摘要:

Paedogenesis (reproduction in the sexually immature stage) was found in 1.8% of alate greenbugs,Schizaphis graminum(Rondani), but the frequency was not increased by selection of progeny resulting from paedogenesis. Insects reproducing by paedogenesis produced an avg 1.7 nymphs in 1.3 days before developing wings. This is the 1st known report of paedogenesis in the family Aphididae.

ISSN:0046-225X    

DOI:10.1093/ee/4.6.1001

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

Three species of aquatic invertebrates, sampled at sites in Lake Michigan, were subjected in the laboratory to known sodium chloride and potassium chloride concentrations in aqueous solutions. Lethal levels for each organism were observed and recorded for periods of 48 h. One hundred percent mortalities for NaCl concentrations were calculated from a regression line to be 3735 mg/liter forNais variabilis(Piguet), 8865 mg/liter forCricotopus trifasciaEdwards, and 10,136 mg/liter forHydroptila angustaRoss. KCl concentrations at 204 mg/liter forN. variabilis, 4896 mg/liter forC. trifascia, and 6317 mg/liter forH. angustawere calculated for the 100/ mortality level. The lethal aspects of these chloride salts are discussed.

ISSN:0046-225X    

DOI:10.1093/ee/4.6.1003

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

Rhyzopertha dominica(F.),Oryzaephilus surinamensis(L.),Tribolium castaneum(Herbst),T. confusumJacquelin duVal,Cryptolestes pusillus(Schönherr),Sitophilus granarius(L.), andS. oryzae(L.) were not appreciably affected by a commercial formulation of Bacillus thuringiensis var.kurstakion wheat or a flour-cornmeal mixture at 100 or 500 mg/kg. However,R. dominica,S. oryzae,T. castaneum, andT. confusumtransferred viable spores from treated to untreated wheat by carrying them externally or passing them with their feces.

ISSN:0046-225X    

DOI:10.1093/ee/4.6.1007

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

The diapausing pupae of the western cherry fruit fly,Rhagoletis indifferensCurran, and its major parasite,Psilussp., were exposed to different temperatures for various lengths of time to determine their susceptibility to extreme cold temperatures. Both the fruit fly and the parasite showed a high degree of tolerance to sub-freezing temperatures. They survived almost all tested (16–48 days) exposures at −4°C, and certain shorter (16–36 days in non-soil and 16–48 days in soil) exposures at −10°C. The exposure of both these groups of insects to −16°C resulted in high mortality (82–100%) and a drastic reduction in adult emergence. Data indicate that temperature fluctuation during winter months might give a reasonable predictive indication of the size of the cherry fruit fly population for the following summer.

ISSN:0046-225X    

DOI:10.1093/ee/4.6.1011

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

The effects of temperature and relative humidity on egg hatching bySynanthedon pictipes(Grote and Robinson) were studied. Of the 15 treatments in the test, the highest percentage of hatched eggs (79.1%) was obtained at 20°C and 73–78% RH.

ISSN:0046-225X    

DOI:10.1093/ee/4.6.1014

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

Overwinter survival and spring emergence patterns of the bollworm,Heliothis zea(Boddie), were studied in relation to several environmental variables at Dell (northeast) and Newport (north central), AR, during 1972–73 and 1973–74. High fall mortality was attributable to the rainfall and temperature patterns which immediately succeeded larval placement in the field. Effective water drainage was critical for successful overwinter survival. Rainfall, freezing soil temperatures, and duration of exposure (time) accounted for 89.8% of the variation in the overwinter survivorship curves for both locations combined. Time, soil temperatures ≥55°F (12.8°C), incident solar radiation, and rainfall accounted for 96.4% of the variation in the spring emergence patterns at Newport. Overwinter survival ranged from 0.0–5.8% and was higher in the lighter soil types than in clay soils. Percent moth emergence at Newport was ca. 15 times greater than at Dell, which partially explains the differences between the 2 locations in the summer bollworm population densities.

ISSN:0046-225X    

DOI:10.1093/ee/4.6.1015

出版商:Oxford University Press    

年代:1975

数据来源: OUP

摘要:

Rhinocyllus conicusFroeL., a thistle head-feeding weevil introduced from France, successfully controlledCarduus nutansL. (musk thistle) at a Virginia release site (Pulaski Co.) 6 yr after the initial release of 100 adults m 1969. Thistle density was reduced by 95%. This is the 1st documented success of musk thistle control by the introduction ofR. conicus. In 1974 and 1975, ca. 90% of the thistles were attacked by the weevil; over 10% of the terminal heads were aborted. The unaborted heads produced few viable seeds and only the later-blooming, smaller heads escaped severe infestation. Dispersal was only 1.6 km 3 yr after release, but after 6 yr both eggs and adults were detected 32 km from the original release site.

ISSN:0046-225X    

DOI:10.1093/ee/4.6.1025

出版商:Oxford University Press    

年代:1975

数据来源: OUP