摘要:

Data were extracted from published information to evaluate the influence of pest feeding niche on the past performance of classical biological control against holometabolous insect pests. Data were tallied and analyzed to account for confounding variables and to minimize potential sources of sampling bias. For the two orders with adequate sample sizes, biological control was much more successful against pest species that feed in relatively exposed locations (i.e., folivores) than against species that feed while deeply concealed within plant tissue or below ground. In the Lepidoptera, partial or better success was achieved against 61% of folivorous species (e.g., free-feeders, leaf rollers, leafminers, etc.) but against only 15% of deeply concealed pests (e.g., borers); in the Coleoptera, success rates were 57 and 22%, respectively. Rates of establishment of introduced parasitoids and the effectiveness of established parasitoids were also greater against exposed than against deeply concealed pests. In addition, importation of ectoparasitoids, a group usually restricted to concealed hosts, was strongly associated with biological control failure. Contrary to expectations, the performance of biological control was not poorer against pests using feeding niches that permit greater mobility. In the Coleoptera, biological control was more successful against pests in types of feeding niches that typically support larger numbers of parasitoid species.

ISSN:1754-5692    

DOI:10.1093/ee/20.5.1217

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Five methods were evaluated for measuring the effects of arthropod pests on crop yields in vegetationally diverse agroecosystems, and the conditions for vegetational diversity to improve yields were examined. Two methods measured absolute yield benefits in which polyculture yields were higher than yields in monocultures. A review of the literature indicated that absolute yield benefits occurred only rarely and only when the arthropod pests caused severe yield losses in monocultures. One method was judged of limited use. The remaining two methods measured marginal yield benefits, in which yield loss in polycultures is less than that in monocultures. Statistical tests for factorial experiments that estimate this marginal benefit are proposed. A review of 41 cases suggested that this benefit occurred only if polycultures had lower pest populations than monocultures, and even then, it occurred intermittently. Severe competition from the other plants in the polyculture might limit the ability of the crop to compensate for pest injury and crop tolerance, or resistance to pest injury might otherwise limit yield losses in polycultures. In addition, the data suggested that pest injury is less likely to exceed economic injury levels in polycultures than in monocultures.

ISSN:1754-5692    

DOI:10.1093/ee/20.5.1228

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Computer-based technologies have greatly advanced insect pest management. However, as their size and complexity have increased, they have become more oriented toward insect management than insect science. Because these technologies consume a significant percentage of entomology's scarce computer expertise, it is important that the advancement of entomology as a science be the point of emphasis. This suggests that changes in priorities are necessary in the areas of research and development at all levels—from the development of farmer-oriented (end user) systems to the individual research entomologist to the funding agency level. This paper presents one perspective on these issues.

ISSN:1754-5692    

DOI:10.1093/ee/20.5.1236

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Recent articles by Perry (1986, J. Econ. Entomol. 79: 1149–1155) and Jones&Matloff (1986, J. Econ. Entomol. 79: 1156–1160) have explored some of the current abuses of statistical hypothesis testing. Jones&Matloff suggest that only estimation, and no statistical hypothesis testing, should be performed. We express the alternative view that there is an inherent relationship in estimation and hypothesis testing and that each provides information which the other does not. We address some of the concerns that have been expressed about statistical hypothesis testing and show how they are present when using estimation. When the goal of sampling is to determine whether an insect population should be controlled chemically, sequential hypothesis testing is preferred to estimation procedures.

ISSN:1754-5692    

DOI:10.1093/ee/20.5.1241

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Scientists must make decisions based on experimental data and often use statistical hypothesis tests, either formally or via P values, as the basis for such decisions. However, these tests are designed for answering questions which are almost never of scientific relevance. This paper demonstrates this problem and discusses specific alternative methods.

ISSN:1754-5692    

DOI:10.1093/ee/20.5.1246

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

We tested two agronomic practices that are likely to increase plant and structural diversity, no-tillage and strip intercropping, for effects on corn invertebrate fauna. Some of the most common herbivores and natural enemies were sampled by direct counts and damage estimation from 1988 through 1990 on monoculture corn and strips of corn alternated with soybean, under no-tillage and conventional tillage. Among soil pests, cutworms (mostly the black cutworm,Agrotis ipsilon(Hufnagel)); armyworm,Pseudaletia unipuncta(Haworth); and slugs (Gastropoda) were more abundant in no-tillage plots, although only slugs caused severe damage. The western corn rootworm,Diabrotica virgifera virgiferaLeConte, and the European corn borer,Ostrinia nubilalis(Hübner), were generally more abundant in conventional tillage plots. Despite crop rotation, the strip-intercropping system (four rows of each crop) was less effective in reducing western corn rootworm infestation, especially in conventional tillage plots. In 1990 only, ladybugs (mostlyColeomegilla maculata(DeGeer)) were more abundant in conventional tillage plots, whereas tarnished plant bugs,Lygus lineolaris(Palisot de Beauvois), were more abundant in notillage plots. Japanese beetle,Popillia japonicaNewman; stink bugs,Acrosternum hilare(Say) andEuschistus servus(Say); and spiders (Aranea) were not significantly affected by treatments.

ISSN:1754-5692    

DOI:10.1093/ee/20.5.1251

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Fall armyworm,Spodoptera frugiperda(J. E. Smith), is an early season production constraint of sorghum,Sorghum bicolor(L.) Moench, and maize,Zea maysL., in Central America. Because fall armyworm populations decline after a brief buildup on landrace sorghum, this study was conducted to determine whether antibiosis was a mechanism of resistance. Three fall armyworm feeding experiments were conducted in the laboratory using whorl-leaf material collected daily from sorghum. Experiments began with neonate larvae once plants had lived for 30–40 d. Mortality, pupal weight, generation time, intrinsic rate of increase (rm), and relative fitness were used to make inferences about antibiosis. Experiment 1 determined that the moderately resistant check, 1821 c.m. (rm= 0.31), was comparable to the susceptible check, ‘Huerin Inta’ (rm= 0.30), thus indicating that its mechanism of resistance was probably larval nonpreference. However, landrace San Bernardo III (rm= 0.27) significantly suppressed fall armyworm population density increase. Experiment 2 confirmed resistance in landrace San Bernardo III and showed that its resistance could be combined with that of inbred line TAM428 to produce an enhanced level of antibiosis. The mechanism of resistance in ‘AF28’ also was shown to be antibiosis. Experiment 3 indicated that antibiosis may be widespread in land race populations and that it was manifested differently than in ‘AF28’. Cohorts raised on three landrace accessions attained significantly lower pupal weights (184–191 mg/larva−1) than those raised on ‘AF28’ (216 mg/larva−1). They also suffered significantly higher mortality on ‘AF28’ (42%) than those raised on landrace populations (16–30%). Antibiosis was detected in the landrace accessions San Bernardo III, Hilate-179, Piña-61, and Lerdo-104. A hypothesis, based on differential selection and increased selection pressure brought about through intercropping with maize, is presented to explain the development of antibiosis in these landrace populations.

ISSN:1754-5692    

DOI:10.1093/ee/20.5.1259

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Seasonal abundance and temporal variation in dispersion patterns of the poplar petiolegall aphid,Pemphigus populitransversusRiley, were examined in serial planting studies of cabbage and broccoli from 1986 to 1988 using variance/mean ratioS2/$\bar x$, Green'sCx, Standardized Morisita'sIp, and Taylor's regression of log variance on log mean. All indices predicted an aggregated dispersion of aphid numbers, with no apparent trends in seasonal variation in dispersion. Values ofβfrom Taylor's regression were homogeneous among cultivars and plantings in 1986–1987, but the slope calculated for aphid dispersion in the September planting differed from theβvalues estimated in October and December plantings in 1987–1988. The estimatedβcalculated from the commercial cabbage field was not different from most of the serial plantings. Alate fundatrigenia began emerging from laboratory-held galls in early July, and peak emergence occurred from October through November. There was a corresponding empirical trend of higher aphid densities in September plantings and progressively less dense populations in the October–December plantings. It is hypothesized that there was differential exposure to aphid colonization among plantings. A pooled estimate ofαandβwere used to determine the number of samples required to obtain an estimate of the mean density ofP. populitransversusin crucifers within 10 and 25% of the true mean. An alternate method of population estimation, using a presence–absence sample, was also presented.

ISSN:1754-5692    

DOI:10.1093/ee/20.5.1267

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

A field cage was used to study sex pheromone mediated behavior and evaluate female-baited pheromone traps for capture of males of the pickleworm,Diaphania nitidalis(Stoll). Males were attracted to females throughout scotophase with peak attraction occurring during the third (2200–2259 hours), fourth (2300–2359 hours), and fifth (0000–0059 hours) hours. Four traps were evaluated: (1) the box, currently used for monitoring pickleworm moth populations; (2) the Heliothis; (3) the Pherocon 1C (sticky); and (4) the unitrap (bucket). The bucket trap consistently captured and retained more male pickleworm moths than the other traps tested. The bucket trap was evaluated at 30, 80, 150, and 180 cm above ground level. Significantly more males were caught at 80 and 150 cm than at either extreme. Trap efficiency was determined for the bucket trap and a modified (Fluon-coated outer cone) bucket trap. Efficiencies for the bucket and modified bucket traps were not significantly different. The bucket trap caught 20.3 ± 1.2% ($\bar x$± SEM) of males orienting toward the trap, 29.3 ± 1.7% of males touching the trap, and 41.0 ± 3.3% of males landing on the caged females used as the pheromone source.

ISSN:1754-5692    

DOI:10.1093/ee/20.5.1274

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The goal of this paper was to examine the premise that lightning is a disturbance to pine forests that occurs with sufficient frequency to provide reliable habitat for the persistence of bark beetles. The study was conducted in the pine forest region of East Texas. Using Texas Forest Service maps, this 55,400-km2area was partitioned into systematically numbered grid cells (5 by 5 min) of latitude and longitude (units ≍64 km2in area). There were 607 cells in the study. Data for the study were collected for the years 1975, 1976, 1977, 1982, and 1983 and consisted of forest cover, bark beetle infestations, and lightning strikes. Cumulative bark beetle herbivory (number of infestations) in relation to cumulative lightning strikes and the rate of change in numbers of bark beetle infestations relative to lightning strikes were examined. In 4 of the 5 yr of the study, cumulative infestations increased as a function of cumulative lightning strikes. As population levels increased (i.e., changed from enzootic to epizootic levels), a greater proportion of lightning-struck hosts were exploited by the bark beetles. At enzootic population levels, refuges in the form of lightning-struck trees were judged to be particularly significant to the persistence of the insects. Conversely, at epizootic population levels, initiation of a substantial portion of the observed infestations was due to factors other than lightning. Examination of the relation of rate of change in infestations relative to cumulative lightning strikes indicated that the availability of lightning-struck hosts for colonization was not a limiting factor in regional landscape epidemiology. Sufficient lightning-struck trees are available for colonization across a range of enzootic to epizootic population levels.

ISSN:1754-5692    

DOI:10.1093/ee/20.5.1279

出版商:Oxford University Press    

年代:1991

数据来源: OUP