摘要:

Instar number inMelanoplus femurrubrum(DeGeer) is variable. Virginia populations were found to be developmentally polymorphic, having from five to eight nymphal instars. Grasshoppers with five instars were rare. In the field, fewer instars were associated with years with low May–June temperatures. Variation in instar number among populations, between years, and within seasons is due to variation in early season temperatures. A laboratory population had six to eight instars, with fewer instars occurring at lower rearing temperatures. Females went through more instars than males. Antennal segment number was correlated with instar number. Virginia populations ofM. femurrubrumare developmentally adapted to a relatively long growing season.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.120

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Field tests using sticky traps revealed that eugenol and 2-methoxy-4-propylphenol were highly attractive toDiabrotica cristata(Harris) andD. barberiSmith&Lawrence, whereas isoeugenol acetate was not attractive. None of the compounds was highly attractive toD. virgifera virgiferaLeConte but there was significant, albeit low, attraction of females to 2-methoxy-4-propylphenol.D. barberiin South Dakota responded in the same way to these compounds as it did in Ohio in earlier tests. Response to these attractants parallels host plant affinities among the species.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.126

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

A seven-stage system of gonotrophic development is described for sugarbeet root maggot,Tetanops myopaeformis(Röder), based on dissections of laboratory-reared puparia and adults. Vitellogenesis occurred in secondary and tertiary follicles before completion of primary follicle development, indicating that time between successive ovipositions in the field is short. Follicular growth is initiated in late pupal stage and rate of development is determined by temperature. Approximately 2 days at 25°C or 34 degree-days were required for newly emerged adults to mature. Four age classes were determined for describing oviposition status of adult females. Use and application of the results in pest management programs in sugar beets are discussed

ISSN:0046-225X    

DOI:10.1093/ee/16.1.129

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Field experiments were conducted in conventional-till (CT) and no-till (NT) tomatoes in both rotated and nonrotated fields to determine effects of different cultural practices on population trends of Colorado potato beetle (CPB),Leptinotarsa decemlineata(Say). CPB were more abundant in CT than in NT plots in both rotated and nonrotated tomato fields. Earlier colonization of overwintered adults in CT plots resulted in higher egg mass densities and subsequent infestation of first-generation larvae and adults. In treatments where fenvalerate was applied to control CPB populations above economic thresholds, four spray applications were required in CT plots, compared with two applications in NT. Tomato fruit yield and soil moisture content were greater in NT than in CT plots in the rotated field.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.135

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Citrus blackfly (CBF),Aleurocanthus woglumiAshby, was discovered in Fort Lauderdale, Fla., in 1976. ParasitesEncarsia opulenta(Silvestri) (Hymenoptera: Aphelinidae) andAmitus hesperidumSilvestri (Hymenoptera: Platygasteridae) were released in infested areas. CBF populations declined and control is now mainly due to the k-selected parasiteE. opulenta. On Merritt Island, however, a third parasite, now known to be a facultative hyperparasite onE. opulenta, was released:Encarsia smithi(Silvestri). Parasite and CBF populations were monitored on Merritt Island from 1981 to 1984. The three parasite species progressed through an initial dominance byA. hesperidum, to intermediate dominance byE. smithi, to final dominance byE. opulenta.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.140

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Following its invasion of eastern Ontario during the mid-1970's, numbers of the alfalfa blotch leafminer,Agromyza frontella(Rondani), increased rapidly to economic proportions and then receded to near tolerable levels. Thirty-three life tables were compiled from population and mortality data collected during this colonization phase. Analysis of the components of mortality using a variance/covariance matrix of the separate mortalities, as expressed askvalues, showed that maggot mortality within leaf mines was the key factor that determined population trends. Maggot mortality was the result of two contemporaneous processes fluctuating with a similar order of magnitude: exploitation and interference competition among instars, and predation by a complex of indigenous nabids and mirids. Although the former process was density dependent, its regulatory potential was damped by the inverse response of the predators, whose activity diminished the competitive interaction. Prepupal mortality was high but relatively invariant. Mortality from other causes was low and contributed little to population trend. Life tables for the larval stage in central Quebec resembled those for Ontario.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.145

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

An aerial water-pan pheromone trap (AWPT) was compared with 15-W blacklight (BLT) and Pherocon 1-C sticky traps (ST), for trapping the European corn borer (ECB),Ostrinia nubilalis(Hübner). At low ECB population densities, the catches in AWPT and BLT were not significantly different, whereas at higher ECB densities, catches in BLT were greater. The AWPT caught significantly more ECB, at all densities, than did the ST. Night observations revealed the AWPT to be 400% more efficient at trapping ECB than the ST. Competition by virgin females, and the sedentary tendency of males, could explain why catches were similar at low densities and dissimilar at higher densities.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.154

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Poultry manure exhibited a moisture content range of 21.0–88.2% ($\bar x$= 68.7%) and a temperature of 14.8–44.2°C ($\bar x$= 26.0°C). Third-instar house flies,Musca domesticaL., were recovered from a moisture range of 37–80%, with 85.9% found from 60 to 79% moisture. Over half ofMacrocheles muscaedomesticae(Scopoli) adults (61.8%)were found in the 50–69% moisture range, with 26.2 and 30.7% of the females and males, respectively, recovered from 70 to 79% manure moisture. Third-instar house flies, showing a wide temperature tolerance, were recovered from ca. 17 to 35°C. The mites had a similar temperature range. Few of the sampled third-instar house flies (5–7%) were found in areas of manure cone formation, but a majority of the mites (60.1–75.3%) was recovered from this type of accumulation. Dispersions of larvae and mites were independent according to a x2test for independence and Lloyd's index of interspecific patchiness (IP) for measuring spatial overlap. Mite sexes were positively associated and IP indicated a 7.71-, 3.327-, and 3.53-fold higher probability of encounter in the three quadrat sizes used in the study than would be the case if both sexes were distributed randomly in the habitat. Mean female/male sex ratios of 3.1:1, 2.4:1, and 2.8:1 forM. muscaedomesticaewere observed.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.159

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

A method for rapid field estimation of gypsy moth,Lymantria dispar(L.), fecundity was developed and validated. A log-transformed linear regression (y= 1.58x + 0.29) was used to estimate number of eggs per mass from egg-mass length over a range of 8–54 mm in length and a range in fecundity of 26–1,509 eggs per mass (r2= 0.71). The model was tested against two independent data sets and data were pooled to produce parameter estimates that are independent of insect density, year, and locale.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.165

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

The ground-dwelling beetle assemblages of seven reclaimed surface coal mines (revegetated at 1-yr intervals beginning in 1979) and an undisturbed area of sagebrush steppe vegetation near Kemmerer, Wyo., were sampled in 1983 using 25 pitfall traps per site. The three oldest sites (1977–79) received no topsoil during reclamation; the other four sites (1980–83) had stored topsoil respread on them before revegetation. The beetle assemblages were characterized by means of data on species richness and diversity, species dominance curves, and trophic-group structure. We found that initial recolonization and dominance was achieved by species that were either rare in the adjacent native vegetation, or had immigrated from other disturbed sites. Species richness and diversity showed an increase during the first 3 yr following revegetation, but then declined over the next 3 yr. The magnitude of the observed species richness and diversity trends may have been influenced by the presence or absence of topsoil on the sites. The number of herbivorous beetle species was positively correlated with the number of plant species present on the sites. The trophic structure on reclaimed mine sites was dominated by omnivores, insect-carrion feeders, predators, and fungivores, whereas the undisturbed site's beetle fauna was dominated by omnivores, predators, and herbivores. It seemed that the most successful colonists were omnivorous and scavenging species (that used seeds, weedy vegetation, and living and dead insects), and fungivores (that took advantage of fungi growing on dead organic matter in the respread topsoils). In view of the great dissimilarities that exist between undisturbed and reclaimed mine sites, even after 6 yr, we conclude that recovery of the mine lands will require a considerable length of time, and, due to the severity of the mining disturbance, may not ever yield a fauna and flora similar to those of the premining era.

ISSN:0046-225X    

DOI:10.1093/ee/16.1.168

出版商:Oxford University Press    

年代:1987

数据来源: OUP