摘要:

Nine sets of serial long-term density data for 4–24 species on two continents are examined for two types of synchronous fluctuation: congruent and incongruent. Comparing product/moment correlation coefficients for species pairs with corresponding values derived from matched controls is the basic method of synchrony detection. Congruent synchrony or fluctuation in unison is weakly to strongly expressed above the random level in all data sets. Evidence of incongruent synchrony is scant, but isolated examples of two subtypes are apparent. Congruent synchrony implies commonality of population dynamics among moderate numbers of species, and pervasive density-governing mechanisms.

ISSN:1754-5692    

DOI:10.1093/ee/15.3.443

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Control of the alfalfa blotch leafminer,Agromyza frontella(Rondani), in the United States by exotic parasites is an example of classical biological control. This project was analyzed to identify research principles for future projects. Key events that influenced research were 1) identification of the pest; 2) establishment of a specific project without other research objectives; 3) development of recovery techniques; 4) determination that an empty ecological niche existed in the invaded region; and 5) parasite release procedures. Of 14 species introduced, 3 were established:Dacnusa dryas(Nixon) (Braconidae),Chrysocharis punctifaciesDelucchi (Eulophidae), andMiscogaster hortensisWalker (Pteromalidae). The effective braconid and eulophid species were r-strategists with some K-oriented characteristics, were multivoltine, utilized alternate hosts, occupied a previously vacant niche in the invaded area, were intrinsically superior competitors and long lived, had high searching capacities, and were from many localities in Europe. Benefit in 1983 was 13 million; research cost was ca. 1 million. Research approaches, parasite selection, life table studies, and role of alternative hosts are considered.

ISSN:1754-5692    

DOI:10.1093/ee/15.3.448

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Effects of agroecosystem diversification on searching behavior and success of arthropod natural enemies are poorly understood. Crop diversification may increase generalist enemy effectiveness by increasing alternate food or prey availability, as predicted by the enemies hypothesis. But diversification may also reduce enemy searching efficiency and destabilize predator/prey interactions. Additionally, specialist enemies, often important in biological control programs, may be particularly sensitive to vegetation texture. Pest control by specialist enemies may be more effective in less diverse agroecosystems if concentration of host plants increases attraction or retention of these enemies.

ISSN:1754-5692    

DOI:10.1093/ee/15.3.456

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

A laboratory technique is described in which “soft” radiographs are used to study wireworm,Melanotus communisGyllenhal, movement patterns within a soil matrix. Advantages of this technique as compared with destructive sampling are discussed and examples of several possible applications are given.

ISSN:1754-5692    

DOI:10.1093/ee/15.3.462

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Late third instars of Mediterranean fruit fly,Ceratitis capitata(Wiedemann); melon fly,Dacus cucurbitaeCoquillett; and oriental fruit fly,D. dorsalisHendel, that had exited the media to pupate were exposed to five concentrations ofSteinernema feltiae (=Neoaplectana carpocapsae)ranging from 500,000 to 5,000 per cup. Mean corrected percent mortalities 6 days after exposure ranged from 92 to 9% for Mediterranean fruit fly, 85 to 9% for the oriental fruit fly, and 86 to 0% for melon fly. Emerging Mediterranean fruit fly adults were marginally susceptible at 0.2% verified infection, and pupae in puparia were not susceptible toS. feltiae.

ISSN:1754-5692    

DOI:10.1093/ee/15.3.465

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Objectives of the study were to evaluate impact of the egg parasitoid,Anaphes sordidatus(Girault), on its host, the carrot weevil,Listronotus oregonensis(LeConte), in the field. Mortality of carrot weevil larvae, in the absence of parasitism, was found to be density-dependent, with an average of 1–2 eggs surviving per carrot plant, regardless of initial egg density. Larval density averaged 1.5 per infested plant over the season.A. sordidatusadults emerged from 22.3% of eggs collected (maximum 49.3% on 1 August). There was no significant correlation between percentage of parasitism and egg density or plant growth characteristics. Since density-dependent mortality occurred in the absence of parasitism, the concept of effective parasitism (reduction in damage or larval survival) was developed to predict the overall effect ofA. sordidatuson the carrot weevil.

ISSN:1754-5692    

DOI:10.1093/ee/15.3.469

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

We measured the relation between search rate ofMicroplitis croceipes(Cresson) and density of third instars of its hosts,Heliothis zea(Boddie) andHeliothis virescens(F.). We released wasps in field cages containing various densities of host larvae on wild host plants (chieflyGeranium dissectumL.) in spring and on cotton (Gossypium hirsutumL.) in summer. Number ofHeliothisspp. larvae parasitized increased linearly over the range of host densities used. Such responses may be more common than has recently been assumed. A simple search model first proposed by Nicholson&Bailey (1935) fit the data well. Search rate was 0.20 ± 0.03 m2per day (mean ± SE) in spring and 0.55 ± 0.04 to 0.87 ± 0.09 m2per day in summer. Neither air temperature nor host-plant size explained these differences completely.

ISSN:1754-5692    

DOI:10.1093/ee/15.3.476

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Temporal and spatial activity patterns of adultGlypta fumiferanae(Vierick) were assessed through use of malaise traps placed in tree canopies and on the forest floor. Many parasitoids were trapped in the tree canopies while none was caught on the forest floor. A model that related malaise trap catches to weather was used to draw inferences from these data. It was concluded that cool wet weather inhibited activity of the parasitoid. Historical data on interaction betweenG. fumiferanaeand its host were used to illustrate the possibility that reductions in parasite activity due to weather factors led to reductions in rates of parasitism.

ISSN:1754-5692    

DOI:10.1093/ee/15.3.481

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Distribution of the melon fly,Dacus cucurbitaeCoquillett, was determined by trapping males at 330 sites throughout the island of Kauai. Melon flies were most numerous at coastal trap sites, particularly along the south and west coasts. The Waimea Valley site located on the southwest coast was the one with the highest trap catch. Lowest catches were made at the highest elevations at the center of the island. Trap catches declined sharply with increasing rainfall and increasing elevation. However, during the seasonal peak in abundance in late summer, a few flies were trapped in the higher elevations where no host plants were present. These flies were evidently migrating rather than breeding flies. Melon fly distribution was related to distribution of its host plants. Distribution of the fly was largely along coastal areas of the island where host plants were present in commercial and backyard gardens. The melon fly was also present in noncultivated areas where the wild host,Momordica balsaminaL., was located along edges of fields and roadsides.

ISSN:1754-5692    

DOI:10.1093/ee/15.3.488

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

A model for pink bollworm (PBW) diapause in response to decreasing photoperiod and fluctuating temperatures developed in California using a wild Arizona biotype is used to explain diapause induction, termination, and adult flight phenology of PBW under Brazilian conditions. The model suggests that the Arizona and Brazil biotypes do not differ in their diapause response, which is considerably broader than required to survive the conditions in the areas examined.

ISSN:1754-5692    

DOI:10.1093/ee/15.3.494

出版商:Oxford University Press    

年代:1986

数据来源: OUP