We tested that hypothesis that slow re-warming rates would improve the ability of Drosophila melanogaster Meigen larvae to survive acute low temperature exposure. Four larval stages (1(st), 2(nd), 3(rd) instars and wandering stage 3(rd) instars) of four wild-type strains were exposed to -7 degrees C for periods of time expected to result in 90 % mortality. Larvae were then either directly transferred to their rearing temperature (21 degrees C), or returned to this temperature in a stepwise fashion (pausing at 0 and 15 degrees C) or by slow warming at 1 or 0.1 degrees C/min. We observed a reduced rapid cold-hardening effect and no general increase in survival of acute chilling in larvae re-warmed in a stepwise or slow fashion, and hypothesise that slow re-warming may result in accumulation of further chill injuries.
The western tussock moth, Orgyia vetusta Boisduval (Lepidoptera: Lymantriidae), formerly known as Hemerocampa vetusta (Boisduval), occurs primarily in coastal areas of central California and south into Mexico, with occasional records east of the central Sacramento and San Joaquin valleys (Ferguson 1978). Two biotypes, feeding on perennial yellow bush lupine, Lupinus arboreus Sims (Fabaceae), or silver dune lupine, Lupinus chamissonis Eschsch. (this study), and on California live oak, Quercus agrifolia Née (Fagaceae), respectively, have been recognized and were originally considered two separate species (Edwards 1881; Ferguson 1978). Various fruit and nut trees have also been reported as host plants (Atkins 1958)
The sex pheromones of Archips argyrospilus (Walker) and Archips rosanus (L.) were field evaluated to determine if they could be used to monitor populations in orchards where pest management programs were applied. Traps baited with the sex pheromones of A. argyrospilus caught males which reflected population levels estimated by other sample methods. Traps baited with the sex pheromones of A. rosanus caught high numbers of males but the numbers did not correlate with other population estimates. A. rosanus has a wide host range, and trap data indicate that males were attracted from sources outside the monitored orchards. Results indicated that the sex pheromones of A. argyrospilus could be used to estimate populations but with A. rosanus further studies on trap placement are necessary to minimize male influx.
Laboratory experiments indicate a diet of quaking aspen is essential to give impetus to a population increase of the large aspen tortrix. The effects of starvation and of five different host plants on larval survival, pupal weights, and adult egg potential are reported.
Surveys for signs of attack by Asian long-horned beetle, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), currently rely upon visual examination of trees. 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 2.5 m), and position (bole or branch) when foliage was present or absent on inspectors' 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 2.5 m, and when oviposition pits were located on boles and exit holes on branches. These main findings require some caveats, owing to a number of significant interactions. The presence or absence of foliage 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.
The efficacy of Bacillus thuringiensis was evaluated against the large aspen tortrix on trembling aspen in Alaska. A concentration of 4 × 109 IU per 378.5 L of water was applied to infested trees using a hydraulic sprayer. Treatments with Dipel 4L and Thuricide 32LV resulted in population reductions of 69 and 76% respectively. Both products provided significant foliage protection. Timing of treatment is critical to successful population suppression and foliage protection.
The life history and the immature stages, especially the ultimate larval instar, of Enargia decolor (Walker), are described and illustrated. This insect has only one generation a year in northern Alberta. It overwinters in the egg stage. The first two larval instars roll leaves and feed on the mesophyll. The last four larval instars feed on the edge of the leaves, and construct flat cases by webbing two leaves together. Pupation occurs in the soil during July. Adults emerge from late July until late August; the eggs are laid in August. Fifteen species of parasites and one species of hyperparasite were reared from larvae of E. decolor. Five of the parasites are known to have issued from other lepidopterous species feeding on aspen.
Arthropods associated with Populus coarse woody material (CWM) were sampled from aspen-mixedwood stands in north-central Alberta using rearings from wood bolts and flight-intercept traps attached to snags. More than 39 000 arthropod specimens were collected over 3 years, comprised mainly of Coleoptera, Diptera, Hymenoptera, and Acari. Detailed analyses are provided to compare the number of species, standardized abundance, and trophic structure between collecting methods for 257 saproxylic species of Coleoptera. Abundance of beetle species, from both rearings and window traps, and rarefaction estimates of species richness indicate little difference between methods with respect to expected number of species. However the abundance of particular beetle families differed significantly between methods, with the Aderidae, Anthicidae, and Scaphidiidae collected mainly in rearings and the Micropeplidae, Bostrichidae, Cephaloidae, Clambidae, Salpingidae, and Tenebrionidae more commonly collected with window traps. Fungivorous and predatory beetles were more abundant in CWM than wood borers, scavengers, or taxa with undetermined feeding habits, but the two methods revealed similar overall trophic structure. To census the variability in saproxylic arthropod faunas from CWM, a combination of collecting methods is recommended.
Females of Alydus eurinus (Say) release an attractant pheromone from their metathoracic scent gland. Conspecific males and, to a lesser extent, females and nymphs were attracted to blends containing the female-specific essential pheromone components 2-methylbutyl butyrate and (E)-2-methyl-2-butenyl butyrate, whereas individuals of Alydus pilosulus Herrick-Schaeffer were not attracted. When attacked, however, alydid adults emit chemicals for defense—butyric and hexanoic acids in A. eurinus—from the metathoracic scent glands. Mimicry is actually the first line of defense for most broad-headed bugs, including the common North American species studied here, whose nymphs are remarkable ant mimics and whose adults strongly resemble spider wasps (Hymenoptera: Pompilidae). The possibility that disparate heteropterans (Hemiptera) produce sexual pheromones in their metathoracic scent glands must be considered in future pheromone research on heteropterans, especially for species with the specialized lines of defense indicated by aposematism or mimicry.
An increment borer (5 mm core diam.) was adapted for collecting recently attacking ambrosia beetles,
LeC., in trembling aspen,
Michx. Although increment borers have been used to collect stem nematodes and stem fungi (Cordell and Stombaugh 1966), this appears to be the first use for insect collection. Previously, ambrosia beetles were collected using a hatchet and knife which was tedious and injured many specimens.
Siricids and their parasitoids were reared from Scots pine (Pinus sylvestris L. (Pinaceae)) trees infested by Sirex noctilio F. in central New York State. Sirex noctilio accounted for 94.3% of the siricid specimens emerging, totaling 1313 specimens from six trees, with a maximum of 495 from one tree. Of the individuals emerging per tree, 20.6 ± 5.2% were female. Two native siricids, Sirex nigricornis F. and S. edwardsii Brullé, also emerged from trees but in low numbers. Three hymenopteran parasitoid species that attack siricids emerged, totaling 21.8 ± 6.4% parasitism per tree. Ibalia leucospoides ensiger Norton (Ibaliidae) was by far the most abundant parasitoid, at 20.5 ± 6.3% parasitism per tree. The percentage of female S. noctilio emerging was positively correlated with wood diameter, whereas percent parasitism by I. l. ensiger was negatively correlated with wood diameter.
A revision is presented of the species of Graphomya Robineau-Desvoidy found in North America. Nine species are recognized of which two, G . americana R.-D. and G . idessa Walker, are resurrected from synonymy under G . maculata (Scopoli), and the others, G . occidentalis , G . interior , G . columbiana , G . minuta , G . ungava , G . alaskensis , and G . transitionis , are described as new.
A review of the taxonomic position and biological information of the genus Graphomya is presented. Keys are provided for both males and females of the species from North America. Each species is described and biological information, when known, is presented. Distribution for each species is presented by locality records and a distribution map. A generic diagnosis for Graphomya from North America is also given.
The genus Anoplonyx Marlatt belongs to the more generalized of the Nematinae and is clearly defined taxonomically by Ross (1937). This genus is comprised of very few known species, four in North America and four in Europe; all are associated with trees of the genus Larix . The species are similar in appearance and difficult to distinguish, especially in the adult stage.
Considerable confusion existed concerning the identification of the members of this genus in North America up until Wong (1955) published a key to separate the late feeding stages of Anoplonyx larvae found in Canada. The two species dealt with herein are apparently native to Eastern Canada and have generally been identified as one species, “Marlatt's Larch Sawfly”, A. laricis (Marlatt). Here they are identified as A. luteipes (Cresson) (= laricis Marlatt), and A. canadensis Harrington, as listed bv Ross (1951).
In a trapping study conducted in the experimental research forest of the Tohoku Research Center, Morioka, Honshu, Japan, we investigated the effect of heterospecific pheromone on pheromonal attraction of male Japanese gypsy moth, Lymantria dispar japonica (Motschulsky), and male pink gypsy moth, L. mathura Moore (Lepidoptera: Noctuidae: Lymantriinae). Traps baited with synthetic pheromone of L. d. japonica ((7R,8S)-cis-7,8-epoxy-2-methyloctadecane = (+)-disparlure (100 μg)) or L. mathura ((9R,10S,3Z,6Z)-cis-9,10-epoxynonadecadiene = (+)-mathuralure (20 μg) and (9S,10R,3Z,6Z)-cis-9,10-epoxynonadecadiene = (-)-mathuralure (80 μg)) attracted male L. d. japonica or L. mathura, respectively. Traps baited with synthetic pheromone of both species captured significantly fewer male L. mathura than traps baited solely with synthetic L. mathura pheromone. Numbers of male L. d. japonica captured in traps baited with (+)-disparlure were unaffected by the addition of L. mathura pheromone. (+)-Disparlure is a behavioral antagonist to pheromonal attraction of male L. mathura, whereas male L. d. japonica are indifferent to the presence of synthetic L. mathura pheromone.
In pheromone-based surveys for detecting multiple species of exotic lymantriine moths (Lepidoptera: Noctuidae: Lymantriinae), spacing between traps baited with species-specific pheromone lures must be sufficient to prevent antagonistic effects of heterospecific pheromone on lure attractiveness. Conducting field experiments with the Japanese gypsy moth, Lymantria dispar japonica Motschulsky, in northern Honshu, Japan, we first determined which congeneric pheromone components have strong antagonistic effects on attraction of male moths to the conspecific pheromone (7R,8S)-cis-7,8-epoxy-2-methyloctadecane ((+)-disparlure). Since the most antagonistic compounds were pheromone/volatile components from the sympatric nun moth, L. monacha (L.), we then conducted experiments with paired traps baited with either a L. dispar (L.) pheromone lure ((+)-disparlure (50 μg)) or L. monacha pheromone lure (a mixture of (7R,8S)-cis-7,8-epoxyoctadecane ((+)-monachalure (50 μg)), (7Z)-2-methyloctadecene (5 μg), and (+)-disparlure (50 μg)). As spacing between paired traps increased (0, 0.5, 2, 7.5, 15, or 30 m), the antagonistic effect of the L. monacha lure on the attractiveness of the L. dispar lure decreased and finally disappeared. For pheromone-based detection surveys of multiple species of exotic lymantriine moths in North America to be effective, trap spacing of 15 m is recommended.
During field studies of the behaviour of larvae in colonies of Malacosoma disstria Hbn., it was observed that two species of ants, Camponotus herculeanus ligniperdus (Latr.) and Formica fusca L., were common on the twigs of the small trees, Populus tremuloides Michx., on which the caterpillars were established. Ant nests were common near the bases of trees, and the worker ants climbed the trunks and moved along the branches either to forage or to tend aphid colonies. When the tent caterpillars were small, they were frequently attacked by the ants. There were two distinct types of attack: one the result of foraging by worker ants and the other the result of defence of aphid colonies by the ants.
A pictorial representation of the gut of the green peach aphid,
(Sulzer), is shown based on dissection, light microscopy, and electron microscopy.
The sucking pump is crescentic in cross section with a thick, rigid, posterior wall and a thinner, flexible, anterior wall. Dilator muscles arise on the clypeus and are inserted along the midline of the anterior wall of the pump chamber. Morphologicael evidence of the sucking action of the pump is included.
The serological relationships of Pissodes strobi (Peck) and P. approximatus Hopkins were examined using turbidimetric and immunodiffusion analyses. Hylobius pales Hbst. was used for heterologous comparisons. When turbidimetric analyses were performed using anti-strobi sera, heterologous reactions with P. approximatus were stronger than homologous reactions. Moreover, immunodiffusion tests substantiated this. These results appear to have broken a cardinal rule of serology: that hererologous reactions do not exceed homologous reactions in magnitude.These results could he due to a simple quantitative variation in the antigen extracts or to possible cross-reactivity between antigenically similar proteins. Another possibility is that the two populations are not separate species. Evidence obtained in this study seems to be in accord with cytological evidence obtained hi previous studies and does not support the designation of P. approximatus as a valid species.
Adult Asian long-horned beetles, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae: Lamiinae), were discovered in Ontario, Canada, in 2003 in the vicinity of a commercial warehouse. Trees were heavily scarred with signs of attack and larvae and adult beetles were common, suggesting that there had been multiple generations at the site. We amplified 16 microsatellite loci from 326 beetles to examine genetic diversity in this population. Based on Hardy – Weinberg equilibrium, 6 of 16 loci were monomorphic and 8 were not, indicating nonrandom mating. Measures of microsatellite genetic diversity and mitochondrial DNA haplotype diversity were significantly lower than those in A. glabripennis from China and Korea but were not significantly different from those in the New York City population. The proportion of different multilocus genotypes in the Ontario population was lower than in the populations in New York City and Linden, New Jersey. These results suggest that limited genetic diversity in the Ontario population has not hampered reproduction of this invasive insect. This genetic signature is common in other invasive species, likely because a population is founded by a few closely related individuals, or a large founding population suffers subsequent genetic bottlenecks.
Periodic outbreaks of the large aspen tortrix, Choristoneura conflictana (Wlkr.) severely defoliate trembling aspen, Populus tremuloides Michx., in parts of Manitoba and Saskatchewan. The inadequacy of information on the insect prompted further investigation of its life history and the factors affecting its abundance. Field studies were conducted in Northern Manitoba and Saskatchewan, where from 1950 to 1954 the insect was found at various population levels.
Mating, oviposition, and flight in the satin moth, Leucoma salicis (L.), were studied in an aspen forest in Maine during 1975 and 1976. Adult eclosion normally occurred between 0800 h (EST) and 2300 h, with males emerging earlier both daily and seasonally. Female calling behavior and mating occurred shortly after sunset on the day of eclosion. Mating lasted ca. 19 h, terminating prior to sunset; low temperatures extended the period of mating. Multiple mating was observed in males and females. Oviposition normally occurred between 1600 and 2330 h. The largest egg masses were the first laid, with sequentially smaller masses laid on following days. Confined females laid an average of 4.6 egg masses containing a total of 650 eggs. Female flight normally followed oviposition of the first egg mass; thereafter, the period of daily flight often preceded oviposition. Male flight started at 0500 h, peaked between 1600 and 2100 h, and ended at 0130 h. Adult longevity under confined field conditions averaged 8.6 days for males and 9.4 days for females.
The aspen blotch miner, Lithocolletis salicifoliella , Cham., has been abundant on trembling aspen, Populus tremuloides Michx., throughout central Canada for the past few years. The mines of this species are found on the underside of the leaves, and are often abundant enough to cause premature browning of the foliage. This insect first came to the attention of the Forest Insect Survey of Ontario in the vicinity of Lake Nipigon in 1944. By 1950, the infestation covered all but the southern part of Ontario, and was reported in most aspen stands in Manitoba and Saskatchewan. The intensity of the infestation in the northern part of Ontario began to decline by 1952, and in 1954 damage was negligible.
A previously undescribed entomopoxvirus was isolated from larvae of Choristoneura conflictana Wlk. Samples of larvae taken from several points in Ontario indicated that the virus was widespread in the Province.
The morphology of the virus is described. The inclusion bodies are larger than those of another entomopoxvirus originally isolated from Choristoneura biennis Free. and propogated in Choristoneura fumiferana (Clem.). The virions are of the same order of size for both viruses. Microspindles are associated with these viruses and some of the spindles are occluded along with the virions within the oval inclusion bodies. The C . conflictana entomopoxvirus is also infectious to C . fumiferana .
Stands of trembling aspen in Manitoba and Saskatchewan are frequently attacked by the forest tent caterpillar, Malacosoma disstria Hbn. The recent history of attack is reviewed in this paper to determine if there is evidence of a consistent pattern of outbreaks and if the latest of these had any appreciable effect on aspen stands in the two provinces.
The large aspen tortrix, Choristoneura conflictana Wlk., occurs throughout the range of trembling aspen, Populus trernuloides Michx., in Canada and the eastern United States (Baker 1972). Outbreaks of the insect occur over large areas, but these outbreaks generally collapse in 2 to 3 years. The principal effect of this pest is to reduce growth of aspen, but it causes little tree mortality (Batzer 1972). Prentice (1955) reviewed the history of outbreaks of C. conflictana in Canada from 1912 to 1953 and the natural control factors of the insect. He reported an extensive parasite complement. Dead and apparently diseased insects were examined, but the only pathogen noted was infection of overwintering larvae by the fungus, Beauveria bassiana (Bals .) Vuill.
The aspen leaf miner, Phyllocnistis populiella Cham., has recently become common and very abundant in western North America, and has been authoritatively identified only from trembling aspen, Populus tremuloides Michx. Overwintered adults lay eggs on young aspen leaves in spring, and new-generation moths emerge in about two months. Only the single epidermal cell layer is mined on the upper or lower leaf surface, most of the feeding being done by the third-instar larva in about a week. Heavy attack results in defoliation by mid-summer. Activities of breeding populations are affected by temperature (50-55°F. is optimal for copulation, 54-56°F. for feeding, and 52-58°F. for oviposirion) and developmental stage of aspen leaves. Eggs are laid singly near the apex of the leaf and tend to be evenly spaced. Distribution of eggs between leaves tends to be uniform in a particular level of the tree, although more eggs are laid in the lower crown. A female moth can develop more than 40 eggs, but only about 7 are usually laid because of limited opportunities. Mortality in the larval and pupal stages is often high; population decline usually follows mortalities above 70%. Parasitism sometimes plays an important role, but the independence of population changes between broad geographic areas suggests that numbers of P. populiella may be strongly influenced by climatic factors. Population trends and damage can be assessed conveniently for large geographic areas and for specific sites by continuing studies in permanent sample plots. Expected damage may be predicted from estimates of new-generation adult populations. Because inter-tree variation exceeds intra-tree variation, more trees and fewer branches per tree should be taken to increase sampling efficiency. Also, greater precision is attained by the use of the individual leaf surface rather than the leaf as a basic sample unit.
Moths of the genus Pseudexentera are early-season fliers that include three species of economic importance: P. spoliana (Clemens) on oak (Quercus), P. oregonana (Walsingham) on aspen (Populus), and P. mali Freeman on apple (Malus). GC and GC/MS analysis, EAG and behavioral bioassays, and field tests confirmed that Z10-16:Ac is an attractive sex pheromone component of female P. spoliana. Capillary GC analysis supported by GC/MS also indicated the presence of 16:Ac, Z10-16:OH, and 16:OH in pheromone extracts and there was tentative GC evidence for Z12-16:Ac. However, addition of these compounds to Z10-16:Ac in various blends did not enhance male attraction. The major sex pheromone component of female P. oregonana is Z8-14:Ac. There was also GC and GC/MS evidence for Z8-14:OH and tentative GC evidence for 14:Ac in the pheromone of this species. Their addition to Z8-14:Ac failed to increase moth catches in baited traps. Pseudexentera mali males were attracted by Z,Z-8,10-16:Ac, a previously reported sex pheromone of this species. Pheromone lures targeted for each species were not cross-attractive.
Monitoring of pear psylla (Cacopsylla pyricola (Forster), Hemiptera: Psyllidae) prior to spring bud break could aid in predicting the size of subsequent spring populations and lead to improved proactive management decisions. Yellow traps are commonly used to monitor hemipteran pests including pear psylla, but very little is known regarding seasonal changes in attractiveness of yellow traps or relative attractiveness of colours other than yellow. This study presents seasonal colour-trap preferences of pear psyllas based on pear (Pyrus communis L., Rosaceae) phenological stages in the mid-Atlantic region of the United States of America. Black, blue, brown, clear (colourless), green, orange, red, white, and yellow traps were assayed against wild adult psylla populations over a 2-year period. Pear psyllas had a strong preference for yellow and orange when green leaves were present; however, we found no statistically significant difference between traps of different colours prior to spring bud break. Significantly more female psyllas were caught overall, but there was no gender-based colour bias. None of our colour traps caught significantly fewer psyllas than did clear (background hue) traps, suggesting that no traps were repellent.
During the summer of 1982, aerial experimental sprayings were carried out with a new formula of Bacillus thuringiensis named Futura®. This formula provided a treatment of the 20 × 109 IU of B. thuringiensis/ha required for suppression of spruce budworm (Choristoneura fumiferana), in a final volume of 2.5 L/ha. Results of spraying with Grumman AgCat and DC-4G aircraft are presented. These results were compared with those obtained with formulas of B. thuringiensis used in the past at 4.7 L/ha. Futura® caused 91.1 and 88.7% larval mortality and resulted in 86.6 and 75.1% foliage protection with the Grumman AgCat and DC-4G aircraft, respectively. Such results were equal to or better than those obtained with the formulas used earlier at 4.7 L/ha and confirm the feasibility of using B. thuringiensis operationally in an efficient and economical way.
A sequential egg-band sampling system for predicting defoliation of aspen by the forest tent caterpillar (Malacosoma disstria Hbn.) is described and its accuracy assessed. A probability method of predicting defoliation from the stage of the outbreak in each local area is also established. A third method, which promises to be the most accurate and consistent, is proposed. In this last system, egg-mass density is established and related to defoliation levels which are adjusted depending upon age of outbreak.
We studied the abundance, diversity, and dispersion patterns of managed and wild bee (Hymenoptera: Apoidea) populations in commercial highbush blueberry and cranberry (Ericaceae: Vaccinium corymbosum L., Vaccinium macrocarpon Ait.) fields in the Fraser Valley of British Columbia, and assessed their potential as pollinators of these crops by determining which groups of bees had the greatest impact on percent yield and mass of berries. Bumble bees were evenly distributed within both crops. Other wild bee species were well distributed in blueberry fields but generally remained at edges of cranberry fields. Percent berry yield was not related to bee abundance for any group of bees, nor was species diversity correlated with berry mass. Blueberry mass and cranberry mass were related to abundance of bumble bees but not to that of honey bees or other wild bees. Bumble bees are recommended as potential alternative pollinators of these crops.
The spruce beetle has possible life cycles of 1 or 2 years. Empirical and experimental evidence suggest that temperature is the primary regulator of these life-history pathways. These different life cycles potentially result in substantial differences in population dynamics and subsequent spruce mortality. A multi year field study was conducted in Utah, Colorado, and Alaska, to monitor spruce beetle development under a variety of field conditions with concurrent air temperature measurements. This information was used to model the tree- or stand- level proportion of univoltine beetle as a function of air temperature. Temperatures were summarized as averages, cumulative time, and accumulated heat units above specified thresholds over various seasonal intervals. Sampled proportions of univoltine insects were regressed against the summarized temperature values in logistic models. The best predictive variable, as evaluated by Akaike's Information Criterion, was found to be cumulative hours above the threshold of 17 degrees Celsius elapsed from 40 to 90 days following peak adult funnel-trap captures. Because the model can be used to forecast trends in spruce beetle populations and associated spruce mortality, it is a tool for forest planning.
Temperature-dependent development of the egg, larval, and pupal life-stages of the mountain pine beetle (Dendroctonus ponderosae Hopkins) was described using data from constant-temperature laboratory experiments. A phenology model describing the effect of temperature on the temporal distribution of the life-stages was developed using these data. Phloem temperatures recorded in a beetle-infested lodgepole pine (Pinus contorta Douglas) were used as input to run the model. Results from model simulations suggest that inherent temperature thresholds in each life-stage help to synchronize population dynamics with seasonal climatic changes. This basic phenological information and the developed model will facilitate both research and management endeavors aimed at reducing losses in lodgepole pine stands caused by mountain pine beetle infestations.
Beginning 1 year after an intense forest fire in the Interlace region of Manitoba, carabid beetles were sampled by pitfall trapping in two burned sites and two unburned control sites. Before the tire, one burned site had been dominated by aspen, Populus tremuloides Michx,, and the other by conifers (mostly Picea spp.). During the 11-year study, burned sites became dominated by aspen saplings. Three carabid species were caught significantly more frequently in burned sites than in control sites. Two of these, Harpalus laticeps LeConte and H. egregius Casey, invaded soon after the fire and were caught in the burned sites for several years after the fire. Seventeen species were caught significantly less often in burned than in control sites; catches of another 13 common species were not significantly affected by burning of the site. Burning influenced the seasonal patterns of catches of Carabus taedatus F. and Pterostichus adstrictus Eschscholtz; this was attributed to higher litter and soil temperatures in burned sites. Seasonal patterns of other common species were not markedly affected by burning. In burned sites, the incidence of brachypterous species and the size of beetles increased with time after the fire. In control sites, the incidence of brachyptery was independent of time, but the percentage of brachypterous species was significantly higher in the conifer site than in the aspen site. Trends of brachyptery and size are those expected if early colonizers are super-tramp r-strategists and later invaders are K-strategists. Patterns of species occurrence during forest regeneration can be explained in terms of dispersal and competitive abilities, preference for physical attributes of the habitat, and responses to prey availability.
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.
First-stage forest tent caterpillar larvae were tested for the presence of active and sluggish behavior types such as Wellington found in Malacosoma californicum pluviale (Dyar). Larvae capable of directed movement towards a 30 w light source were classified as active. Larvae were tested on 3 consecutive days, and only a small percentage responded on all 3 days. A much larger percentage remained sluggish throughout the period. Chi-square tests confirmed that the differences in response were not random. There was a tendency for some larvae to respond to light during the test and for others not to respond. The reduced consistency in the response of "active" larvae in M. disstria Hübner compared with that reported for M.c. pluviale may be partly due to real behavioral differences, but it also may be partly due to some procedural differences between our tests and Wellington’s.
Fitness, defined as the per capita rate of increase of a genotype with reference to the population carrying the associated genes, is a concept used by biologists to describe how well an individual performs in a population. Fitness: is rarely measured directly and biologists resort to proxies more easily measured but with varying connection to fitness. Size, progeny survival, and developmental rate are the most common proxies used in the literature to describe parasitoid fitness. The importance of the proxies varies between papers looking at evolutionary theories and those assessing ecological applications. The most direct measures of fitness for parasitoids are realised fecundity for females and mating ability for males, although these proxies are more difficult to measure under natural conditions. For practical purposes, measure of size, through body size or mass, is the proxy easiest to use while providing good comparative values; however, care must be taken when using a single proxy, as proxies can be affected differently by rearing conditions of the parasitoid. [KEYWORDS: LARVAL COMPETITION; QUALITY-CONTROL; CLUTCH SIZE; HOST; HYMENOPTERA; FIELD; SELECTION; WASP; SUPERPARASITISM; ICHNEUMONIDAE]
Sweetman (1940) suggested that unfavourable spring weather is probably the most important natural check for the forest tent caterpillar, Malacosonza disstria Hbn. He observed that warm weather in April or early May that induces hatching, followed by a week or more of cool weather, frequently destroys the caterpillars. Blackman (1918), Tomlinson (1938), and Hodson (1941) have reported similar observations.
Heinrich is highly destructive to cones and seed of western white pine,
Douglas, and is distributed throughout the geographic range of this host species in northern Idaho. One generation is passed per year with emergence in late May. Egg and larval stages arc generally found in June and July; the pupal stage overwinters. Stand density and elevation were used as variables in ecological studies of population sine. All stages of
were correlated to phenological data in 1962.
The life history of Chrysomela crotchi , a univoltine species commonly found on trembling aspen, was studied in northwestern Ontario from 1959 to 1962. The most striking feature of its life history was the longevity of adults, which were capable of overwintering two successive years. Overwintered adults became active and began feeding in late May, and oviposition occurred from early June to late July. The incubation period was approximately 10 days and the three larval instars required approximately one month for development to the adult stage.
Females laid more eggs during their second season and the highest number laid was 326. The number of eggs in an egg mass averaged 37.6, and the average interval between the deposition of egg masses was 4 days. Males and females mated more than once, but only one mating was necessary for a female to produce viable eggs throughout the season. Males were capable of fertilizing more than one female and remained potent for more than one season.
Parasitism was low, and only two species of larval parasites were reared. Several predator species were observed preying on the immature stages. Predation and overwintering mortality appeared to be the most important control factors.
A polyhedrosis virus was found in collections of Bruce spanworm, Operophtera bruceata (Hulst), larvae from two locations in British Columbia in 1957 (O. N. Morris, pers. comm.). Bruce spanworm was prevalent in the Maritime Provinces and Quebec in 1963 and 1964 and a polyhedrosis virus was credited with terminating this outbreak (Forbes et al. 1964, 1965; Martineau 1964, 1965). A detailed examination of the virus from Quebec showed that it was a singly-embedded (unicapsid) nuclear polyhedrosis virus (Smirnoff 1964) which is classified as Baculovirus subgroup A (Matthews 1979).
For the last 50 years, populations of the Bruce spanworm, Operophtera bruceata Hulst, and other wingless geometrid species have been sampled using sticky bands placed around host-tree trunks to catch wingless females in search of oviposition sites. This method is tedious and, because of trap saturation by males, may underestimate female populations at moderate to high levels. A standard oviposition trap was developed to sample eggs of the Bruce spanworm and other wingless geometrid species. A small polyurethane foam band placed on a post covered by a Multi-Pher® plate detected low populations and was almost unsaturable during outbreaks. Sub-sampling can be easily done in such situations. Egg density on oviposition traps was higher than female density on sticky bands for both the Bruce spanworm and the fall cankerworm, Alsophila pometaria Harris. This suggests that the oviposition trap might be useful to sample other wingless geometrid species. Operating this system was easy and could involve woodlot owners and companies to reduce the traveling costs necessary to collect samples.
Neodiprion sawflies are economic pests in pine plantations in eastern and southern United States and eastern Canada. While not a serious problem in California at the present time, they will probably become so with the advent of more intensive forest management.
Little is known of the species present in California. The only specific study was that concerned with the Neodiprion abietis complex on white fir in 1952 (Struble, 1957). Miscellaneous data are available from the survey records of the Pacific Southwest Forest and Range Experiment Station, Berkeley.
Larval growth and pupal parameters of the forest tent caterpillar (Malacosoma disstria Hübner) reared on the foliage of two host trees (Populus tremuloides Michx. and Acer saccharum Marsh.) and one nonhost tree (Acer rubrum L.) were quantified. This was achieved by undertaking a larval development bioassay under controlled laboratory conditions, but using fresh leaves collected in two field seasons. Larvae fed foliage of P. tremuloides grew exponentially and began to pupate after 3 weeks. Larvae fed with A. saccharum gained significantly less weight and had a reduced number of larvae pupate, and the pupae weighed significantly less than their counterparts fed on P. tremuloides. All larvae that were fed the foliage of A. rubrum died within 2 weeks. A nutritional utilization bioassay with fourth-instar larvae revealed that the foliage of A. saccharum has a growth-inhibitory component, whereas that of A. rubrum is antifeedant. Reasons are discussed for the discrepancy between the many reports of A. saccharum being a food host for M. disstria in the field and the laboratory results.
Dimilin (25% wettable powder) was mixed in water and sprayed from a Grumman Agcat aircraft equipped with four micronair units at the rate of 70 g (active ingredients) / 4,67 L/ha (1 oz/0.5 U.S. gal per acre) on two stands of trembling aspen, Populus tremuloides Michx., heavily infested with forest tent caterpillar, Malacosoma disstria Hübner. The material was applied when the insects were in the first and second instars and the trees were starting to flush. Spray deposit analysis using a dye, Rhodamine-B, in the spray mix and spray plates in the plots indicated that conditions for spraying in the morning were better than those in the evening as expected. Total control of the forest tent caterpillar with very little defoliation of the trees was achieved.
An outbreak of the forest tent caterpillar began in northern Minnesota in 1964 and ended abruptly in 1972. During 1968–71 when egg densities ranged from 1 to 9 million per acre, caterpillars caused virtually complete tree defoliation in all study plots. As a result, tree stem densities and basal areas were reduced per plot by 41 and 27%, respectively. Tree mortality was more severe on plots having higher water tables. Graphical and components of variance analyses both showed that: (1) variations in annual egg densities were due mostly to variations in survival during the egg to 30-day larval stage (SI) and secondly to variations in survival during the 30-day larval to adult stage (S2), (2) S2 tended to change in the opposite direction from S1, (3) the net result was a tendency to produce a constant amount of eggs per unit area. Variations in S1 were due primarily to pharate larval mortality and mortality of larvae 2–3 weeks after hatch while variations in S2 were due mainly to unmeasured mortality factors such as starvation, disease, dispersal, etc. Survival during the egg stage (SE) and fecundity (F) varied significantly by years, but not by plots and both were apparently related to weather conditions. Plots of two simultaneous equations were presented to demonstrate the nature of population change in relation to the densities of eggs and 30-day larvae per acre.
Four new species are described: Commellus cedilla from Alaska, Canada, and adjacent northeastern states; C. hyphen from the aspen parkland of Saskatchewan to North Dakota; C. semicolon from southern Montana; and Extrusanus oryssus widespread in northern prairies (Alberta to Kentucky). Alary polymorphism in both genera is discussed. Species-specific characters from enclosed male genitalic structures are described and illustrated in detail for the first time, for all species except C. hyphen. Keys are presented to the species of both genera.
The red turpentine beetle, Dendroctonus valens LeConte, 1860 (Coleoptera: Curculionidae, Scolytinae), is a common bark beetle found throughout much of North America and China. In 2004, we observed that attack densities of the California fivespined ips, Ips paraconfusus Lanier, 1970 (Coleoptera: Curculionidae, Scolytinae), in logging debris were inversely related to D. valens attacks on freshly cut stumps, which led to the demonstration that components of the aggregation pheromone of I. paraconfusus inhibited the response of D. valens to attractant-baited traps. In this study, we test the response of D. valens and Temnochila chlorodia (Mannerheim, 1843) (Coleoptera: Trogositidae), a common bark beetle predator, to racemic ipsenol, racemic ipsdienol, and (−)-cis-verbenol (IPSR) in the presence and absence of two release rates of (−)-verbenone. The addition of a relatively low release rate of (−)-verbenone (4 mg/24 h) to attractant-baited traps did not affect catch and had no significant effect on the response of D. valens to IPSR. IPSR significantly reduced D. valens attraction to baited traps. The addition of high release rates of (−)-verbenone (50 mg/24 h) to IPSR significantly increased inhibition; however, the effect was not significantly different from that observed with (−)-verbenone alone (50 mg/24 h). Temnochila chlorodia was attracted to traps baited with (−)-β-pinene, (+)-3-carene, and (+)-α-pinene. The addition of (−)-verbenone (50 mg/24 h) significantly increased attraction. Traps baited with IPSR caught significantly more T. chlorodia than those baited with (−)-verbenone. Few other beetles were collected. We are hopeful that these results will help facilitate the development of an effective tool for protecting Pinus spp. from D. valens infestations.