摘要:

The frequency and intensity with which the red imported fire ant,Solenopsis invictaBuren, invaded fresh cattle droppings was studied from March to November 1982 at a study site in Burleson Co., Tex. A total of 465 droppings were collected and 307 were infested with varying numbers of fire ants. Large aggregates ofS. invictawere observed on the droppings and they appeared to discourage oviposition attempts by various fly species. Observations of cattle droppings revealed thatS. invictawas an active predator of larvae of the horn fly,Haematobia irritans(L.), and eggs and larvae ofOrthellia caesarion(Meigen).

ISSN:1754-5692    

DOI:10.1093/ee/13.5.1161

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Newly emerged adultMonochamus carolinensis(Olivier) were tested to determine if there was a host preference in feeding during the period of sexual maturation. Beetles were given a choice of bark from four pine species. Insects emerging from Scotch pine (Pinus sylvestrisL.) and jack pine (P, banksianaLamb.) consumed significantly more bark of Scotch pine. Those which emerged from short leaf pine consumed significantly more jack pine. Overall, Scotch pine was the most preferred host, while shortleaf and eastern white pines (P. echinata[Mill.] andP. strobusL.) were the least preferred.

ISSN:1754-5692    

DOI:10.1093/ee/13.5.1164

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Bollworm,Heliothis zea(Boddie), and tobacco budworm,H. virescens(F.) larvae were collected at weekly intervals from 6 April through 28 August 1981 from several species of wild and cultivated host plants in the delta of Mississippi. The species, seasonal occurrence, and abundance ofHeliothislarvae and their larval parasites in each species of host plant were determined. Four species of parasites,Microplitts croceipes(Cresson),Cotesia (= Apanteles) marginiventris(Cresson),Cardiochiles nigricepsVierick, andCampoletissonorensis(Cameron) were reared fromHeliothislarvae. The highest and lowest numbers of species of parasites and percentage of parasitism ofHeliothislarvae occurred in species of early season wild host plants.M. croceipesparasitized larger numbers ofHeliothisspp. larvae in more species of host plants and was active over a longer period than any other parasite species. The decline in the incidence of parasitism ofHeliothisin cotton,Gossypium hirsutumL., and soybeans,Glycine max(L.) Merr., during mid- and late season may have resulted from the rapid and vast expansion in host plant habitat and from applications of insecticides.

ISSN:1754-5692    

DOI:10.1093/ee/13.5.1167

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

The relationship between temperature and nymphal developmental rate for Wisconsin populations of the pea aphid,Acyrthosiphon pisum(Harris), was studied in the laboratory and the field. Laboratory studies provided estimates of both lower (2.73°C) and upper (26.02°C) thresholds for development. Age-specific life table parameters were also estimated for two apterous cohorts and one alate cohort exposed to field temperatures. Population growth statistics varied with rearing temperature but, for apterous cohorts, converged when a physiological time scale (“instar periods”) was used. Although stable stage (instar) distributions for the apterous cohorts varied on a physiological time scale, ca. 50% of the individuals in each cohort were first instars, whereas adults accounted for only 7.6 to 13.1% of the total population. Developmental thresholds and population statistics forA. pisumin Wisconsin were similar to an Ontario (Canada) population established in a climate similar to Wisconsin's, but were dissimilar to a British Columbia population established in a warm, arid region. The relevance of these results to the study ofA. pisumpopulation dynamics in the field is discussed.

ISSN:1754-5692    

DOI:10.1093/ee/13.5.1173

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

MaleTribolium castaneum(Herbst) produce an aggregation pheromone that attracts conspecific females. We used a two-choice pitfall trap to test the response of females from four laboratory populations to natural pheromone gathered from males of each population and to synthetic 4, 8-dimethyldecanal. Three populations were derived from animals collected 7 years ago: two in Spain and one in Yugoslavia. The fourth population had been in laboratory culture at Chicago for at least 30 years. In eight combinations of the two population choice tests, females did not discriminate between pheromone from their own population and from another population; in three of the four remaining combinations, females discriminated significantly against the stimulus from their own population. Females from the laboratory population and one Spanish population did not respond differently to different concentrations of synthetic 4, 8-dimethyldecanal. Females from the other Spanish population showed an increasing response with increasing concentration, and females from the Yugoslavian population responded most to an intermediate concentration. We discuss the possible chemical bases for these results, and their evolutionary implications.

ISSN:1754-5692    

DOI:10.1093/ee/13.5.1182

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Air-borne conidia of the fungusEntomophthora gammae(Weiser), a pathogen ofPseudoplusia includens(Walker), were sampled continuously during August and September over a soybean field using a Burkhard spore trap. Conidia were first detected 1 week before host larvae were detected. Initial collections coincided with a cool, wet period. Once larvae were found, conidia were detected daily. Peak collections occurred at intervals of ca. 9 to 12 days, and highest numbers coincided with maximum host population levels. Daily collection patterns showed that initial detection usually occurred between 2000 and 2100 hours, with maximum production between 0000 and 0600 hours and essentially no production between 1200 and 1800 hours. Detection was confined to periods of near 100%RH, which normally were present for 8 h or more nightly during the trapping period.

ISSN:1754-5692    

DOI:10.1093/ee/13.5.1186

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

The attack sites of the bark beetle,I. typographus,on Norway spruce logs were observed to be more uniformly spaced than random using nearest neighbor analysis. A computer model which simulated various degrees of uniformity in spatial distribution was compared to the observed attack pattern. The model showed that a mechanism of spacing between attacks, in which beetles need to be greater than a minimum distance of about 2.5 em away from the nearest neighbor before attacking, can explain the observed distributions in nature. In the model, the distribution of angular directions to the four nearest neighbors appeared random, regardless of the degree of uniformity in the spatial distribution. The model for the mechanism of spacing can be applied to other organisms that exhibit uniform distributions.

ISSN:1754-5692    

DOI:10.1093/ee/13.5.1191

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Infestations of both insects and mites on foliage and damaged fruit were compared in two small unsprayed dwarf apple orchards of standard and disease-resistant cultivars planted in New York state. Almost all of the fruit was injured by insects, with most of the damage caused by the apple maggot,Rhagoletis pomonella(Walsh), plum curculio,Conotrachelus nenuphar(Herbst), and internal Lepidoptera (a complex of the codling moth,Cydia pomonella[Linnaeus], Oriental fruit moth,Grapholitha molesta[Busck], and lesser applewormG. prunivora[Walsh]). In general, the disease-resistant cultivars were as susceptible to the various arthropod pests as the standard cultivars. Different insect management programs were compared in the two test orchards from 1979 to 1982. A single application of an insect growth regulator, Alsystin, at the beginning of each Bight of the codling moth was more effective in preventing damage from internal Lepidoptera than applications ofBacillus thuringiensisor pheromone disruption. Various nonrestricted conventional insecticides with relatively low toxicity to mammals were tested against the plum curculio. Three applications of methoxychlor starting when petals fell was best for controlling this pest. The most effective insect management program required four insecticide applications at a cost of 398/ha and yielded 82.7% undamaged fruit.

ISSN:1754-5692    

DOI:10.1093/ee/13.5.1201

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Possible mechanisms of resistance toN. viridulain soybeans (Glycine max[L.] Merrill), genotype PIl71444, were examined. Antibiosis was evaluated through fifth stadium and whole-life rearing of nymphs on pods of field and greenhouse-grown plants. Newly emerged adults reared on PIl71444 weighed less than those reared on ‘Davis,’ although there were no differences in the length of developmental time or mortality. There were no differences in the number of feeding sheaths deposited by adults in greenhouse no choice and laboratory choice tests with pods. However, females consistently chose ‘Davis’ over PI171444 in laboratory choice tests with leaves and pods, suggesting nonpreference for PI171444. Nonpreference, antibiosis, and temporal separation are discussed as mechanisms contributing to the high resistance to stink bugs previously reported for PI171444 in the field.

ISSN:1754-5692    

DOI:10.1093/ee/13.5.1208

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

We describe the phenology and developmental biology of the hop-vine borer (Hydraecia immanis) over a 4-year period (1979–1982) in relation to the major change in feeding habits and food availability. The first two to four instars feed on grass stems then move to adjacent corn plants to complete their feeding. In view of this feeding habit it seems likely that increasing trends toward reduced-tillage and conservation-tillage practices in the Midwest can only contribute to spread ofH. immanisin the future. In contrast, its introduced European relative (the polyphagous potato stem borer,H. micaceaEsper) has a similar biology but a wider range of host plants, including potatoes, corn, and many other plants as well as hops. This relative was introduced to North America approximately 80 years ago hut has only recently spread across Canada from New York State. We now report that it has been detected in Wisconsin where it is currently separated in noticeable economic damage from the hop-vine borer by only a single county. The implications of hybridization or continued geographic spread of these two species for Midwest agriculture may be significant and are briefly discussed.

ISSN:1754-5692    

DOI:10.1093/ee/13.5.1216

出版商:Oxford University Press    

年代:1984

数据来源: OUP