摘要:

Discrete frequency distributions, obtained from count data onSolenopsis invictaBuren,Aphisspp.,Pseudatomoscelis seriatus(Reuter) adults and nymphs.Orius insidiosus(Say).Nabisspp., andGeocorisspp., in 1973 and 1974, were fitted to seven mathematical frequency distribution models. The negative binomial distribution best described the dispersion pattern of these insects in both years, indicating an aggregated, nonrandom dispersion pattern. The parameter k of the negative binomial distribution was used to quantify the aggregation of these insects. The maximum likelihood estimate and the moment estimate were two methods used to estimate the parameter k. A common k was calculated for each insect studied, to determine whether the estimated k values were common to all sampling dates over a season. As indicated by common k values,Aphisspp. andS. invictawere highly aggregated.P. seriatusnymphs were more aggregated than the adults. Among the predators,Nabisspp. were more aggregated thanO. insidiosus;andGeocorisspp. were the least aggregated. Taylor's power law was fitted to the variance and mean density values for each insect. The power function well described the relation between the variance and mean density value for each insect

ISSN:0046-225X    

DOI:10.1093/ee/12.2.380

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

The maximum parasitism rate byDoryphorophaga doryphorae(Riley) of the Colorado potato beetle (CPB),Leptinotarsa decemlineata(Say), approached 75%. However, this occurred in late August and September, when the CPB larvae had already damaged the crop. The effectiveness of the parasite was limited by its low abundance during the first generation of the CPB. Although 9, 30, and 61% of the 2nd, 3rd, and 4th larval instars of CPB, respectively, were parasitized, parasitic maggots did not develop until the fourth-stage CPB larva entered the soil to pupate. Thus, there was a delay of about 7 days in fly emergence from hosts that had been parasitized as 2nd-instar rather than 4th-instar CPB larvae. We estimated that as much as 39% of the emerging fly were delayed over a 7-day period

ISSN:0046-225X    

DOI:10.1093/ee/12.2.386

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Doryphorophaga doryphorae(Riley) is a parasite of the Colorado potato beetle,Leptinotarsa decemlineata(Say). In our tests, male parasites emerged a few days earlier than females, with a 3:1 numerical advantage in the first 3 days. The female parasite is larviparous and the prelarviposition period averaged 7.8 days. The average larviposition period was 21 days, with the longest period being 45 days. On the average, the female parasite larviposited 215 times in her lifetime and at the rate of 10.8 times per day. When hosts were withheld for a few days and then made available to the flies, the rate of parasitism and superparasitism was substantially higher than normal for a brief period. Under laboratory conditions, the female did parasitize 1st-instar CPB larva, although at a lower rate (3 to 11%) than it did the other larval instars

ISSN:0046-225X    

DOI:10.1093/ee/12.2.390

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Seasonal flights ofOstrinia nubilalis(Hübner) were monitored in 1981, using blacklight traps in 28 locations in central and western New York state. Calendar date of peak catch and heat unit accumulations indicated the presence of both univoltine and bivoltine biotypes, although before this study, only the latter was assumed to be present in these regions. Both biotypes were evident at 16 of the 28 trapping sites. Trap catches during the last 5 years of a 15-year study (1967–1981), at a fixed location near Geneva, N. Y., indicated the recurrence of a univoltine population that had last been noted in this region before 1964. Losses due to larval contamination of processed snap beans are reported for 1979 and 1980. Growers of susceptible crops must be aware of local flights and the potential for shifts in peak moth emergence before insecticides are applied

ISSN:0046-225X    

DOI:10.1093/ee/12.2.393

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

An artificially-induced epizootic was created in European pine sawfly(N. senifer)populations at density levels of 5, 7, and 10 colonies per tree when plots were treated with 3.5 × 108polyhedral inclusion bodies (PIB) per 0.04 ha. The progress of the epizootic was followed daily. The onset of mortality was at 13 days posttreatment, with a peak mortality period between 14 and 16 days across all density situations. During this period, ca. 70% of the total larval mortality was recorded. Of all the larval instars that died, the 4th experienced the greatest percentage of virus-induced mortality (ca. 58%). The average number of PIB accumulated per larva was inversely related to the density situations. That is, larvae in a low-density situation (five colonies per tree) accumulated more virus than those in a moderate-density situation (seven colonies per tree), and similarly between the moderate and high-density situations (10 colonies per tree). This resulted in an inverse relationship between the average number of PIB produced per plot and colony density per tree: 2.92 × 109, 9.00 × 108, and 3.3 × 108, in low-, moderate-, and high-density situations, respectively.

ISSN:0046-225X    

DOI:10.1093/ee/12.2.397

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Seasonal flight of the lilac borer,Podosesia syringae(Harris), was monitored with pheromone traps during 1980–1982, and cumulative emergence was related to physiological time (i.e., degree-days [DD]). A base temperature of 10°C yielded the lowest coefficient of variation for DD summations to first catch, and was therefore selected for use in the linear heat unit system. First capture of lilac borer males in Kentucky ranged from 13 April to 6 May, and corresponded to a mean DD accumulation from 1 January of 168.9 in Lexington and 189.9 in Louisville. Flight in both cities peaked from late May to early June and ended by mid-July. Of three forecasting methods, average DD summations or projected DD requirements from a regression model were more reliable than average calendar dates for predicting optimum treatment dates in Louisville.

ISSN:0046-225X    

DOI:10.1093/ee/12.2.400

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Phytophagous insects representing six orders, 14 families, and 18 identified and 3 unidentified species are reported as comprising the insect fauna of spiny c1otbur,Xanthium spinosumL. (Compositae), in southern California. Similarly, insects representing six orders, 29 families, and 60 species are reported as associates of cocklebur,X. strumariumL. Most insects attacking these introduced weeds were polyphagous, sap or foliage-feeding species. Many also were ragweed,Ambrosiaspp., insects. One-third of the insect species collected from spiny clotbur and 15% of the cocklebur insects were endophagous as immatures. Eighty-three percent and 75% of the 18 and 52 associates identified to species are newly reported from spiny clotbur and cocklebur, respectively. Sixty-one percent and 44% of the identified associates of these two weeds, respectively, were major or minor pests of cultivars. Also. five (24%) and eight (13%) of these identified associates, respectively, were stenophagous species, their hosts apparently confined to the tribe Heliantheae

ISSN:0046-225X    

DOI:10.1093/ee/12.2.404

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Psychoda alternataSay (Diptera: Psychodidae)is reported emerging from sludge-amended agricultural fields, and a simple and efficient method for rearing this insect in the laboratory on liquid digested sewage sludge is described. Mean days from egg to adult emergence at 24°C for males was 11.2 ± 0.24 (n= 45); for females it was 13.1 ± 0.52 (n= 30). An experiment testing ovipositional attractiveness of three sludges of 3.02, 6.38, and 13.81% solids showed a significant preference for the latter. An examination of possible carnivorous tendencies of larvae proved negative

ISSN:0046-225X    

DOI:10.1093/ee/12.2.412

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Adalia bipunctataL. has low developmental thresholds (t) for postdiapause and nondiapause development that adapt it to activity early in the season. Postdiapause reproductive development leading to oviposition requires an accumulation of 87 degree-days (K) above a relatively low developmental threshold temperature (t) of 6.8°C. Overwintering adults disperse and initiate oviposition during early to mid-May. The linearly derived (t) and (K) values of 263 ± 9.0 degree-days above 9.0°C for preimaginal development and daily maximum-minimum temperatures from outdoors accurately predicted outdoor developmental rates. Preimaginal development outdoors during June and July required 269 ± 12 degree-days above 9.0°C under conditions of excess prey. In the field, there are two to three generations per year in the Ithaca, N.Y., area. The critical photoperiod for diapause induction in the Ithaca, N.Y., (~42°N) population lies between LD 13:11 and LD 14:10 (23°C). Short daylengths maintain diapause, and during autumn the duration of diapause is quantitatively related to photoperiod. Diapause completion does not require chilling: during winter-early spring. photoperiod may exert some influence on the timing of diapause termination.

ISSN:0046-225X    

DOI:10.1093/ee/12.2.416

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Easter lily bulbs,Lilium longiflorumThumb. “Nellie White,” from Oregon were grown under controlled temperature forcing in a greenhouse to flower at Easter. Various miticide and fungicide treatments were applied to elucidate the relationship between a bulb mite,Rhizoglyphus robiniClaparède, and root rot control as caused byPythium ultimumTrow andFusarium oxysporumSchl. emend. Snyd. and Hans. Dicofol and aldicarb, regardless of time of application, significantly reducedR. robininumbers. Dicofol also significantly reduced root rot. Tests showed that dicofol had fungicidal as well as miticidal activity. The fungicide combination of benomyl and Truban gave significant root rot control only when mite populations were relatively low. It is concluded that a threshold exists forR. robiniin greenhouse-forced Easter lilies above which mite suppression is necessary for adequate root rot control by fungicides.

ISSN:0046-225X    

DOI:10.1093/ee/12.2.422

出版商:Oxford University Press    

年代:1983

数据来源: OUP