摘要:

The developmental rate of insects is an important parameter in studies of insect population dynamics as well as in biological and chemical control of agricultural pests. Traditionally, models used to predict developmental rates are empirical functions of temperature. Such models are limited from a theoretical perspective because they are not explanatory and fail to include the known effects of variables other than temperature in determining developmental rate. A new approach is developed here that is based on the assumption that each species has a characteristic size (mass) at the completion of its larval or nymphal stage and that the rate of growth to this ultimate size determines the rate of development. Growth rate is modeled as a function of consumption rate and respiration (influenced by temperature) as well as approximate digestibility (influenced by diet quality). An analytic solution of this growth rate model gives the developmental rate as a function of temperature and diet quality. This approach was applied to a grasshopper,Melanoplus sanguinipes. Reasonable parameter choices generated a realistic developmental rate curve. Advantages of this approach over previous models include (1) the model is mechanistic and explanatory, (2) development is a function of nutrition as well as temperature, (3) the parameters have clear ecological meanings and are, for the most part, directly measurable, and (4) variable weight at the end of the life stage can be included in the model.

ISSN:1754-5692    

DOI:10.1093/ee/24.4.771

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Obscure scale,Melanaspis obscura(Comstock), is native to the eastern half of the United States where it is associated with hosts in the generaQuercus, Carya, andCastanea. In its native home, the scale is exploited by a complex of natural enemies, including predators, parasites, and pathogens. Although obscure scale is generally maintained at low levels in natural habitats (presumably by natural enemies), it is a major pest of pin oak in urban areas and a minor pest of pecan. In 1962, an infestation of obscure scale was detected on oaks in Capitol Park in Sacramento, CA; efforts to eradicate the infestation were not successful, and this population became a target for classical biological control in 1981. Because the infestation was restricted and spread slowly, there was sufficient time for preintroductory investigations. Exploration for candidate natural enemies for importation into California was directed at parasites associated with obscure scale on pecan in southern Texas. Eleven species in 8 genera were recovered; the major species wereAhlerus clisiocampae(Ashmead),Coccophagoides fuscipennis(Girault),Encarsia aurantii(Howard), andPhyscus varicomis(Howard). Instead of releasing all of the major primary parasites (empirical approach), a moreexperimentalapproach was employed-that is, single-species release ofE. aurantii. This species was chosen because of its thelyotokous reproduction, high egg load at emergence (highest among major primary parasites), and abundance in the native home of obscure scale. Over 11,000 females were released in 1988 and establishment was confirmed in 1990. From 1992–1994, the parasite population increased steadily while the abundance of scale crawlers declined by 3-fold; the crawler-to-parasite ratio declined from ≍25 to ≍7. Through selective pruning, parasitization byE. aurantii, and timing of insecticide treatments, obscure scale is now under integrated pest management (IPM) in Capitol Park, and it may eventually come under complete biological control. This project illustrates how preintroductory investigations both in the native home of the target pest and under quarantine conditions can be used to derive an introduction strategy in classical biological control. Some additional aspects of introduction strategy are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/24.4.779

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

A faunal survey was conducted to find possible biological control agents forParlhenium hysterophorusL. (Asteraceae),a serious annual weed in many parts of the world, particularly Queensland, Australia, and India. Between 1977 and 1991, most of the plant's native range in North America was surveyed from bases at Monterrey and Cuernavaca, Mexico, and Temple, TX. Two hundred and sixty-two phytophagous arthropod species were collected onP. hysterophorusby various methods including hand picking, dissection, rearing, and sweeping; 144 of these species were found to feed on the plant at some stage of their life cycle. The orders represented most abundantly were Coleoptera (33.2%), Homoptera (22.9%), Lepidoptera (20.2%), and Hemiptera (18.3%). Two fungal pathogens, Puccinia abrupta Dietel and Holway varietypartheniicola(Jackson)Parmelee andPuccinia melampodiiDïeteland Holway, were also observed. An index of similarity was used to make pairwise comparisons between the phytophagous arthropod communities on different plant taxa. These comparisons showed that the fauna ofP. hysterophorusis most similar to that of ragweeds (Ambrosiaspp.). Six insect species that were shown to be stenophagous were shipped to Australia for further testing and possible field release. One of the fungal pathogens underwent host-range testing in the United Kingdom and was released in Australia

ISSN:1754-5692    

DOI:10.1093/ee/24.4.796

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Attraction to 3 pest tephritid parakairomone lures (methyl eugenol, trimedlure, and cuelure) of aquatic insects associated with swift-water habitat in representative Hawaiian stream systems is evaluated. Results indicate no attractancy of aquatic insects to methyl eugenol or cuelure. Attractancy is suggested for Hawaiian Orthocladiinae (Diptera: Chironomidae) to trimedlure; however, significant negative effects to stream insect communities are unlikely because total captures were low and likely limited to this family. High variability in aquatic insect response, both within and between streams as well as possible susceptibility to bucket traps suggest that weak-acting lures such as trimedlure are influenced by multiple variables (trap type and placement, season, insect phenology, population characteristics and dynamics, and stream ecotype)

ISSN:1754-5692    

DOI:10.1093/ee/24.4.810

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Field experiments that limited access to carrion bySolenopsis invictaBuren, the red imported fire ant, were used to determine effects of invasion by fire ants on invertebrate carrion decomposers under conditions of scarce and abundant resources. Under conditions of scarce resources, fire ants drastically altered both community composition and the process of succession within the decomposer community. Under conditions of abundant resources, fire ants significantly altered population levels of Calliphoridae, Muscidae, Sarcophagidae, Staphylidae, Silphidae, and Histeridae. Furtthermore, the presence of fire ants altered the patterns of succession as shown by the temporal shifts in total number of larvae. The ecological significance of these changes were examined in the context of equilibrium and nonequilibrium theories of community composition.

ISSN:1754-5692    

DOI:10.1093/ee/24.4.817

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

As part of an investigation to estimate the effect of resident spider populations onErythroneura variabilisBeamer, spider species composition, relative abundance, and seasonal occurrence were determined. Spiders were sampled monthly during the 1992 and 1993 growing seasons; their numbers were pooled and analyzed for species diversity using the Renkonen index of similarity and cluster analysis. Twenty-seven species of spiders were recorded, representing 14 families. The most common species wereCheiracanthium inclusum(Hentz),Trachelas pacificus(Chamberlin and Ivie),Theridion dilutumLevi,Theridion melanurumHahn,Oxyopes scalarisHentz,Oxyopes salticusHentz,Hololena nedraChamberlin and Ivie, andMetaphidippus vitis(Cockerell). Three species (C. inclusum,T. dilutum, andT. melanurum) constituted>30% of all spiders collected; however, species diversity varied among vineyard sites. In 4 vineyard sites, hunting spiders (C. inclusum,T. pacificus,Oxyopesspp., andM. vitis) dominated the fauna, representing an average of 79.7% of the specimens collected. In the other 3 vineyards, hunting and web-weaving spiders were more equally represented, averaging 43.5 and 50.0%, respectively, of all spiders collected. Species similarity between vineyards from both years ranged from 19 to 73% based on the Renkonen index. Similarly, cluster analysis showed a wide separation in species composition among sampled vineyards. The discrepancy in species similarity among sampled vineyards is discussed in reference to potential prey density and vineyard cultural practices. Seasonal abundance patterns of the 8 most common species are presented and discussed in reference to their respective phenologies.

ISSN:1754-5692    

DOI:10.1093/ee/24.4.823

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Larval collections of European corn borer,Ostrinia nubilalis(Hübner),were made in and surrounding a seed corn nursery at Johnstown, ND, a year before and each of 3 yr during a test for hybrid resistance to this insect. Johnstown is in an area known to maintain a univoltine population ofO. nubilalis. The 30,000 inbred corn plants tested for resistance, however, were infested each year with a bivoltine population ofO. nubilalis. Each sample site collection was maintained as a separate population, and the 2nd laboratory-reared generation was tested for diapause frequency in growth chambers programmed to force most univoltine individuals to enter larval diapause and allow a minimum of 50% of bivoltine individuals to continue development. These results illustrate that bivoltine populations dispersed at least 32 km/yr. The results indicate further that light southerly or easterly surface winds (under 8 km/h) were the essential transport mechanisms for this dispersal. It is probable that bivoltineO. nubilalishave been invading the historically univoltine areas of northwestern Minnesota, North Dakota, and the Canadian prairie provinces from the south for years.

ISSN:1754-5692    

DOI:10.1093/ee/24.4.835

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Life-history parameters ofMononychellus progresivusDoreste andOligonychus gossypii(Zacher), 2 major mite pests of cassava in Africa, were determined in the laboratory at 3 constant relative humidities (30, 60, and 90% RH) obtained with saturated salt solutions. Experiments were carried out in airtight boxes placed in an air-conditioned room at 26 ± 1°C and a photoperiod of 12:12 (L:D) h (illuminance 3,500 lux). Low (30% HH) and high (90% RH) air humidity had a negative effect on the life-history traits of both species compared with medium air humidity (60% RH). For both species, the strongest effect was obtained at 90% RH; e.g., noM. progresivuseggs hatched, and 96% of the immature stages ofO. gossypiidied. Relative humidity is, thus, an important abiotic factor influencing the population dynamics of both species and may explain part of the decrease in populations observed in the middle to the end of the dry season and the virtual absence of mites during the wet season.

ISSN:1754-5692    

DOI:10.1093/ee/24.4.841

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Three single-copy sequences from the malaria vectorAnopheles gambiaeGiles are described. For each clone, a restriction enzyme site map, a genomic Southern analysis, and localization to polytene chromosomes are presented. Two clones revealed restriction site fragment polymorphisms, whereas another showed no variation within the strains tested. A portion of 1 clone was sequenced, but showed no significant homology to other sequences in GenBank. The sequence is available in GenBank as accession number L11314. The clones mark chromosome arms 2L, 2R, and 3L.

ISSN:1754-5692    

DOI:10.1093/ee/24.4.846

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Studies were conducted to develop technologies to observe movement behavior, within range of visual observation (≤100 m above ground level), of newly emergedHelicoverpa zea(Boddie) adults and to describe the flight behavior of moths from 6 age or previous activity categories. Moths were released and tracked using a 4-wheel all terrain vehicle, night vision equipment, and auxiliary infrared lighting. Movement, flight behavior, and weather parameters were recorded as moths moved from the take-off site. Observations at Lane, OK, during 1988 indicated that moths tracked on the night after emergence were observable longer than other moth categories. Moths released 1 and 2 nights after emergence were lost primarily because of altitude (>100 m above ground level). Shortly after take-off, moths exhibited spiral flight up to a mean altitude of ≍50 m, and female moths ascended at a sharper angle and faster than males. Subsequently, the angle and rate of ascent decreased and relatively straight, more oriented flight was assumed. Differences in means of observed moth and calculated moth velocity indicated moths were heading crosswise or even into the wind to counter drift (crabbing) during flight. The moths crabbed positively (mean = 8l.8 ± 18.4) to east-northeast winds on 1 night and negatively (mean = −134.2 ± 19.1) to east-southeast winds on another night to obtain a preferred direction to the west. Plots of crab angles with respect to wind speeds suggest that orientation of the moths became increasingly upwind with increasing wind speed. Changes in crab angles with respect to wind speed indicated that there was less variation among crab angles as wind speed increased.

ISSN:1754-5692    

DOI:10.1093/ee/24.4.851

出版商:Oxford University Press    

年代:1995

数据来源: OUP