摘要:

Dendrolaelaps neodisetus(Hurlbutt) completed its development in 144 to 312 h at 25°C. Longevity of adults ranged from 14 to 105 days for females and 11 to 113 days for males. After a preoviposition period of 1 to 2 days, females laid an average of 3.38 ± 0.47 eggs per day, with a maximum of 68 for any individual. Hatching varied from 48 to 168 h. Larval and protonymphal instars lasted 24 to 120 and 24 to 96 h, respectively. Some individuals remained in the deutonymphal (phoretic) stage for 6 to 119 days, whereas others molted to adults after 24 to 96 h. All active instars preyed on nematodes.

ISSN:0046-225X    

DOI:10.1093/ee/13.4.1141

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Preference ofMicroplitis croceipesfor five instars ofHeliothis zeaandH. virescenswas measured experimentally on cotton in field cages.M. croceipesshowed strong host-instar preferences. Using Manly's measure, we found wasps preferred third-instar larvae most (b= 0.47), fourth- and second-instar larvae next (b= 0.23 and 0.21, respectively), and first- and fifth-instar larvae least (b= 0.04). Preference did not depend on total host density or on the density of the most preferred instar. The wasps did not prefer one host species over the other. The sex ratio of the wasps was not affected significantly by the instar parasitized. However, wasp development time depended on instar parasitized. Development time in an instar was also inversely correlated with preference for that instar, suggesting that selection for rapid development has contributed to the observed pattern of preferences. We present a model that predicts the proportion of larvae parasitized by the end of each instar, and thus the proportion of a host cohort parasitized in the field. The model requires as input the instar preferences of a parasitoid and an estimate of the density of searching parasitoids; it predicts parasitization fairly well in a collection of larvae from the field.

ISSN:0046-225X    

DOI:10.1093/ee/13.4.1145

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

The percentage of spotted knapweed,Centaurea maculosaLamarck, seed heads infested withUrophora affinisFrauenfeld and the average number ofU. affinisgalls per seed head increased significantly over a 4- to 6-year period at six sites in western Montana.U. affinisinfestation percentages of 99% were recorded within 50 m of the fly release points at two sites in 1981. Differences inU. affinisnumbers with respect to distance and direction were less consistent. Up to 24 galls were found in individual seed heads. Spider and rodent predation, in addition to an unusually cold winter, were possible factors adversely affectingU. affinispopulations. No apparent correlation was observed betweenU. affinisnumbers and spotted knapweed flower head density at sites whereU. affiniswas well established.

ISSN:0046-225X    

DOI:10.1093/ee/13.4.1151

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Larval development rates of the alfalfa seed chalcid in differentMedicago sativaclones were compared, and factors affecting field infestations were tested. Development rates did not differ significantly. Variation in field infestations is probably dependent on factors affecting oviposition. Temperature, daylength, and resource competition affected field infestation levels and were associated with diapause. Larval diapause appears to be induced in the female parent.

ISSN:0046-225X    

DOI:10.1093/ee/13.4.1157

出版商:Oxford University Press    

年代:1984

数据来源: OUP