The effects of temperature on rates of oviposition and development of immature stages of Pissodes strobi from Sitka and white spruce were investigated in the laboratory. Maximum rate of oviposition occurred at 20° to 26 °C. Brood development from egg to emergence took 888 and 785 degree-days above a threshold of 7.2 °C for the weevil from Sitka and white spruce, respectively.

Animal and plant enemies undoubtedly play an important part in controlling mosquitoes, but it is fully recognized that a study of these organisms forms only one phase of a very complex subject spoken of generally as natural control. Climate, weather conditions, topography, etc., all have an important bearing on mosquito abundance. Precipitation, whether in the form of rain or snow, and temperatures, exert a vital influence on mosquito populations. If the winter accumulation of snow is heavy, the spring infestation of snow pool and floodwater mosquitoes may be expected to be heavy too.

The genus Aceodromus is redefined on the basis of the type species, A. convolvuli Muma, and a new species, A. asternalis, both of which are described and illustrated. The subfamily Aceodrominae Muma is removed from the Phytoseiidae and synonymized under the subfamily Blattisociinae (Blattisociidae), and reasons for this action are discussed.

This paper describes a tri-trophic analysis of the ecological dynamics of a crop, an insect pest, and a natural enemy of the insect pest. Worldwide wheat (Triticum Linnaeus) (Poaceae) production in 2018–2019 was estimated at over 700 million metric tons in 2018–2019. Wheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), a serious insect pest of wheat, is widely distributed in many parts of the world where wheat production occurs. Macroglenes penetrans (Kirby) (Hymenoptera: Pteromalidae), a parasitoid of S. mosellana, has successfully established in most wheat midge-infested areas. Mechanistic, or process-based, population models were used in this study to assess the interactive population dynamics of the three species, based on their respective life cycles and meteorological factors. The models were validated with survey data from multiple sites over numerous years (1991–2016). These simulation models helped to detail our understanding of the tri-trophic population dynamics and will help guide pest management decisions both prior to the growing season and until wheat heading, when wheat is no longer susceptible to S. mosellana. The associated models also help identify gaps in system knowledge, provide a foundation for evaluating future innovative management options, and evaluate the potential impact of a changing climate.

Male release-recapture experiments show that under natural photoperiod there is no cross attractancy between species of the sympatric pairs E. declarata and E. campestris or E. declarata and E. rockburnei, but that there is between the parapatric pair, E. campestris and E. rockburnei. When the calling periods of E. declarata and E. campestris females are synchronized by photoperiod manipulation there is cross attraction between these two species as well. However, in mating discrimination tests between E. declarata and E. campestris the normally strong bias against interspecific mating is only partially overcome by synchronizing mating activity rhythms. The residual tendency for conspecific mating is more likely due to imperfect synchronization of mating rhythms or differences in close range courtship behavior than to differences in attraction pheromone. Males of all three species are attracted to the same synthetic attractants. The results are consistent with the hypothesis that the attraction pheromones of the three species in the declarata group are very similar and are unlikely to play a major role in reproductive isolation, which is probably effected primarily by differences in circadian rhythms of mating activity.

High-quality habitats presumably have the resources required to sustain relatively high rates of survival and reproduction. We assessed how habitat type and local environmental conditions determine the distribution of individuals of Canthon cyanellus (Coleoptera: Scarabaeidae), an eurytopic dung beetle, according to age category and sexual gonadic maturity. Beetles were surveyed in forest fragments, live fences, and pastures in Mexico. Individuals were categorised into six age categories according to the glandular volumes in males and oocyte number and length in females. Mature females in forest fragments were the most abundant females found among the habitats. Air humidity and soil hardness were positively and negatively related to mature female abundance, respectively. Mature beetles were the most abundant among males, and higher abundance of males occurred in forest fragments than in live fences and pastures. Light quantity was negatively related to the abundance of young males. Compared to forest fragments, females in pastures had larger oocytes. However, sites with higher soil hardness and air humidity had females with lower numbers of oocytes. Our results demonstrate that, although C. cyanellus occurs across a wide range of habitats, forest habitats might host sexually mature individuals, which translates into more effective individual dispersion and potential reproduction.

Microplitis mediator (Haliday), a braconid parasitoid reared on the bertha armyworm, Mamestra configurata (Walker), entered diapause at 16 °C and a 12L:12D (100%) or 14L:10D photoperiod (99%) but not at 16 °C or 21 °C under a 16L:8D photoperiod or at 21 °C and a 12L:12D photoperiod. Diapause development was accelerated by cold treatment; adults emerged from diapause more rapidly with increasing duration of cold exposure at least up to 120 days. The main pupation site was found to be on senescent canola leaves which formed a leaf litter on or near the plants. Nearly all unparasitized fourth-instar hosts (98–100%) were found on host plants, whether the conditions induced diapause or not. Only 16–23 and 0% of parasitoids pupated on host plants under conditions of non-diapause or diapause induction, respectively. Because the pupation site of the parasitoid depends on movement of the host, these results suggest that mature parasitoid larvae modify movement of their host.

Effects of an operational application of Dimilin® on non-target insects were evaluated in eastern West Virginia in 1988 and 1989. Dimilin was applied in 1988 (70,75 g AI per ha). Insects were collected by light-traps at seven pairs of Dimilin-treated and control sites. Lepidoptera experienced the greatest impact, displaying reduced abundance and species richness at treated sites. No effects were observed among Coleoptera, Diptera, or Hymenoptera.

Studies on the parasites of the Swaine jack pine sawfly, Neodiprion swainei Midd., form part of an extensive program designed to assess the factors influencing population dynamics of this important defoliator of jack pine, Pinus banksiana Lamb. Investigations were carried out in the Province of Quebec between 1955 and 1959 near the headwaters of the Gatineau River, Abitibi County, and continued during 1960 and 1961 near the source of the Vermillion River, County Laviolette. In both areas, one of the principal parasites associated with N. swainei was the tachinid, Spathimeigenia spinigera Townsend. Descriptions of the immature stages of this parasite, and details of its behaviour were published previously (Tripp, 1960).

Two new species of Eocene Eomerope Cockerell (Mecoptera: Eomeropidae) are described from the Ypresian Okanagan Highlands deposits of British Columbia, Canada: Eomerope simpkinsaenew species from the Allenby Formation near the town of Princeton, and Eomerope eonearcticanew species from the McAbee locality near the towns of Cache Creek and Ashcroft. Eomerope eonearctica is very close to the coeval Eomerope asiatica Ponomarenko from Primorskiy Kray in Pacific-coastal Russia, consistent with Eocene intercontinental dispersal, which is well documented in numerous plant and animal taxa.

Five cycles of single-plant and progeny-row selection in lines derived from Brassica rapa L. "Tobin" were used to identify plants with incomplete resistance to flea beetles, Phyllotreta cruciferae (Goeze). This line, called C8711, had higher survival, grew larger, and yielded more seed than Tobin when the two lines were compared in field plots at Glenlea, Manitoba, unprotected by insecticide. C8711 without insecticide yielded more seed than Tobin treated with a lindane seed dressing, but less than Tobin treated with carbofuran granules. With carbofuran, which prevents most flea beetle damage, the yield of C8711 was 35% higher than for Tobin. At Saskatoon, Saskatchewan, the differences between C8711 and Tobin were not statistically significant, although the trends were similar to those at Glenlea. C8711 was late maturing, produced small seed, and was not of canola quality. The resistance in C8711 is attributed to a low level of antixenosis, rapid growth at the cotyledon stage, and tolerance to damage during the first 3–4 weeks of growth.

Six new species of Mucroseius having adult females phoretic on adult sawyer beetles of the genus Monochamus are described: Mucroseius nipponensis and Mucroseius squamosus from Monochamus alternatus Hope in Japan, Mucroseius algonquian from three species of Monochamus in eastern Canada and eastern United States, Mucroseius disparisetus from Monochamus titillator (Fabricius) in southeastern United States, Mucroseius Californicus from Monochamus clamator (LeConte) in California, and Mucroseius mexicanus from Monochamus rubigineus (Bates) in Mexico. Mucroseius aciculatus (Ishikawa, 1968), new combination, from Mecynippus pubicornis Bates in Japan, and the type-species, Mucroseius monochami Lindquist, 1962, from several species of Monochamus widely distributed in North America, are redescribed. Misidentifications of these species in the Japanese and North American literature are noted, and a key is given for these eight species. One adult female of an undescribed species found on a sawyer, Monochamus sutor Linnaeus, from Europe, is noted as possibly belonging to Mucroseius.

The taxon Mucroseius is redescribed, and its problematic status as a genus is reviewed. The phylogenetic position of Mucroseius, which appears to be derived within the genus Proctolaelaps, is discussed. Previous observations on biological and ecological aspects of Mucroseius mites, including those published in Japanese, are critically reviewed, with new data added for host ranges and specificities, distribution, phoretic behavior, occurrence in sawyer gallery systems, mode of reproduction, and their association with the pine wood nematode, Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle. Cheliceral structure and speculations on the feeding habits of these mites are discussed; however, feeding preferences have not been clarified.

The pea aphid, Acyrthosiphon pisum (Harris), is an important pest of alfalfa, Medicago sativa L., in Wisconsin because of its characteristic potential for exponential population growth (Hutchison and Hogg 1984, 1985) and the subsequent damage in both hay quality and quantity inflicted by high populations (Cuperus et al. 1982). In Wisconsin, as in most alfalfa-producing states, there is a vast complex of natural enemies (Hutchison and Hogg 1985) that influence pea aphid population dynamics, including the hymenopteran primary parasitoids from the Aphidiidae. These primary species, however, are also attacked by several secondary parasitoids from the families Megaspilidae, Pteromalidae, and Alloxystidae.

The alfalfa leafcutting bee, Megachile rotundata (Fab.), is an important domesticated pollinator of alfalfa grown for seed in Canada. Chalkbrood, a disease caused by the fungus Ascosphaera aggregata Skou, has caused high mortalities in M. rotundata populations in the northwestern United States since 1972. Chalkbrood was found in Manitoba in 1982, Alberta in 1983, and Saskatchewan in 1984 (Richards 1985). Although subsequent surveys have indicated the presence of A. aggregata at high levels in some southern Alberta M. rotundata populations, the disease has been detected only sporadically and at low levels in Saskatchewan populations (Goerzen 1990).

The forest tent caterpillar, Malacosoma disstria Hiibner, is widely distributed throughout North America and is subject to a variety of naturally occurring infectious diseases, including a nuclear polyhedrosis virus (NPV). NPVs have been isolated from several Malacosoma species in North America and Europe, including M. disstria, M. neustria, M. americanum, M. fragile, M. alpicola, M. californicum, M. pluviale, and M. constrictum (Stairs 1964). The viruses isolated from all North American species of Malacosoma may be cross transmitted from one species to another (Clark 1958). Distinctive isolates of NPV have been characterized from populations of M. disstria in Alberta (Keddie and Erlandson 1995) and Ontario (Ebling and Kaupp 1995).

(1) Crude extracts prepared from the silk glands of the silkworm, Bombyx mori L. contain trehalase activity. (2) Trehalase in the silk glands has a pH of 5.5 and a Km of 0.71 mM. The activity of the enzyme is inhibited by divalent cations such as Mn, Cu, and Zn. (3) By histochemical methods, it is shown that trehalase is localized in the periphery of the silk gland cells, especially in the tunica propria and tunica intima. (4) Trehalase activity is low in fifth instar and increases greatly in spinning stages, after which the activity decreases.

Sterility induced by gamma irradiation of the adult male tobacco budworm, Heliothis virescens (F.), was studied in two colonies, one was reared in the laboratory for more than 60 generations (laboratory strain) and the other reared for fewer than 9 generations (wild strain). When irradiated males were crossed with untreated females, the percentage egg hatch for each dose was lower with the laboratory than with the wild strain. When laboratory and wild females were crossed reciprocally with irradiated males, the fertilities were similar to those of the laboratory and wild strains, respectively. When irradiated males were crossed with female progeny from reciprocal crosses, the percentage egg hatch was similar to that of the wild strain.Wild strain females were nearly monogamous for the first several generations, but F0 females mated nearly as frequently as females of the laboratory strain.

Oviposition and fecundity of Cteniecra destructor (Brown) were studied in the laboratory and field. In a series of tests, total oviposition by individual field-collected females ranged from 495 to 1464 and averaged from 264.0 to 940.0 eggs per female. Temperatures from 50 to 86° F. had no effect on total fecundity but lower temperatures extended the oviposition period. Soil moisture from 8 to 20% in sifted clay loam soil (particle sine less than 0.177 mm.) had no effect on total oviposition. At 4% soil moisture females died rapidly and laid very few eggs. Food increased the total oviposition, the length of the oviposition period, and the longevity of females. Most eggs were laid during the first month after the onset of oviposition.

Oviposition was shown to be cyclic in nature. Females usually laid eggs in large batches, followed by periods when practically no eggs were laid. This resulted in a series of irregular oviposition peaks which gradually declined in magnitude as the oviposition period progressed.

Glossina palpalis palpalis (Robineau-Desvoidy) and Glossina palpalis gambiensis Vanderplank hybridized readily in the laboratory but hybridized females produced fewer offspring than did females that mated with their own kind. Most hybrid females were fertile when backcrossed to either G. p. palpalis or G. p. gambiensis but almost all hybrid males were sterile. About half of the backcross males were able to fertilize G. p. palpalis and G. p. gambiensis. By using an X chromosome marker gene, tan, evidence was obtained that the X chromosome is involved in hybrid male sterility, either through interaction with the Y chromosome or the autosomes of the other subspecies. There was no evidence for maternally inherited sterility factors of a type that confer unidirectional sterility on hybrid or backcross males.

Callibaetis ferrugineus (Walsh) and C. fluctuons (Walsh) nymphs moved from the shallow, peripheral area of a pond during the late summer and autumn to the deeper water where they overwintered. In the spring they returned to the peripheral area where they were found throughout the summer. C. ferrugineus and C. fluctuans are ovoviviparous. A relationship between ovoviviparity and seasonal movements of the nymphs is suggested.