摘要:

Sorghum midge,Contarinia sorghicola(Coquillett) diapause was terminated in the laboratory, and factors affecting adult emergence from diapausing larvae were investigated. Temperatures in the range from 20 to 30°C were optimum for diapause termination and adult emergence. Diapausing larvae exposed to moist conditions at 30°C began to emerge as adults after 12 days of incubation. Based on adult emergence rates per day, an emergence threshold temperature was estimated to be 14.8°C. Exposure to 12 to 13 days of continuous moisture at 30°C was essential for diapause termination and adult emergence. Moisture acted to initiate diapause termination, but diapausing larvae were unable to accumulate shorter periods of moisture toward the 12- to 13-day requirement. Photoperiod had no significant effect on the termination of larval diapause.

ISSN:0046-225X    

DOI:10.1093/ee/12.4.1064

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Forty-nine species of Carabidae were collected from 10 alfalfa fields in Rockbridge County, Va. Species composition and diversity of carabid populations were affected by insecticides applied to control the alfalfa weevil,Hypera postica(Gyllenhal) (Coleoptera: Curculionidae)Harpalus pensylvanicusDeGeer (Coleoptera: Carabidae), a species known to feed on diapausing forms of the alfalfa weevil parasite,Bathyplectes curculionis(Thomson) (Hymenoptera: Ichneumonidae), and on adult alfalfa weevils was more abundant in untreated alfalfa fields than in fields treated with insecticides. A positive relationship was found between densities of adultH. pensylvanicusand damagedBathyplectesspp. cocoons.

ISSN:0046-225X    

DOI:10.1093/ee/12.4.1068

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

An evaluation of the ability of the predaceous speciesToxorhynchites amboinensis(Doleschall) to locate and oviposit in artificial containers in an urban environment was conducted in New Orleans, La. Liberations of laboratory-reared males and gravid females resulted in oviposition in virtually every type of container found in such a habitat; casual observation indicated that oviposition was largely independent of the color and the location of the container with respect to vegetation and buildings. Between May and October, an index of the fecundity, the duration of oviposition after a release, and the proportion of containers that were positive for prey larvae that were also found by predator females declined with decreasing number of females released and with the date of release. Evidence is presented that indicates that the predator females oviposit in response to cues correlated with the presence of prey immatures and that ephemeral habitats such as containers that tend to dry out are less attractive as oviposition sites.

ISSN:0046-225X    

DOI:10.1093/ee/12.4.1073

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Emergence of overwintered sorghum midges,Contarinia sorghicola(Coquillett), was monitored during 1979, 1980, and 1981. Differences in emergence times and distributions among years was a function of soil temperature and rainfall. A heat unit accumulation model incorporating a rainfall adjustment factor was developed which described adult emergence in the spring. Adult midges initiated emergence after accumulating 431 centigrade heat units (based on mean daily 10-cm soil temperatures starting 1 April) above a threshold temperature of 14.8°C, whereas, 679 and 977 heat units were required for 50 and 95% emergence, respectively. Sorghum midges that overwintered in johnsongrass spikelets emerged after similar heat unit accumulations as midges that overwintered in sorghum spikelets. The time that midges initiated diapause one year had little effect on the timing or distribution of emergence the following spring. No midges terminated diapause and emerged as adults during the same season that diapause was initiated. Of the diapausing midges, 23% failed to emerge until the second spring and 2.6% emerged the third spring, but times and distributions of emergence were similar for all years.

ISSN:0046-225X    

DOI:10.1093/ee/12.4.1078

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

SixMedicagoL. species were evaluated in a no-choice oviposition test for the alfalfa blotch leafminer (ABL),Agromyza frontella(Rondani). TheMedicagospecies consisted of the annual diploidsM. disciformisDeCandolle andM. blancheanaBoissier; the annual tetraploidsM. rugosaDesrousseaux,M. noeanaBoissier, andM. scutellata(L.) Miller; and the perennial tetraploidM. sativaL. var. ‘Arc’. More eggs were laid onM. sativaleaflets than on the otherMedicagoentries. ABL preferred to oviposit on nonglandular-hairedMedicagoentries. Density and pinholes, numbers of simple, glandular, and procumbent glandular hairs, and area of the leaflets were measured for each species entry and analyzed by multiple-regression techniques to determine their importance in ABL oviposition. Density of glandular hairs appeared to affect ABL oviposition the greatest. The regression model, however, did not account for the total egg variation in this preference test (R2= 0.31).

ISSN:0046-225X    

DOI:10.1093/ee/12.4.1083

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

The occurrence ofCoquillettidia perturbans(Walker) in subtropical Florida was monitored for 3 years by larval sampling and emergence trapping. Emergence was nearly continuous between mid-March and early November, but not detected at other times. Peaks of adults in mid-June and early September suggested the occurrence of two overlapping generations. Larvae attached to cattail roots overwintered in the 3rd and 4th instars. Larval densities were higher in late autumn and winter than in summer, were negatively correlated with water temperatures, and were positively correlated with average age (instar)of samples. The number of larvae per cattail and root weight were positively correlated. Approximately 50% of larvae detached during uprooting.

ISSN:0046-225X    

DOI:10.1093/ee/12.4.1087

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Studies to examine the relationship between Banks grass mite densities and physiological changes of maturing sorghum plants were conducted. Cytoplasmic male-sterile and male-sterile-producing sorghum lines were used to create different levels of leaf nitrogen, phosphorus, and carbohydrates by manipulating seed set. Higher nitrogen and carbohydrate concentrations were present in sterile plants, whereas phosphorous levels were influenced more by sorghum variety. Only soluble sugar concentration was significantly related to mite densities throughout the grain filling period, with carbohydrates having a negative influence on the mites. Spider mite response to nitrogen and phosphorus concentrations were dependent upon plant phenology.

ISSN:0046-225X    

DOI:10.1093/ee/12.4.1094

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Average daily rates of grasshopper survival were inversely related to density. For a hypothetical population ofMelanoplus sanguinipes(F.), average survival rates of about 0.95 to 0.96 per day resulted in relatively uniform populations between generations; rates slightly above or below that range lead to drastic increases or decreases, respectively. There are reasonable combinations of daily survival rates and daily feeding rates that will allow any developmental stage within a generation of grasshoppers in the field to dominate utilization of forage by that generation. It is most probable, however, that the first three nymphal instars will be responsible for about 15 to 20% of the total forage utilization, and that adults will be responsible for both the greatest daily rate and the greatest proportion of utilization. Utilization by a nymphal instar is likely to exceed that of adults only under conditions of catastrophic population collapse.

ISSN:0046-225X    

DOI:10.1093/ee/12.4.1099

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Field studies indicated thatApanteles yakutatensiswas a relatively common parasite ofAutographa californicaon peppermint. Adult parasites were active throughout much of the growing season (June through September) and were present at all locations sampled. Parasitism byA. yakutatensiswithin individual samples of field-collected 3rd- and 4th-instar hosts ranged from 7 to 71%. LarvalA. yakutatensisdevelop as gregarious endoparasites in 2nd- to 5th-instar hosts. An average of 29 parasites emerged per host with a highly variable sex ratio, generally 4:1. A hyperparasitoid,Stichtopithussp., was observed to be rare.

ISSN:0046-225X    

DOI:10.1093/ee/12.4.1103

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Atmospheric electric fields, believed to influence various biological phenomena, are monitored by using an instrument called a field mill. Previously published field mill designs were determined to be unsatisfactory for entomological research. The design described herein is specifically intended for biological research at remote locations and includes two design innovations—a perforated circular rotor and a dc power supply.

ISSN:0046-225X    

DOI:10.1093/ee/12.4.1107

出版商:Oxford University Press    

年代:1983

数据来源: OUP