摘要:

Commercial fields of sweet corn in coastal southern California were sampled for corn earworm,Heliothis zea(Boddie), eggs in 1986 and 1987. Staggered planting schedules within each study site produced fields of varying maturity that overlapped in occurrence. Using stepwise regression, we quantified the dependence of egg density on field size, adult population level as estimated with pheromone traps, and field maturity as estimated by plastochron index. Also included were three variables associated with the probability of female moths finding a more suitable host: the hectares of older corn available, distance to the closest older cornfield, and the mean distance to all older cornfields. We found egg density to be significantly related to field maturity and the distance to the closest older cornfield. In 1987, when the average distance between fields was less than in 1986, egg density was more closely associated with field maturity and, therefore, host suitability. These results are discussed in relation to optimal oviposition theory.

ISSN:1754-5692    

DOI:10.1093/ee/17.4.722

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

The influence of soybean seed protein and oil level on developmental time, weight, and survival of southern green stink bug,Nezara viridula(L.), was examined. Developmental times and weights of adults and nymphs were similar to those reported by other researchers. Diet had a small but significant effect on developmental time to second, third, and fourth instar, with consumption of higher protein (lower oil) resulting in decreased developmental time (e.g., days to fourth instar = 13.3 on high protein diet compared with 15.2 on low protein diet). However, developmental time from hatch to fifth instar and adult was not significantly affected by diet. Maximum differences between diets at any life stage were only 2 d. Males and females had similar developmental times. Increasing seed protein resulted in greater adult weights of both males and females (e.g., weight of females = 182.2 mg on high protein diet compared with 153.0 mg on low protein diet) but had no effect on weights of nymphs. Females were significantly heavier than males from fourth instar to adult. Stink bug genotype (blocks) significantly affected developmental time and weight of all nymphal instars and adults. Survival was not affected by diet or stink bug genotype.

ISSN:1754-5692    

DOI:10.1093/ee/17.4.727

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Collections ofOpuntiaspp. (Cactaceae) cladophylls infested withDactylopius confusus(Cockerell) from two sites in west central Texas during 1982–84 yielded seven natural enemies, all predators. Major predators wereLaetilia coccidivora(Comstock),Leucopis bellulaWilliston, andHyperaspis trifurcataSchaeffer. Several parasites and hyperparasites were reared from these predators. No parasites or pathogens ofD. confususwere detected. Continuous exclusion of natural enemies from cladophylls artificially infested withD. confususresulted in high densities ofD. confusus.When natural enemies were continuously admitted for comparison,D. confususpopulations remained below the original infestation levels, and natural enemies admitted afterD. confususpopulation densities had increased through at leastone generation resulted in an immediate decrease in theD. confusesdensity. When natural enemies were continuously excluded fromD. confusus-infestedcladophylls, up to 81% of the cladophylls became necrotic, and only 4% produced new growth the following spring. However, where natural enemies were admitted, only 8%of the cladophylls manifested necrosis, and 75% produced new growth.

ISSN:1754-5692    

DOI:10.1093/ee/17.4.730

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Rates of house fly,Musca domesticaL., destruction byCarcinops pumilio(Erichson) adults andMacrocheles muscaedomesticae(Scopoli) females at two densities in a poultry manure substrate were determined at 27°C as a function of prey availability, and models based on the disk equation of Holling fit the observed data closely (R2>0.92). Asymptotic predation rates were 54 fly immatures destroyed per predator per day forC. pumilioand 17 and 11 forM. muscaedomesticaeat 5 and 20 mites per assay container, respectively. At 15 and 33°C, predation rates ofC. pumiliowere 12.3 and 82.7 per day, respectively, and those ofM. muscaedomesticaewere 5.0 and 36.3 per day, respectively.C. pumiliodestroyed significantly fewer house flies when acarid mites (Caloglyphussp.) were present as an alternative prey than when only fly immatures were present; there were no reductions in predation on the house fly in the presence of nematodes (Diplogasteroidessp.) or sphaerocerid (Coproica hirtulaRondani) immatures.M. muscaedomesticaedestroyed significantly fewer house flies when nematodes and sphaerocerids were present than when only fly immatures were present; there was no reduction in predation on the house fly in the presence of acarid mites.

ISSN:1754-5692    

DOI:10.1093/ee/17.4.739

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

The responses of male and femaleMicroplitis croceipes(Cresson) (Hymenoptera: Braconidae) to volatiles fromHeliothis zea(Boddie)(Lepidoptera: Noctuidae) larvae feeding on cowpeas were examined in a flight tunnel. The flight response of ovipositionally experienced female parasitoids to individual components and the removal of individual components (i.e., larvae, leaves, and feces) from the plant-host complex was examined. The flight response to control odors, larval feeding damage, and artificial leaf damage also was studied. Larval feces was the most important component of the plant-host complex in the initiation of flight, oriented flight, and landing on the odor source. Artificial leaf damage had an inhibitory effect on these behaviors. There was no treatment effect on flight durations.

ISSN:1754-5692    

DOI:10.1093/ee/17.4.745

出版商:Oxford University Press    

年代:1988

数据来源: OUP