–78. The aphids Brevicoryne brassicae (L.) and Myzus persicae (Sulzer), syrphids in the genera Syrphus and Scaeva, the cecidomyiid Aphidoletes aphidimyza (Rond.), the parasite Diaeretiella rapae (M'Intosh), and the fungus Entomophthora aphidis Hoffman were observed in the samples. A volumetric technique for assessing aphid numbers was developed and evaluated. Peak numbers of B. brassicae differed by an order of magnitude between plots, but the pattern of monotonic increase in the spring, followed by an abrupt decline in the rate of increase, a mid-summer peak, and an autumn population decline was consistent throughout. The first major decline in the rate of increase of B. brassicae was correlated with the appearance of A. aphidimyza and syrphid larvae. Declining adult aphid weight, which suggested declining fecundity, increased alate production at high aphid densities, parasite pressure, and leaf fall added to the damping effect of predators. In autumn, cool temperatures and production of sexuals further reduced the rate of increase of B. brassicae.

Species richness and relative abundance of arthropod taxa from an Upper Cretaceous (Campanian: 75 Mya) amber deposit in Alberta are described. About 130 hexapod species have been recognized to date from this deposit, making it the most diverse Cretaceous insect assemblage so far known. Taxa present, in order of abundance, are Hemiptera (66 specimens per kg), Diptera (28), Acari (21), Hymenoptera (13), Aranaea (12), Psocoptera (4), Coleoptera (2), Blattodea (1), Thysanoptera (1), and Trichoptera (0.6). Representatives of Lepidoptera, Collembola, Dermaptera, Mantodea, Phasmatodea, and Ephemeropteraare are also present. In the total of 65 identified families, 15 are extinct. Only one of about 77 genera identified in this deposit is extant. All recognized species are extinct. In comparison, virtually all families reported from Baltic and Dominican Republic ambers are extant, as are the majority of the genera. Morphology and feeding structures are well within the variation seen in modern insects. It is hypothesized that the taxonomic structure of modern insect communities was well established before the end of the Cretaceous and that the structure and interrelationships of insect guilds were also very similar to those of today.