摘要:

Oviposition, egg viability, and larval longevity forBoophilus microplus(Canestrini) were observed in four field environments and the laboratory. Field environments were shaded woods and unshaded grass areas at Boqueron and Cabo Rojo, Puerto Rico. Annual rainfall is 750–1,250 mm in Boqueron and 1,250–1,850 mm in Cabo Rojo. Relative humidity of the soil surface and temperature were measured. The Weibull cumulative distribution function was used to express egg incubation and larval longevity for the field environments. In the Boqueron woods and the Cabo Rojo grass and woods environment, oviposition and egg viability were similar. Mean period of survival off the host from female engorgement and detachment to larval death in the Boqueron grass and woods and Cabo Rojo grass and woods was 82, 102, 108, and 111 d, respectively. In extreme temperature and relative humidity of Boqueron grass, oviposition, egg viability, and larval longevity were reduced.

ISSN:1754-5692    

DOI:10.1093/ee/19.1.66

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Suitability of annual and perennial species ofSorghum, Lolium, andPanicumand of healthy or maize chlorotic dwarf virus (MCDV)-infected maize (Zea maysL.) was determined for oviposition and development ofGraminella nigrifrons(Forbes). Intra- and intergeneric comparisons show that host life history and genus had a significant effect on the number of adult leafhoppers produced, their weight, and their developmental time from egg to adult, as did the interaction of these effects. More and heavier adults were produced on annualSorghumandPanicumthan on their perennial counterparts. Numbers and weights of leafhoppers produced on annual and perennialLoliumwere not significantly different. Developmental time from egg to adult was shorter on annual than on perennialPanicumbut was not different withinSorghumandLolium. Numbers of adults and their weights onSorghumspecies were greater than onLoliumspecies, which was greater than onPanicumspecies. Evidence that annual grasses may be superior to perennials as hosts within a genus for this generalist leafhopper is consistent with recent studies of natural grasslands that show higher leafhopper densities on annuals during the logarithmic phase of plant growth than at any time on perennials. Although healthy maize was an excellent host forG. nigrifrons, MCDV infection improved its suitability. This agrees with previous field (but not laboratory) studies that show young maize to be a suitable host for this leafhopper.

ISSN:1754-5692    

DOI:10.1093/ee/19.1.76

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Temperature and moisture relations for conidial sporulation and germination ofEntomophaga maimaiga, an Asian fungal pathogen of gypsy moth,Lymantria dispar(L.), were studied in the laboratory. Germination and sporulation occurred between 2 and 25°C with maximal rates between 20 and 25°C. In 50% of cadavers incubated at 20°C, sporulation began within 17.0 h of the hosts' deaths. Spore production and release readily occurred at 95–100% RH, but only limited spore production was seen at 70% RH, and very few spores were produced or released at 50% RH. Germination was delayed by constant light compared with a rapid response under dark conditions: at 20°C, 50% germination occurred in 3.4 h in the dark, but 9.0 h were required in the light. Conidia required free water for germination. Conidiophores did not develop with constant exposure to 30°C. Conidia could survive relatively short exposures to 30°C;>85% of conidia survived ≤6 h of exposure to 30°C.E. maimaigaprotoplasts inside infected insects were more resistant to higher temperatures:E. maimaigacompleted development in 30% of cadavers despite an exposure period of 48 h at 30°C.

ISSN:1754-5692    

DOI:10.1093/ee/19.1.85

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

A loblolly pine mealybug,Oracella acuta(Lobdell), had four to five generations per year in loblolly pine (Pinus taedaL.) seed orchards in southern Georgia. Crawlers overwintered between the needles in the fascicles or under old resin cells made by females of previous generations. Males of the overwintering generation were usually apterous, whereas males of subsequent generations were alate. Population densities did not usually differ significantly between crown levels. Populations in orchards fluctuated; these cycles were apparently caused in part by the adverse effects of aerial insecticide applications on natural enemies, a major factor in mealybug population declines. The two most abundant parasitoids were an encyrtid,Acerophagus coccoisE. Smith, and a platygastrid,Allotropasp.

ISSN:1754-5692    

DOI:10.1093/ee/19.1.99

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Visits byEdovum puttleriGrissell to Colorado potato beetle egg masses on potato plants in field cages were most frequent between 1100 and 1600 hours, 6–11 h after sunrise. In the laboratory at 26 ± l°C, 16:8 (L:D) photoperiod, peak oviposition occurred during the 4-h period between 1400 and 1800 hours, 8–12 h after the lights were turned on. No eggs were laid during the scotophase.

ISSN:1754-5692    

DOI:10.1093/ee/19.1.104

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Regression equations for estimating fecundity of gypsy moth,Lymantria dispar(L.), from egg mass length were compared for a North American population and one from Sardinia, Italy. There was no significant difference in slopes and intercepts of the two data sets, indicating that the relationship between egg mass length and fecundity was the same for these two populations. A combined linear regression function was developed (log10number of eggs per mass = 1.48 log10, egg mass length + 0.44,r2= 0.71,P<0.0001). If subsequent comparisons of this regression with data from other populations reveal the same general relationship, measurement of egg mass length may be of general use as a simple, rapid, noninvasive field estimator of gypsy moth fecundity.

ISSN:1754-5692    

DOI:10.1093/ee/19.1.108

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The effect of larval age on the progress of epizootics of a granulosis virus was examined in field populations of imported cabbageworm,Artogeia rapae(L.), in 1985 and 1986. An enzyme-linked immunosorbent assay (ELISA) was used to follow the progress of disease in three larval age classes beginning 2–3 d after treatment. On virus-treated cabbage, late second and early third instars were more liable to infection than were first and final instars. In laboratory experiments, potted cabbage plants were treated with virus in the same way that field plots had been, and leaves were fed to three age classes of larvae at three temperatures for 18–23 h. Fewer larvae developed disease when given access to leaves at 16°C than at 22 or 28°C. Fewer first instars became infected than third and fifth instars. Third instars were most likely to become infected at all temperatures. The data suggest that virus should be directed at second and third instars rather than at larvae at hatching.

ISSN:1754-5692    

DOI:10.1093/ee/19.1.111

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The phenology of flight and walking movements ofLeptinotarsa decemlineata(Say) adults was studied in a potato field in western Massachusetts using windowpane and pitfall traps. There were two periods of flight activity concurrent with postdiapause and appearance of first-generation adults in the field, and three periods of walking activity concurrent with postdiapause and appearance of first- and second-generation adults. Second-generation adults did not fly. We observed three distinct flight behaviors: local flight in and around the study field, long-distance flight that removed the beetle from the habitat, and diapause flight to nearby woods. Use of rubidium chloride as a marking agent allowed us to determine the origin of adults collected in the windowpane traps. The traps detected mostly local flight activity and were inefficient at monitoring migratory flights. A study in which first-generation adults were netted while they initiated long-distance flight on 24 July and 11 August 1987 revealed two distinct flight behaviors: the first group fed and oviposited after being captured and the second group did not feed or oviposit but entered diapause. We suggest that adults that emerge in July engage in aseasonal migration, which is a regular part of their life cycle, whereas adults that emerge later exhibit diapause-mediated seasonal migration, which is in response to diapause-inducing conditions.

ISSN:1754-5692    

DOI:10.1093/ee/19.1.117

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The age structure, reproductive status, and sex ratio of migrating and dispersing adults ofLepiinotarsa decemlineata(Say) in a potato field in western Massachusetts was determined. Movement by flight (local and migratory) occurred predominantly in adults 7–13 d old. Although significantly more males engaged in local flight activity, possibly in search of mates, males and females were equally likely to migrate by flight. The majority of postdiapause females (73.3%)subsampled from windowpane trap collections reproduced. Only 38.9%(1985) and 44.4%(1986) of first-generation females oviposited, and 89.5%(1985) and 67.7% (1986) of the females that did not oviposit were collected after the first part of August; this was explained by induction of diapause. The applicability of current migration theory to the Colorado potato beetle and the role of migration in the life history strategy of this insect are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/19.1.123

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The gall waspTrichilogaster acaciaelongifoliaeFroggatt (Pteromalidae) was released at 136 sites throughout the distribution area of the weedAcacia longifolia(Andrews) Willdenow in the Cape Province and Natal, South Africa. Each site was monitored annually to determine whether the wasp would establish and to determine its effectiveness where it had established.T. acaciaelongifoliaedid establish throughout the range ofA. longifolia. In the cooler coastal regions of the southwestern Cape and southern Cape, the wasp established well and levels of infestation were consistently high. However, in the hotter inland valleys and west coast of the southwestern Cape Province, and in Natal, establishment was poor and infestation levels were consistently low. In Australia,A. longifoliaoccurs naturally along the coastal regions of southern Queensland, New South Wales, Victoria, and eastern South Australia. However, theT. acaciaelongifoliaeindividuals released in South Africa originate only from the coastal regions of New South Wales and Victoria, and Tasmania. Climatically, these areas correspond most closely to the regions in which the wasp is most successful in South Africa. The method whereby the insects were released in South Africa, and the methods for evaluating the degree of establishment and subsequent infestation levels at each release site, are described.

ISSN:1754-5692    

DOI:10.1093/ee/19.1.130

出版商:Oxford University Press    

年代:1990

数据来源: OUP