摘要:

The parasitoidBrachymeria ovata(Say) (Hymenoptera: Chalcididae) oviposited and developed in pupae ofPseudoplusia includens(Walker),Trichoplusia ni(Hübner),Heliothis zea(Boddie),Heliothis virescens(F.),Spodoptera exigua(Hübner),S. frugiperda(J. E. Smith), andAnticarsia gemmatalis(Hübner) (all Lepidoptera: Noctuidae), that had been frozen at −20°C for 30–90 d, and thawed for 4–6 h at 27°C prior to exposure. AdultB. ovatawhich developed from these hosts mated and produced fertile offspring. Parasitoids oviposited and developed inA. gemmatalispupae that had been stored at −20°C for as many as 256 d before exposed to parasitoids. In addition, parasitoids developed from freezer-storedA. gemmatalispupae that had been removed from the freezer (−20°C) and held at 27°C for as many as 8 d before exposed to parasitoids. Thus, freezer storage may be a feasible method of obtaining large numbers of hosts for mass rearing ofB. ovata.

ISSN:1754-5692    

DOI:10.1093/ee/16.6.1207

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Direct field observations and use of radioactive phosphorus (32P) as a tracer showed 18 insect and 6 spider species, representing 6 orders and 19 families, to be predators ofNezara viridula(L.) in a soybean ecosystem in Louisiana.Solenopsis invictaBuren was the dominant egg predator during the vegetative stages of soybean development, while cannibalism of eggs by adults and nymphs ofN. viridulawas also frequently observed during this stage. Grasshoppers were the more important egg feeders during the reproductive stages of plant development. Life tables developed forN. viridulain field cages showed that survival to adult was 0.5% during the vegetative and flowering stages and 4.5% during pod set, but it increased significantly to 38.2% when seeds were formed. Under field conditions during the latter period, survival to fourth-instar nymphs declined to 8.7%, from which it was concluded that, in this particular ecosystem, 33.6% mortality was caused by predation and 57.7% was due to other factors.

ISSN:1754-5692    

DOI:10.1093/ee/16.6.1211

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

A low-density population of the Douglas-fir tussock moth,Orgyia pseudotsugata(McDunnough), was studied for 13 yr in a mixed-conifer forest in south central Oregon. The densities of tussock moth and associated mortalities in each life stage were estimated over seven consecutive generations by sampling larvae and artificially stocking egg masses and pupae. A single census of early larvae was made annually for an additional 6 yr. Mortalities were summarized in life tables, converted tok-values, and analyzed to detect key factors, compensatory interactions, and density dependence. The largest losses in each generation were from the disappearance of larvae and the parasitization of eggs. A large, unexplained error was also present in most generations. None of the estimated mortality factors qualified alone as a key factor; however, the combined parasitization of eggs, larvae, and pupae was more closely related to changes in generation mortality than was predation of these stages. Parasitization was also delayed density-dependent, but predation was independent of density over the 7 yr that life-table data were collected. The major mortality factors interacted in a compensatory way, so that their combined effects for the full 13 yr of the study were delayed density-dependent and regulatory. This parasite/predator-prey system with a time lag apparently explains the low-density oscillation of tussock moth abundance.

ISSN:1754-5692    

DOI:10.1093/ee/16.6.1217

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

The microsporidium,Vairimorpha necatrix(Kramer), was evaluated for potential use as a biological control agent for black cutworm,Agrotis ipsilon(Hufnagel), larvae. The LC50ofV. necatrixwas determined for third, fourth, and fifth instars. LC50values increased ca. 10-fold between instars. A grape pomace bait that incorporatedV. necatrixspores was also bioassayed. LC50values for this formulation increased with instars; a 17-fold difference occurred between third- and fifth-instar black cutworms.

ISSN:1754-5692    

DOI:10.1093/ee/16.6.1228

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Healthy adult males of the Indianmeal moth (IMM),Plodia interpunctella(Hübner), were contaminated with a bentonite/granulosis (GV) dust when attracted to the source by a pheromone lure. Surface contamination of males was transferred to adult females during copulation, and larval food was subsequently contaminated by females during oviposition. The F1generation of larvae acquired viral disease. Although several routes of virus transfer from adults to larvae may take place, the most effective transmission occurred when young larvae fed on cadavers of contaminated moths or when only a small quantity of larval food was available for contamination and ingestion. Fifty-two percent of the introduced larvae that fed on GV-contaminated adult male IMM cadavers and 44% that fed on female moths that had been contaminated by males during copulation developed patent virus infections. However, only 12 to 32% of the F1progenies of the GV-contaminated female moths acquired patent infections. Data were highly variable. Results confirmed similar laboratory studies conducted by others withTrogoderma glabrumand the protozoan,Mattesia trogodermae.

ISSN:1754-5692    

DOI:10.1093/ee/16.6.1231

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

In feeding preference tests using either leaf disks or stem sections, higher numbers of stalk borer (SB),Papaipema nehris(Guenée), fed on grasses than on broadleaf plants. Cool-season perennial grasses, such as orchard grass or fescue, were preferred. Feeding preferences did not exhibit a sharp demarcation between acceptable and unacceptable hosts. Degrees of preference were observed as a graded continuum between highly acceptable to less acceptable host plants. A higher percentage of individuals (65.5) chose to wander and did not feed on leaf disks, as compared with the percentage that chose to wander (48.2) when presented stem sections. In no-choice feeding tests on plants in the laboratory, first-instar SB infested plants at the same rate that they damaged plants, showing a tendency to tunnel into acceptable host plants. Annual rye sustained the greatest amount of damage (74%) and had the highest percentage (27) infestation. Using third- or fourth-instar SB in no-choice field cage studies, infestation levels were greatest for orchard grass and annual rye. Damage levels were lowest for red clover and cheat. Larvae recovered from field corn showed preferences for feeding on field corn, as compared with sorghum, orchard grass, and alfalfa.

ISSN:1754-5692    

DOI:10.1093/ee/16.6.1235

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Adult populations of corn earworm,Heliothis zea(Boddie), and fall armyworm,Spodoptera frugiperda(J. E. Smith), were monitored concurrently with pheromone traps and sugarline sampling in sweet corn during 1982–84 in southern Georgia. Numbers of corn earworm and fall armyworm males captured in pheromone traps were usually significantly correlated to numbers of females recorded in sugarline samples. At shorter (daily) sampling intervals, this relationship was stronger. The association between pheromone trap catches of males with the males recorded in sugarline was significant only when the sampling interval was daily.

ISSN:1754-5692    

DOI:10.1093/ee/16.6.1241

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

A numerical trajectory analysis scheme is used to estimate the pathways of insects in the lowest 2 km of the atmosphere during three hypothetical pest migrations. The investigation incorporated winds-aloft data from a series of special meteorological field experiments conducted over the eastern United States during the spring of 1979. Hypothetical pest-catch sites were chosen from which trajectories were constructed upwind (back-trajectories) at seven levels between the surface and 800 mb (ca. 2,000 m). Comparisions were made between 12-h data (the normal operational interval) interpolated to 3 hand 3-h observed data to examine temporal variabilities in the near-surface wind fields. In addition, back-trajectories were constructed with data using only the regular upper air sounding network versus the regular network supplemented with additional sites to explore differences due to increases in the horizontal resolution of the wind. Finally, an intercomparsion study was conducted with several trajectory analysis methods of pest migration studies reported in the literature and the objective procedure described here. Results suggest that increased resolution of the vertical structure of the horizontal wind fields substantially decreases the uncertainties in the estimated paths of migrants. Increases in the temporal and horizontal frequencies of the wind produced differences in back-trajectory endpoints that were 4–5 times smaller than those from the improved vertical resolution. Backtracking methods of previous researchers appeared to provide reasonable approximations of potential source regions for migrants, but only when both surface and upper air data were incorporated into the analysis and with lower-tropospheric airflow conditions that were reasonably homogeneous.

ISSN:1754-5692    

DOI:10.1093/ee/16.6.1244

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Parasitoids are always of major concern in integrated pest management (IPM) programs. However, their use as a control option is handicapped by our lack of understanding of their total life support systems. Because of this, pest managers have, in most cases, only been able to work “around” natural enemies in space and time as opposed to explicitly manipulating their numbers. Manipulation or management of parasitoids is difficult particularly for polyphagous species and for those species whose hosts exhibit a large amount of phenotypic variability. The objectives of this study were to determine the potential effects that phenotypic variability and system complexity can have on parasitism and to suggest ways in which these factors could be used in IPM programs using parasitoids.Data were collected from a natural system composed of the eastern tent caterpillar (ETC), fall webworm (FWW), and a parasitoid (Hyposoter fugitivus fugitivus(Say)) common to both defoliators. Interactions between the ETC, FWW, andH. f. fugitivuswere examined using a simulation model describing the population dynamics of each species. The model was validated using field data including: temporal occurrence, larval population maturity, survival patterns, yearly population trends, and trends in parasitization rates. Sensitivity analyses demonstrated how site-specific conditions, regional host crop and non-host crop mixes, and host population variability could be used in the development and implementation of management programs for parasitoids and pests.

ISSN:1754-5692    

DOI:10.1093/ee/16.6.1255

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Flowering herbaceous plants in the Northern Blackland Prairies of Texas were sampled with a sweepnet in 1982 and 1983. Plant species were classified as nonhosts, feeding hosts, or reproductive hosts of the tarnished plant bug,Lygus lineolaris(Palisot de Beauvois). Reproductive hosts were classified as early-season hosts, hosts supporting insect populations that move into cotton, or hosts providing insects for the next year's populations. Changing agronomic practices and plant succession, resulting in increased abundance of broad-leaved hosts, may be responsible for the increasing seriousness of tarnished plant bug pest status.

ISSN:1754-5692    

DOI:10.1093/ee/16.6.1266

出版商:Oxford University Press    

年代:1987

数据来源: OUP