摘要:

Selected life history characteristics ofTrichogrammatoidea bactraeNagaraja, a newly imported egg parasitoid of pink bollworm,Pectinophora gossypiella(Saunders), were studied at constant and fluctuating temperatures, with emphasis on high temperatures typical of desert cotton production areas in Arizona and southern California. Developmental times from egg to adult ranged from 11 to just over 7 d at mean temperatures of 22.5 and 29.5°C, respectively. Development was delayed under fluctuating temperatures with maximums ≥33.5°C. Survivorship was>90% under all but a fluctuating 25/40°C regime. Similar results were found forTrichogramma pretiosumRiley, an established species in the southwestern United States. Mean female longevity ofT. bactraeadults ranged from 138 h at a constant 15°C to 1.5 h at 40°C. Mean fecundity peaked at 25°C(55 progeny per female), but modest fecundity (14–23 progeny per female) was maintained at temperatures from 30–35°C. The majority of eggs oviposited by newly emerged adults within the first 24 h of exposure to hosts were laid in the first 3 h and>90% were laid within 12 h. The 24-h rate of oviposition was a nonlinear function of female age and temperature that was maximal for lO-h-old females at ≍25°C. The time of day that females of equal age were initially exposed to hosts did not significantly affect 24-h oviposition rates.T. bactraeappears well adapted to high temperatures; this environmental factor should not significantly hinder the efficacy of this biological control agent in the field.

ISSN:1754-5692    

DOI:10.1093/ee/22.5.1051

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

The spatial distribution of the woolly apple aphid,Eriosoma lanigerum(Hausmann), in a 41-yr-old apple orchard was analyzed using the negative binomialparameter k, Taylor's power law, and Iwao's regression technique. All three indices indicated a highly aggregated distribution of the aphid in the apple orchard. There was a weak but significant linear relationship between the negative binomial k and the mean density for the individual aphids but not for aphid colonies. Compared with Iwao'sregression, Taylor's power law provided a better description of the relationship between the variance and mean density. Woolly apple aphid occurred on the apple trees mainly as apterous virginoparae throughout the year and showed a preference for the lower part of the canopy and the trunk. At low infestations, the aphid is confined to the trunk and large branches but disperses to establish colonies on twigs or new lateral growths during peak populations. Woolly apple aphid has a limited ability to disperse between trees. Population density appears to increase mainly within trees. The relationship between the proportion of infested trees and mean aphid density was in the form of a rectangular hyperbola with an asymptotic upper limit of 33% infestation level.

ISSN:1754-5692    

DOI:10.1093/ee/22.5.1060

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Outbreaks of the gypsy moth,Lymantria dispar(L.), typically occur over large areas but are difficult to predict. Previously developed models forecast defoliation from preseason counts of egg masses in a given stand. In this study, we take a different approach to defoliation prediction: forecasts are based upon the statistical autocorrelation of defoliation through space and time. Spatial and temporal autocorrelation of defoliation in historical data was quantified at a variety of scales using variograms. We used a 30-yr time series of aerial sketch maps of gypsy moth defoliation in Massachusetts to calculate these variograms. The variograms were then used to parameterize a geostatistical estimation technique: three-dimensional simple kriging. Kriged estimates are weighed averages of values from nearby locations and are typically used to interpolate two-dimensional data. In this study, we used kriging to extrapolate future defoliation maps into a third dimension, time. Kriged estimates were expressed as probabilities of detectable defoliation. Predicted probabilities were estimated for each year of the time series and were compared with actual defoliation maps for that year. The kriging procedure usually performed well in predicting the spatial distribution of outbreaks in a given year, but the magnitude of regionwide outbreaks generally lagged a year behind actual values. Though this approachis not currently suitable for operational use, it represents a novel approach to landscape level forecasting of insect outbreaks. These models may ultimately outperform current forecasting systems.

ISSN:1754-5692    

DOI:10.1093/ee/22.5.1066

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Effects of intercropping common bean,Phaseolus vulgarisL., with maize,Zea maysL., at four plant populations on the pod borersMaruca testulalisGeyer andHeliothis armigeraHübner on common bean were studied. The incidence ofM. testulalisandH. armigeralarvae was significantly (P<0.05) lower in intercropped and higher plant populations than in pure stands and lower plant populations of common bean; larval populations ofM. testulalisincreased 45–59 d after planting, followed by a decrease up to 66 d after planting. Percentages of damage to flowers and pods by larvae of the two pod borer species were significantly (P<0.05) lower in an intercrop combination of one-third bean-two-thirds maize (BMM) than in pure bean (BBB). Flower and pod damage decreased when plant populations increased from 66,666 to 1,333,333 plants per ha. The relationship of intercrop combinations and individual plant populations to incidence and damage by pod borer larvae was established by exponential and power regression models. Seed yields of intercrop combinations of BBM and BMM were higher than those of the two crops when grown in monoculture at 133,333 and 266,666 plants per ha. ‘Relative yield total’ thus indicated yield advantages of 16–29% for plant populations of 133,333 plants per ha in both BBM and BMM intercrop combinations, which was associated with lower incidence and damage by pod borer species. Intercropping beans with maize was considered useful as a cultural method for controlling pod borers on common beans and for higher seed yield of the two crops.

ISSN:1754-5692    

DOI:10.1093/ee/22.5.1076

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

A pilot test was conducted in small mountain valleys from 1986 through 1990 in western North Carolina to assess the influence of released, substerilized males on wild populations ofHelicoverpa zea(Boddie), and to measure the level of inherited sterility in wild populations. The number of wild males captured per ha was positively correlated with the distance from the release site of irradiated males. Analyses of seasonal population curves of wildH. zeamales calculated from mark-recapture data suggest that seasonal increases of wildH. zeamales were significantly delayed or reduced (or both) in mountain valleys where irradiated males were released. The incidence of larvae with chromosomal aberrations (progeny of irradiated, released males) collected from the testsites during the growing seasons indicated that irradiated males were competitive with wild males in mating with wild females, and were successful in producing F1progeny which further reduced the wild population.

ISSN:1754-5692    

DOI:10.1093/ee/22.5.1084

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Egg diapause and response of the froghopperAeneolamia varia(F.) to dry conditions were studied in the laboratory. Eggs were obtained from adult females collected in the field in each of fourA. variagenerations. Three discrete groups of eggs were found: nondiapause, short-time diapause, and prolonged diapause eggs with an average time of development of 15.5, 79.2, and 196.2 d, respectively. In generation I, nondiapause eggs accounted for 76.0% of the hatch, but in generation 2, only 19.3%. Prolonged and short-time diapause eggs predominated in generations 3 and 4, constituting 76.7 and 72.0%, respectively. Most of the eggs produced by adult females of generations 2–4 strongly resisted dry conditions. In the field, most of theA. variaeggs were killed by natural enemies or high temperatures (or both) at the soil surface, and only a few survived to hatch between 15 and 123 d. The predominance of nondiapause eggs early in the rainy season allows for a rapid increase in population. Most short-time and prolonged diapause eggs are laid later. This suggests that for control of this pest in sugar cane, insecticide sprays should be applied from the time of the appearance of the first population of nymphs until the development of those that give rise to adults of the generation 2.

ISSN:1754-5692    

DOI:10.1093/ee/22.5.1092

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Odor-mediated behavioral response to permethrin formulations was investigated for two populations (Celeryville, OH, and Geneva, NY)of the diamondback moth,Plutella xylostella(L.). In three-choice olfactory assays, odors from formulations containing 1% or more Ambush or Ambush Blank were significantly avoided by third instars from both populations. The repellent effect was not significant when the concentrations were 0.1% or less. However, 0.01% Ambush Blank was significantly attractive for both populations. Two-choice olfactory assays confirmed the repellent effects of Ambush and Ambush Blank and also showed that 1% Pounce wettable powder formulation was significantly repellent. Technical permethrin did not significantly affect the distribution of larvae from either population. Analyses of how quickly larvae left the arena in the two-choice assays revealed that the permethrin formulations were affecting the speed of larval movement. Larvae moving away from Ambush and, in the case of Celeryville, Ambush Blank, were significantly slower to leave the arena than larvae in corresponding controls. On the other hand, Celeryville larvae that moved toward Pounce wettable powder and larvae from either population that moved toward technical permethrin odors left the test arena significantly more quickly than larvae in corresponding controls. This study indicates that odors from both the active and inert components of permethrin formulations affect larval behavior in ways that could increase the probability of survival in a treated area. Furthermore, contact with deposits is not necessary to elicit these behavioral changes.

ISSN:1754-5692    

DOI:10.1093/ee/22.5.1096

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

In 1990 and 1991 the Biovac, a tractor-propelled vacuum device, was tested to control tarnished plant bug,Lygus lineolaris(Palisot de Beauvois), populations in a strawberry (‘Bounty’) plantation located at Ste-Anne de la Pérade, Quebec, Canada. Two treatments were made in a complete randomized design comprising four replicates:(1) Biovac treatments and (2) control plots (water only). Tarnished plant bug populations were assessed weekly by the saucer pot method. Treatments were done when tarnished plant bug populations exceeded 12 nymphs + adults per 100 taps in the four replicates. Tarnished plant bug populations exceeded the action thresholds six and nine times in 1990 and 1991, respectively. After vacuum treatments, significant tarnished plant bug population reductions occurred 7 times out of 15. On three occasions, populations levels were reduced, but not significantly. Failures occurred 5 times out of 15occasions. There were no significant differences in the percentage of berries attacked by the tarnished plant bug. The use of vacuum devices is discussed in an integrated pest management context.

ISSN:1754-5692    

DOI:10.1093/ee/22.5.1103

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Numbers ofKorscheltellus gracilis(Grote) adults caught on sticky traps are compared between: east and west aspects of Camels Hump Mountain, open canopy gaps and mature conifer stands at 1,000 m elevation, and within dense conifer stands, glades, and glade edges. Numbers trapped were significantly higher on the west aspect and in mature open understory conifer stands. More moths were trapped in glades and along glade edges than in dense conifer stands. Males were caught most often at ground level in dense conifers, at 1 and 2 m height in glades, and at 1 m on glade edges. We suggest that males fly through glades and small gaps searching for female pheromone plumes, and mated females deposit their eggs while perching between short flights.

ISSN:1754-5692    

DOI:10.1093/ee/22.5.1108

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Foraging populations of colonies of the eastern subterranean termite,Reticulitermes flavipes(Kollar), were surveyed in residential and undeveloped environments of southeastern Florida. A triple mark-recapture program using the dye marker Nile Blue A indicated foraging populations ofR. flavipescontain ≍0.2–5.0 million termites per colony, and the foraging territories encompass an area of up to 2,361 m2and a linear foraging distance of 71 m. Habitat type was not correlated with foraging population size.

ISSN:1754-5692    

DOI:10.1093/ee/22.5.1113

出版商:Oxford University Press    

年代:1993

数据来源: OUP