摘要:

A detailed mathematical model ofOstrinia nubilalis(Hübner) in maize,Zea maysL., was created for use in ecological studies. Validation results indicated that the model predicts long-term population dynamics and within-season survival relatively well. For other processes, validation results were mixed, with the best fits occurring when diapause induction was modeled accurately. The results demonstrated the importance of natural enemies, temperature, and photoperiod (latitude) to population dynamics. This simulation model is an adequate first step in the creation of a comprehensive explanatory model that can be used to guide experimentation and explore ecological principles.

ISSN:0046-225X    

DOI:10.1093/ee/17.6.969

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Several possible interactions between the parasitoidMicroplitis croceipes(Cresson) (Hymenoptera: Braconidae) and aHeliothis zea(Boddie) multiple-embedded nuclear polyhedrosis virus (HzmNPV) were investigated. FemaleM. croceipesdid not transmit the HzmNPV from infectedHeliothis zea(Lepidoptera: Noctuidae) to uninfectedH. zealarvae via oviposition. For both unparasitized and parasitizedH. zealarvae, percent virus-induced mortality decreased with increased host age at infection. PercentH. zeapupating and percentM. croceipescocoon formation both increased with increased host age at infection for unparasitized and parasitizedH. zea, respectively. Although parasitization did not decrease percent virus-induced mortality, it did increase the time to virus-induced mortality compared with that for unparasitized larvae.M. croceipessuffered high mortality when the HzmNPV killed theH. zeahost larva before the parasitoid larva had completed its development. Parasitized larvae that escaped or overcame parasitism and then pupated took significantly longer to pupate than unparasitized larvae. Implications of virus-parasitoid interactions on the biological control ofH. zeaare discussed.

ISSN:0046-225X    

DOI:10.1093/ee/17.6.977

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

A model of arthropod predation on small (second instars) velvetbean caterpillar,Anticarsia gemmatalis(Hübner), in Florida soybeans is presented. Predation is mathematically described as a function of the number of prey and predators, predator search, and soybean leaf area. Predator search was determined to be a negative exponential function of prey density whereby predators searched less area as prey density increased. Prey density was defined in consideration of the size of the predators' searching universe (the soybean leaf area) as the number of prey per square centimeter of leaf area. The influence of plant growth on predator search and predation is discussed.

ISSN:0046-225X    

DOI:10.1093/ee/17.6.983

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

The probing and feeding behavior of an important vector of barley yellow dwarf virus (BYDV), the bird cherry-oat aphid,Rhopalosiphum padiwas electronically monitored on barley varieties with and without theYd2gene, a gene that imparts BYDV resistance to certain cereal cultivars. The presence of theYd2gene was shown to have no significant effect on the time elapsed to the first sieve element contact, total number of sieve element contacts, or duration of phloem sieve element ingestion byR. padi. Furthermore, aphid probing and feeding was not greatly affected by BYDV infection in susceptible plants. These data demonstrate that the mechanisms underlying BYDV resistance in plants with theYd2gene do not involve factors significantly influencing plant-aphid interactions that invoke alterations in aphid probing or feeding behavior. In addition, the number of sieve element contacts and duration of ingestion from sieve element cells byR. padiindicate that this aphid should be highly efficient in acquiring and transmitting the phloem-delimited BYDV to ‘California Mariout’ barley, with or without theYd2gene.

ISSN:0046-225X    

DOI:10.1093/ee/17.6.988

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Anopheles quadrimaculatusSay larvae were sampled using an area sampling method along point-quadrat transects in a marsh in 1986 and 1987 to estimate absolute population density and describe larval distribution. Larvae were significantly more abundant in 1986 than in 1987, with 152.8 ± 77.1 ($\bar x$± 95% CL) larvae/m2in 1986 and 44.5 ± 21.3 ($\bar x$± 95% CL) larvae/m2in 1987. Nearest neighbor estimates of larval population density (166.5 larvae/m2for 1986; 37.1 larvae/m2for 1987) closely approximated the absolute estimates. Taylor's power law and Iwao's density-contagiousness coefficient indicated that larvae were aggregated in distribution. Regression of larval numbers on quantified habitat variables in quadrats of 1986 showed a positive relationship between length of downed, floating plant stems and larval density, where 66% of the variation in larval density was explained by variation in this variable. Direct observations of larvae showed that typical larval posture was with body perpendicular to a downed plant stem-water interface and tail-end to the interface. However, an experiment showed that larvae did not preferentially select interfaces in the laboratory.

ISSN:0046-225X    

DOI:10.1093/ee/17.6.992

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Larval and egg mass sampling along with a sex pheromone trap grid consisting of 105 traps spaced 200 by 140 m apart were used to study the population biology of the tortricid,Platynota idaeusalis(Walker), among pome and stone fruits in Adams County, Pa. Overwintering and summer populations were found beneath apple, pear, peach, and cherry on a wide variety of herbaceous plant species, especiallyTaraxacum officinalis, Rumex obtusifolius, and root suckers. In apple, larvae were found overwintering primarily beneath the tree canopy within 2 m of the trunk. Significantly more first-brood larval shelters were found on apple than on cherry, peach, or pear. However, the highest density of second-brood egg masses and male trap counts were found in cherry. No differences were found in second-brood egg mass density among five of the six apple cultivars sampled. Significantly higher fruit injury levels were found for ‘Yorking’ and ‘Rome Beauty’ than for ‘Delicious’, ‘Golden Delicious’, ‘Stayman’, and ‘Jonathan’. Fewer moths were caught in pheromone traps placed in fields and wooded sites than in orchards. Recapture of marked moths demonstrated that males moved throughout the study site.

ISSN:0046-225X    

DOI:10.1093/ee/17.6.1000

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

FemaleTrichogramma minutumRiley released from a central point in a white spruce,Picea glauca(Moench) Voss, plantation attacked eggs of the spruce budworm,Choristoneura fumiferana(Clemens), locally around the point of release. Dispersion parameters showed an aggregated pattern of attack—mean ($\bar m$), 1.6 parasitized egg masses per station; mean index of crowding (m*), 20.5; Lloyd's index of patchiness (IP), 7.3. Parasitoids dispersed a total distance of 18.5 m over 5 d, with a mean horizontal distance(d)of 4.3 ± 0.2 m and an average dispersal rate of 7.2 cm/h. Movement byT. minutumwithin trees was not affected by wind; however, dispersal between trees during the first 2 d after release tended to be downwind. Average vertical distance of dispersal within trees from a point 0.25 m above ground was 2.4 m (±0.05 m). WhenT. minutumwas released at this height in 1984, parasitism of egg masses was significantly higher at 3.25 m above ground than at 2.25 or 1.25 m above ground. The reverse was true when parasitoids were released at ground level. Greater parasitoid movement was seen on jack pine,Pinus banksianaLamb., than on white spruce. Dispersal by femaleT. minutumwas influenced by stand complexity and volume.

ISSN:0046-225X    

DOI:10.1093/ee/17.6.1009

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Heliothis virescens(F.), tobacco budworm (TBW), andHeliothis subflexa(Guenée) larvae were imported into the Stoneville Research Quarantine Facility from Argentina in 1986. These species were crossed and their response to hybridization compared with results obtained from crosses between the same species at Stoneville, Miss. Hybrids were further backcrossed to the Stoneville TBW to determine reproductive compatibility of strains from two different locations. Trends in hybrid development from crosses betweenH. subflexafemales and TBW males from Argentina were the same as those previously reported from the same crosses between the Stoneville strains. Female larvae developed slower, and pupae were much larger than males. The reverse trend was seen in progeny from reciprocal crosses, Strains from both locations were carried through five generations beginning with the ArgentinaH. subflexa× TBW hybrid and backcrossed to the Stoneville TBW male for four generations with no evidence of male fertility.

ISSN:0046-225X    

DOI:10.1093/ee/17.6.1016

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Laboratory experiments showed that the mite predatorTyphlodromus pyri(Scheuten) altered its searching behavior in response to chemical stimuli emitted or associated with European red mite (ERM),Panonychus ulmi(Koch), but did not respond similarly to stimuli fromTetranychus urticae(Koch). Study of the field distribution ofT. pyriand ERM indicated the two populations mixed randomly. The apparently incongruent laboratory and field results were reconciled by comparing the searching behavior ofT. pyriwith the previously described searching behaviors ofPhytoseiulus persimilis(Athias-Henriot) andAmblysieus potentillae(Garman) and by comparing the life history of ERM to that ofT. urticae, the preferred prey ofP. persimilis.

ISSN:0046-225X    

DOI:10.1093/ee/17.6.1019

出版商:Oxford University Press    

年代:1988

数据来源: OUP

ISSN:0046-225X    

DOI:10.1093/ee/17.6.1035

出版商:Oxford University Press    

年代:1988

数据来源: OUP