摘要:

Four phenology models that accumulate development based on daily temperature are evaluated for their ability to simulate and predict development of the pea aphid,Acyrthosiphon pisum(Harris), and the blue alfalfa aphid,A. kondoiShinji, in the field. Although the most complex of these models fits the development data best, the simpler models prove to be better at prediction. This result has important implications for the use of phenology models in the field.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.227

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

In a semi-enclosed courtyard, two Pherocon 1C traps baited with the synthetic sex pheromone ofArgyrotaenia citrana(Fernald) caught 16, 32, and 49% fewer marked maleA. citranawhen in the presence of 5, 10, and 20 virgin femaleA. citranacaged in cardboard cylinders and housed in Pherocon 1C traps, respectively, than did controls with synthetic pheromone-baited traps only. Capture efficiencies of released marked males ranged from 27–53%. Competition coefficients of virgin females calculated at three female moth densities suggested that pheromone catch per trap per night may be reduced by 2.56–3.27% per competing female. These results indicate that calling virgin femaleA. citranacan significantly affect captures of male moths in synthetic pheromone-baited traps and, therefore, may influence moth phenology and density interpretations made from these types of monitoring data in the field.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.232

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

A multinucleocapsid nuclear polyhedrosis virus (MNPV) was isolated during an epizootic in California's Merced County from a single larva of the beet armyworm,Spodoptera exigua(Hübner). Occlusion bodies produced by this virus isolate, designatedSeMNPV-608, measured 1.52 ± 0.11 µm ($\bar x$± SD) in diameter and most contained virion; with two to four nucleocapsids per envelope. Restriction enzyme profiles of viral DNA indicate that this virus is markedly different from theAutographa californica(Speyer) MNPV (AcMNPV) and fromSeMNPVs isolated from Egypt and the Netherlands, but is; similar to other previously describedSeMNPV isolates from California. Synchronous per o5 bioassays of the virus against neonate beet armyworm larvae demonstrated thatSeMNPV 608 was highly virulent, with an ST50of 57.39 ± 1.59 h ($\bar x$± SD), and more virulent for larvae ofS. exiguathanAcMNPV (ST50= 70.06 ± 2.66 h). Additionally, limited host range studies indicated that this isolate is specific forS. exiguano activity was apparent against larvae of the noctuidsHeliothis virescens(F.),Trichoplusia ni(Hübner), orSpodoptera frugiperda(J. E. Smith).

ISSN:1754-5692    

DOI:10.1093/ee/15.2.240

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

A life table ofBessa harveyi(Townsend), a parasite of yellowheaded spruce sawfly,Pikonema alaskensis(Rohwer), was constructed from field samples of eggs, firstinstar maggots, and adults. Major mortality factors of the parasite, in order of importance, were overwintering maggot mortality, superparasitism, egg infertility and sloughing, and fall emergence. Overwintering mortality included flooding, desiccation, freezing, predation, encapsulation by the host, and failure of adult flies to exit host cocoons. No obligatory diapause was detected whenB. harveyimaggots were reared in the host at room temperature (21–22°C) and under constant light. The mean time for maggot development was 8.4 days (SE = 0.33). The sex percentage of 151 laboratory-reared puparia was 51.7% females. TotalB. harveyiparasitism onP. alaskensislarvae was 16.7% in 1978 and 21.2% in 1979.B. harveyiis not well adapted toP. alaskensis. Therefore,B. harveyiis a polyphagous parasite that concentrates on the most predominant host in its range. We conclude that no practical method of improving the effectiveness ofB. harveyionP. alaskensiscurrently exists.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.246

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Developmental rates of egg and pupal stages ofMonochamus carolinensis(Olivier) were determined for six temperatures ranging between 18–38 and 22–40°C, respectively. Development was minimal below 22°C, while maximal rates occurred at 34°C for eggs and 32°C for pupae. Regression equations relating temperature (x) to development rates (y) for egg and pupal stages werey= −0.1247 + 0.0116 (x) andy= −0.0725 + 0.0067 (x), respectively. Lower developmental threshold was 10.7°C for eggs and 10.8°C for pupae. Mean number of thermal units above 10.6°C necessary for egg-to-adult development was calculated to be 972 for insects reared under ambient conditions. Thermal unit accumulation above 10.6°C between 1 January and 31 December 1982 was 2,017 at Columbia, Mo.; thus,M. carolinensiscould pass through two generations per year. This conclusion was supported by field observations.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.251

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Populations ofAdelges cooleyi(Gillette) were assessed for spatial and seasonal abundance on young Douglas-fir trees. Four sampling techniques (1-min, 3-min, 5-branch, and 15-branch counts) were evaluated for the relative accuracy in estimating adelgid densities. Counts ofA. cooleyiwere consistently greater on the upper two-thirds of trees throughout the season. Early summer (July) populations were higher on the northern and eastern aspects of trees, but became more evenly distributed as summer progressed (September). All four sampling techniques were relatively consistent at the various sampling periods. The 3-min count recorded the largest number of adelgids and was most accurate in assessing late season, declining populations. Selection of the sampling technique to use depends on the purpose for which results will be used (e.g., monitoring numerical changes or simply an indication of trends).

ISSN:1754-5692    

DOI:10.1093/ee/15.2.254

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

The yellowheaded fireworm,Acleris minuta(Robinson), is a multivoltine pest of rosaceous and ericaceous plants. Larval development of both sexes may proceed through five, six, or seven stadia. In field populations, the five-instar mode is more prevalent during first, second, and third generations; frequency of the six- and seven-instar modes increases during the fourth generation. Reduced growth rates increase frequencies of supernumerary molts. A discriminant function based on head-capsule size and sex classified 70% of the laboratory population under the proper mode of development. This discriminant function was used to classify field populations into the proper mode of development.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.258

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Seasonal abundance and incidence of parasitism of nymphs and adults of brown planthoppers,Nilaparvata lugens(Stål), whitebacked planthoppers,Sogatella furcifera(Horvath), and green leafhoppers,Nephotettix nigropictus(Stål) andN. virescens(Distant), in rice fields were monitored in 12 locations in Laguna Province, Philippines, during the 1983 wet season (July to November) and the 1983–1984 dry season (December to April). Overall percent parasitism was low and variable among seasons and locations.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.263

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Dispersion analysis with Taylor's power law was used in development of binomial sampling plans for larvae ofLiriomyza trifolii(Burgess) in chrysanthemums. Covariance analysis showed that variance/mean relationships were consistent between different plant strata and between a plot that contained only one chrysanthemum cultivar versus a plot that contained seven different cultivars. Comparison of a constant precision sample (C= 0.10) and a fixed sample size of 100 leaves showed that the fixed sample size provided better estimates of mean population level. The utility of a sampling plan that allows rapid assessment of immature leafminer population levels in a pest management system is discussed.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.268

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

A laboratory experiment showed that preferences ofMicroplitis croceipes(Cresson) for certain larval instars ofHeliothis virescens(F.) may arise in part from variation in probability of parasitization once a parasitoid encounters a host. Host acceptance was higher and handling time shorter for preferred host instars. In support of the hypothesis that parasitoids choose host stages that maximize fitness, development rate was faster and adult head width of wasps was larger for wasps from hosts parasitized in preferred instars. However, the number of oocytes was smallest in wasps from hosts parasitized in the most preferred instar, suggesting a trade-off between development rate and fecundity. Furthermore, egg/larval mortality, pupal mortality, and adult mortality increased monotonically with host instar parasitized. Although the fitness components measured did not relate simply to instar preferences, reasons were found for avoidance of first instar and fifth instar hosts, the least preferred instars.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.274

出版商:Oxford University Press    

年代:1986

数据来源: OUP