摘要:

A BASIC computer program (DEGDAY) for calculating degree-days on microcomputers is presented. The program calculates heating degree-days with the rectangle, triangle, and sine wave methods and calculates cooling degree days with the sine wave method. Assumptions and approximations associated with degree-day calculations are noted. In particular, eight factors affecting degree-days are discussed: 1) substrate availability, 2) enzyme availability, 3) approximations in laboratory estimates of development, 4) approximations in calculating the developmental minimum, 5) approximations in calculating a developmental maximum, 6) approximations in using single values for thresholds, 7) thermoregulation, and 8) limitations of temperature data. The various errors arising from these factors are discussed in relationship to error attributable to differences between actual and estimated degree-days.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.999

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Predation of lepidopterous larvae in corn agroecosystems was examined by observing tethered live larvae over several 24-h periods. There were significantly more attacks on larvae and more larvae were consumed in no-tillage systems compared with conventional tillage treatments. Predator activity (number of attacks) and predation were greatest at night and least in early afternoon over the entire season and generally increased as the season progressed. The soil insecticide phorate significantly decreased predators and number of pest larvae consumed for ca. 2 months after its application. Large carabids (≥ 15 mm) were the most important predatory arthropods in these agronomic systems; however, noncarabid species also provided significant predation. Significant correlations were found among carabid activity, absolute density estimates of carabids, and number of lepidopteran larvae consumed in these corn agroecosystems. These high correlations indicate that the technique demonstrated the potential of endemic predatory arthropods to reduce soil larvae pests significantly.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1017

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Duration of immature stages of seedcorn maggots (SCM),Delia platura(Meigen), and bean seed maggots (BSM),D. florilega(Zetterstedt), was determined at eight constant temperatures from 5 to 40°C. No SCM or BSM survived to second instar at either 5 or 40°C. No BSM survived to the adult stage at 35°C. Duration of immature stages varied from 240 days at 10°C to 17 days at 35°C. A computer model developed using the SCM development rate data closely simulated SCM development in the field during the growing season.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1022

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Emigration rates ofEvarthrus sodalisLeConte andHarpalus pennsylvanicusDeGeer were compared in fenced tomato monocultures and polycultures of tomatoes and bean plots grown at two plant densities, as suggested by results obtained from pitfall traps in southern Michigan. Results show higher emigration rates at low plant-density treatments and a negative interaction between density and diversity (cropping system). In high plant-density treatments the emigration rate was higher in polycultures than in monocultures. The reverse was true for low-density treatments.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1028

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Performance ofGeocoris punctipes(Say) nymphs was studied on the pest-resistant soybean,Glycine max(L.) Merrill, genotypes PI 171451 and PI 229358, and pest-susceptible ‘Bragg’ and ‘Govan’.G. punctipesnymphal growth rate decreased when the insect food was velvetbean caterpillar (VBC),Anticarsia gemmatalisHübner, reared on ‘Bragg’, PI 229358, or PI 171451. Mortality of nymphs increased when they fed on PI 171451- or PI 229358-reared VBC larvae. Direct effects of plant food as detached leaflets included increased nymphal development time and increased nymphal mortality. Development time of nymphs was increased on a diet that included PI 171451 leaf and PI 171451- reared soybean looper,Pseudoplusia includens(Walker)

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1032

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Impact of predaceous insects on populations of filbert aphid,Myzocallis coryli(Goetze), in the field was determined by chemical and mechanical exclusion methods. Filbert trees from which predators were excluded had significantly higher aphid populations than trees with predators. Feeding potential of one coccinellid,Adalia bipunctata(L.), and three mirids,Deraeocoris brevis(Uhler),Heterotoma meriopterum(Scopoli), andCompsidolon salicellum(Herrich-Schaeffer), was determined in the laboratory. Predators consumed from 5 to 65 aphids daily, with the coccinellid consuming more than the mirids. Data show that the predator complex is an important factor regulating aphid populations in filbert orchards of Oregon.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1037

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

In Oregon, winter moth,Operophtera brumata(L.), is distributed throughout the northern region of the Willamette Valley, where it is commonly found on commercial hazelnut,Corylus avellanaL.; crabapple,Malus silvestrisMill.; and flowering plum,Prunus cerasiferaJ. F. Ehrh. Adults emerge in early November through December, eggs overwinter, larvae eclose in mid-March and develop through five instars, and pupae occur in the soil from May to November. Six species of native parasitoids were reared from field-collected larvae, but parasitism averaged only 4.5 and 12.2% in 1980 and 1981, respectively. The exotic parasitoidsCyzenis albicans(Fallén) (Tachinidae) andAgrypon flaveolatum(Gravenhorst) (Ichneumonidae) were released for biological control of winter moth in 1981 and 1982.C. albicanswas recovered from four of seven release sites. NoA. flaveolatumhave been recovered

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1042

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Fungicides triforine, triflumizole, and DuPont 6573, and the acaricide hexythiazox were tested for honey bee toxicity and effect on bee foraging and pollen viability in blooming apple and pear. None of the materials was toxic to honey bees or reduced bloom visitation. Only a high rate of hexythiazox significantly reduced apple pollen germination. Pear pollen germination was significantly reduced by triforine, hexythiazox, and triflumizole. Ramifications to fruit set are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1047

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Field tests were conducted withHylobius abietis(L.) in Sweden during 1982 and 1983 to study how weevils feeding on host material affect attractivity of this host material to otherH. abietisPitfall traps baited with a combination of male or female weevils and cut stems of Scots pine caught more weevils of both sexes than pine alone. Weevils of either sex were not attractive in absence of host material. Attractivity of ground phloem containing weevil frass was not significantly different from that of ground phloem alone. In a laboratory test, feeding by weevils of either sex on pine about doubled the release of monoterpene hydrocarbons and ethanol compared with pine alone. Existence of an aggregation pheromone could not be confirmed. We suggest that weevil aggregations are formed in response to host volatiles and that weevil feeding increases amounts of these volatiles released.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1050

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Overwintering behavior ofBoisea rubrolineatus(Barber) was studied during 1984–85. Large numbers of this insect aggregated on a single, large Douglas-fir,Pseudotsuga menziesii(Mirb.) Franco, tree, with deep bark fissures, at the edge of a stand ca. 1 km from a grove of maples,Acer macrophyllumPursh, the feeding host. Other trees near the overwintering site were smaller and lacked deep bark fissures, or were shaded by trees along the edge of the stand. Density measurement was used to estimate number of overwintering insects at ca. 8,000. These results demonstrate the degree of aggregative behavior in this insect and suggest that aspects of stand structure influence the availability of suitable overwintering sites.

ISSN:1754-5692    

DOI:10.1093/ee/15.5.1055

出版商:Oxford University Press    

年代:1986

数据来源: OUP