摘要:

One of the most common methods of studying insect dispersal is the recapture of members of a population released at a single time from a single location. This procedure especially lends itself to quantitative analysis. Quantitative studies of the dispersal of insects released in this manner may be divided into the following three general categories: (1)statistical studies in which certain dispersal parameters such as average distance flown are estimated without assuming any particular model; (2) curve fits to an empirical model having a predetermined functional form, such as an exponential; and (3) fits to a fundamental biological model such as a diffusion-based model. Each of these methods of analysis serves a purpose. For example, the first and second methods are often useful in developing control strategies for invasive pest species, whereas the third is useful for understanding the biological process driving dispersal. The article presents a quantitative analysis of the dispersal of irradiated Mediterranean fruit flies,Ceratitis capitata(Wiedemann) in a macadamia nut orchard near Hilo, Hawaii. All three of the methods described above are used in the analysis. The article had three primary objectives. The first was to review and contrast the three methods of analyzing data on the dispersal of insects from a point source. The second was to illustrate how these methods may be applied to insect recapture data using the example of released Mediterranean fruit flies. The third was to use the quantitative analysis to compare the results of the present release study with other studies on related species and to draw general conclusions about the nature of the dispersal of released sterile Mediterranean fruit flies. Results indicated that a population of irradiated flies released from a single point dispersed in a manner that may be modeled as if the population consisted of two subpopulations, one of which was dispersing in a diffusionlike pattern and the other was not dispersing, and that the fraction of the population in the nondispersing subpopulation increased. The dispersal pattern appeared to be little influenced by prevailing wind and to remain centered near the release point. The pattern had almost complete circular symmetry.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1493

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

A 4-yr study was conducted to examine the phenology of rangeland grasshoppers at 12 sites throughout Montana. A six-species complex of common and economically important rangeland grasshoppers was selected to facilitate comparisons between sites in this environmentally heterogeneous state. Results showed that a published phenology model (developed by Dennis, B., W. P. Kemp&R. C. Beckwith. 1986. A stochastic model of insect phenology: estimation and testing Environ. Entomol. 15: 540–546, and Dennis, B.&W. P. Kemp. 1988. Further statistical inference methods for a stochastic model of insect phenology. Environ. Entomol. 17: 887–893) provided good estimates of “general” grasshopper phenology for each site and year. Comparisons of developmental “signposts” (75% first instar, peak second to fifth instars, and 75% adults) for grasshoppers between sites and years indicated that they can be used by resource managers for estimating when development stages of rangeland grasshoppers are likely to occur. The developmental signposts were separated, on average, by 8–12 d. Implications of these results for rangeland insect pest management are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1504

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The ability to predict larval phenology for the gypsy moth,Lymantria dispar(L), is of interest for a variety of reasons, ranging from basic ecological research applications to the applied objective of improving timing of spray applications. Problems with the development of an appropriate model to predict larval phenology for this pest are exacerbated by the large, and often complex, landscapes that must be considered in control programs, and by the gypsy moth's extensive geographic distribution. The goal of research discussed in this paper is to provide a flexible modeling system that can be used to construct a phenology model that is well suited for a particular application. To accomplish this goal, parameters for a variety of developmental models from an existing data base were estimated. Basic modeling assumptions, such as the instar independence of developmental rates, were tested. Parameter estimation for the set of reasonable models resulted in a large number of potential phenology models. To assist in the development of an effective predictive tool, a modeling system was designed for assembling and implementing selected models. Finally, several applications were discussed that illustrate the rationale for choosing the most appropriate model for a particular application. Our primary objective is to provide a convenient modeling framework for field testing and applying gypsy moth larval phenology models.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1516

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

At a 1-m depth in the soil, temperatures remain at a relatively constant value (mean average of the surface temperature) with only a total daily fluctuation of 1°C. This temperature range was found to be practical for use in incubating insects that were treated with insecticides for toxicity studies, especially in resistance monitoring programs. Groups of 24 d-old male susceptible pink bollworms,Pectinophora gossypiella(Saunders), were mired in insecticide-laced sticky cards or placed in 20-ml scintillation vials coated with the following insecticides: fenvalerate, permethrin, and monocrotophos. When incubated in the bottom half of a hole in the ground 1 m deep outside of our laboratory at Riverside, Calif., in the middle of summer, results were comparable to incubation of similarly dosed insects in environmental chambers. Control mortality was negligible for pink bollworm adult males held in untreated scintillation vials at constant temperatures from 16.5 to 40°C for 2 d. Thus, storing treated insects in simple holes in the ground is a valuable new tool in resistance monitoring by eliminating the transport of insects away from field pheromone traps and other collection sites.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1526

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Resistance to an endophyte,Acremonium coenophialumMorgan-Jones&Gams, and management tactics were evaluated against several leafhopper species under field conditions. ‘Georgia-5’ tall fescue,Festuca arundinaceaSchreb., was planted to a randomized block design split plot with a factorial arrangement of pest management treatments in the subplot. Leafhopper and froghopper populations were monitored throughout the year by taking sweep samples approximately every 2 wk. Of the 28 species of leafhoppers and froghoppers collected, 6 species of leafhoppers and 1 species of froghopper comprised over 80% of the specimens collected. With the exception of the nematicide treatment, there was no significant difference in leafhopper population densities due to chemical treatments. Four species of leafhoppers and one species of froghopper showed significantly higher population densities on endophyte-free tall fescue when compared with the endophyte-infected tall fescue plots. The greatest differences between endophyte-free and endophyte-infected tall fescue plots occurred at leafhopper peak seasonal densities. Although chemical treatments apparently have little effect on leafhopper population densities, theAcremoniumendophyte provides tall fescue with resistance against some leafhopper species.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1531

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Damage by tobacco hornworm larvae,Manduca sexta(L.), was simulated with artificial clipping techniques. No significant change in photosynthesis per unit area of leaf was detected in response to damage by tobacco hornworm or clipping techniques. Whereas significant negative regressions were obtained between plant growth and percent defoliation, the effects of tobacco hornworm and clipping were not significantly different. Peak effects of defoliation on all growth parameters appeared on day 36, yet the effects were starting to diminish. The effects of each type of defoliation regime were not statistically different from each other for dry-weight accumulation within any plant part. Defoliation treatments caused reductions in total dry weight attributable to decreased accumulation, primarily within existing vegetative and root structures. Leaf dry-weight accumulation was the most sensitive aboveground variable to defoliation. Ecologists contemplating techniques to simulate herbivory are urged to compare real and simulated herbivory for specific variables of interest. Studies that address the adequacy of particular herbivore-model pairings may ultimately prove cost-effective and allow for proper testing of questions that cannot be addressed with real herbivory.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1537

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Canopy arthropods on dogwood,Cornus floridaL.; red maple,Acer rubrumL.; and yellow poplar,Liriodendron tulipiferaL., were bag-sampled during the day and night on six dates from July through September 1986 in the southern Appalachians of North Carolina. Diurnal and nocturnal comparisons were made for arthropod community composition and similarity. Overall numbers of canopy arthropod taxa were similar both between and within tree species, as was relative taxon abundance as assessed by community diversity measures. However, there were substantial differences in faunal composition and weighted arthropod numbers between daytime and nighttime canopies. Diel differences in canopy faunal composition is related to differential periods of activity among some canopy arthropods. These data suggest that canopy foliage may support greater densities and kinds of arthropods than those previously reported based on daytime sampling only. Experimental designs that include diel sampling would provide a more complete assessment of the structure and composition of canopy communities by taking into account the dynamic component of these communities.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1542

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The population dynamics of the Colorado potato beetle,Leptinotarsa decemlineata(Say), were studied in central Mexico in 1987 and 1988. During the June-October rainy season, three generations were observed in 1987 and two in 1988. Predation and parasitism were found to be important mortality factors, particularly late in the season, contributing to generation mortality as high as 99.8%. Time series cross-correlation was used to estimate synchrony of Colorado potato beetle eggs with predators. Predators, including asopine pentatomids, carabids, thomisid spiders, and coccinellids, were abundant and well synchronized with developing Colorado potato beetle late in 1987, corresponding to the period of highest mortality.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1549

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

On Guam, mango trees are damaged by mango shoot caterpillar,Penicillaria jocosatrixGuenée. Growth variables were measured on trees defoliated by the caterpillar, and on trees that were protected by application of carbaryl. Mango shoot caterpillars removed 54% of the foliage of untreated trees compared with 10% in treated trees. Treated trees produced new foliage about twice during the year, whereas damaged trees flushed four times. Shoots on damaged trees were shorter and initiated fewer leaves, but the size of the leaves was not affected. There was a significant negative association between severity of damage to a shoot and interval until new shoot initiation. Shoots that flushed out of synchrony with the majority suffered heavier caterpillar damage. Untreated trees compensated for damage by producing additional flushes, but at the end of one year they still had one-third less foliage than treated trees. At the end of one year, trees that had a leaf area<4–5 m2per 25 shoots did not flower in response to an inducer.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1556

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Three groups of mountain pine beetles,Dendroctonus ponderosaeHopkins, were placed in fresh lodgepole pine,Pinus contortaDouglas var.latifoliaEngelmann, billets and allowed to construct egg galleries. Group I consisted of reemerged females that had previously made egg galleries in the field; group II consisted of new females allowed to mate, then males were removed; and group III consisted of new females with males present throughout gallery construction. Offspring from these rearings were compared by gallery section for brood production, rate of emergence, size, and sex ratio. Reemerged females were as successful in establishing galleries as new females but produced significantly fewer beetles than new females with males present. Offspring of new females emerged at a faster rate than those of reemerged females. Offspring from reemerged females were larger than those of group II females, but not those from group III females. Sex ratios were not significantly different among offspring of the three groups.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1562

出版商:Oxford University Press    

年代:1991

数据来源: OUP