摘要:

Ipomopsis aggregatais the 2nd host plant found for larvae ofHylemyasp. Although the behavior of ovipositing females onI. aggregatais quite similar to their behavior onPolimonium foliosissimum, evidence is presented indicating that an oviposition-deterring pheromone is not being deposited onI. aggregataflowers. These females are, however, able to recognize and respond to the ovipositon-deterring pheromone deposited onP. foliosissimum. Although manyHylemyaeggs are laid on singleI. aggregataflowers ample larval resources are insured for eachHylemyalarva by a very high level of egg mortality.

ISSN:0046-225X    

DOI:10.1093/ee/9.3.321

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

Laboratory and field studies assessed how face fly,Musca autumnalisDeGeer (Diptera: Muscidae), was affected by competition among fly larvae for cattle dung. Cohorts of 1st-instar face flies were reared with known amounts of dung per individual, and then various life-history attributes of the larvae and subsequent stages were examined. The 1st symptom of competition was stunting of subsequent pupae and adults. Stunted females emerged earlier, matured later, possessed fewer ovarioles and were less fecund than their full-sized counterparts. Where competition was intense, few larvae survived to pupate, and the majority of the pupae died before adults emerged. The intensity of competition did not affect the sex ratio and longevity of flies that survived to adult. Field data corroborated the relationship between the density of coprophagous fly larvae and the size of emerging female face flies. These results indicate that competition may or may not be detected within the coprophagous guild, depending upon which life-history attributes of the suspected competitors are analyzed.

ISSN:0046-225X    

DOI:10.1093/ee/9.3.325

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

A temperature driven model based on field conditions was developed for determining the growth rates of populations of the green peach aphid (GPA),Myzus persieae(Sulzer), at high temperatures. At peak mid-summer temperatures, 2 thresholds were determined: (1) a decelerated phase of population growth (39°–46°C) and (2) a negative phase of population growth (>46°C). In 2 other runs, temperatures never reached the threshold of the phase of negative growth; however, the population growth decelerated at a lower threshold (31.6°–42.3°C) than in the mid-summer test.

ISSN:0046-225X    

DOI:10.1093/ee/9.3.331

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

Population ecology ofAphis neriiB.d.F.on oleander (Nerium oleanderL.) in northern California was assessed. A native generalist,Lysiphlebus testaceipesCresson, was the only primary parasite reared fromA. nerii, and in certain cases, it was able to control the host population. However, parasitization byL. testaceipeswas an inverse-density-dependent factor and thus not a significant mortality factor at high aphid population densities. The latter populations were apparently regulated through intraspecific mechanisms (e.g., competition). Outbreaks ofA. neriioccurred only at urban sites where plants were regularly pruned and watered. These cultural practices resulted in an increased proportion of new, actively growing terminals (preferred byA. nerii) which led to increased density of aphids feeding on such terminals. Relevance of these studies to insect ecology in urban environments is discussed.

ISSN:0046-225X    

DOI:10.1093/ee/9.3.338

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

Apameles melanoscelus(Ratzeburg) females examined gypsy moth (Lymantria disparL.) silk more intensely in the afternoon than they did in the morning, but they examined it for decreasing lengths of time the longer they were exposed to it. This decrease was not due to a buildup of deterrent chemicals deposited by the female. Parasites were reactivated by holding them without silk for 60 min, indicating that habituation was involved. Parasites also remained active longer when increasing amounts of silk or hosts in conjunction with silk were presented to them.

ISSN:0046-225X    

DOI:10.1093/ee/9.3.345

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

Microgen® application ofBacillus thuringiensis(Bt) formulations on pear compared favorably to the conventional high volume application by handgun but was dependent upon calm weather conditions for effective coverage. The viable half life of Bt spores on pear fruit was related to their placement on the fruit surface. Spores located in protected areas at the base of the fruit remained viable for a longer period (half life = 1.3–2.5 days) than did spores exposed to sunlight on the perimeter of the fruit (half life = 1.2–1.4 days).Early season control of fruit tree leafroller (Archips argyrospilusWalker) (Lepidoptera: Tortricidae) on pear using Bt formulations was attempted using both the Microgen and handgun. Both application methods had a suppressive effect on the number of rolled leaves and early fruit damage compared to the control. The amount of damaged fruit between treatments at harvest was not significantly different.

ISSN:0046-225X    

DOI:10.1093/ee/9.3.350

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

Gas chromatographic analyses of pheromone component ratios from 381 individual female tip extracts from field and laboratory populations of redbanded leafroller moths revealed that a narrow-variance signal (coefficient of variance = 9.7%) was used by both populations. Although all measured ratios of (E)-/(Z)-11-tetradecenyl acetates for both populations fell within 4–15% for theE-component, the untransformed means and standard deviations for the field and lab insects were 9.1±1.8 and 7.0±1.4%, respectively (difference significant at P<0.01). The field Insects contained an average of 139±81 ng of pheromone/female compared to 107±58 ng/female for the laboratory insects. No significant relationships were found between insect body weights, quantity of pheromone, or component ratios.

ISSN:0046-225X    

DOI:10.1093/ee/9.3.359

出版商:Oxford University Press    

年代:1980

数据来源: OUP