摘要:

Seasonally acclimatized individuals of woolly whiteflyAleurothrixus floccosus(Moskell), cloudywinged whiteflyDialeurodes critifoliiMorgan, andAleurodicus dispersusRussell were exposed to extreme temperatures for 3-h periods and survivorship measured. Survivorship of the 3 whitefly species under field conditions also was followed to determine temperature induçed mortality. Summer survivorship was measured during July, Aug., and Sept. in Fort Lauderdale, FL and winter survivorship was measured during Dec., Jan., and Feb.Heat tolerance was the same among the 3 whitefly species and cold tolerance was different with woolly whitefly>cloudywinged whitefly>A. dispersus. The nymphal overwintering stage is an aleyrodid adaption to cold stress in Florida. My data indicate that the abundance of cloudywinged whitefly populations in northern Florida, and range expansion ofA. dispersusnorthward are both limited by winter cold temperatures.

ISSN:1754-5692    

DOI:10.1093/ee/8.6.1150

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Geranium dissectumL., a previously unreported host ofHeliothisspp., was found infested withHeliothis zea(Boddie) andH. virescens(F.) larvae in Washington Co., MS, in May 1965. Because of cultural practices, this adventive plant from Europe has spread from a limited distribution in 1965 to suitable niches throughout the Delta. Until 1969,H. zeawas the predominant species on this host; since then,H. virescenshas become predominant, and the long term (1965–77) population density ofH. virescenshas become progressively higher. The reversal in species predominance was probably due toH. virescensdeveloping higher levels of resistance thanH. zeato insecticides applied to cotton for control ofHeliothis, but the long term increase in population density ofH. virescensis probably due to increased abundance ofG. dissectum. Calculated averages of 4208H. zeaand 12,735H. virescensadults emerged per hectare ofG. dissectumin Washington Co., MS, in 1978.

ISSN:1754-5692    

DOI:10.1093/ee/8.6.1153

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Onset of evening chorus inTibicen marginalis(Walker) var.dealbata(Davis) was documented for a total of 83 days in 1971, 1977, and 1978, as were associated climatic variables. Expressed in crep units, onset occurs after sunset in early and late summer, but close to sunset during midsummer in Albuquerque, NM. On overcast evenings onset often occurs before sunset.A stepwise multiple regression showed that variables associated significantly with onset were light intensity (log lux), change in barometric pressure in the hour before onset, and season. Seasonal shifts in onset may be due to the interaction of ontogenetic changes in thresholds with simultaneous changes in significant environmental variables.

ISSN:1754-5692    

DOI:10.1093/ee/8.6.1157

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Based on head counts of beef cattle examined in different areas of the state, the number of face flies,Musca autumnalisDe Geer, was observed to be higher east of the Missouri River in South Dakota than in the west. West of the Missouri the fly was uncommon or absent during 1977 and 1978 with the exception of the Black Hills area where there is evidence of an isolated population. Pyramid traps constructed of plywood, painted white, covered with transparent plastic and coated with Tack-Trap® adhesive were placed near herds of beef cattle on each of 5 farms in Brookings Co. Over 99% of the 2049 flies caught from June through November, 1978 were males. On one farm near Brookings, house flies,Musca domesticaL., outnumbered face flies by 8:1 and over 25% of the house flies attracted to the pyramid traps were female.

ISSN:1754-5692    

DOI:10.1093/ee/8.6.1161

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

In laboratory tests (simulated field conditions), larvae of pink bollworm,Pectinophora gossypiella(Saunders), suffered high mortality when soil temperatures were 47°–51°C. However, at these conditions, irrigated-cracked soil provided a protective habitat; cultivated soil reduced larval mobility and caused maximum exposure to the high temperatures. If possible, larvae that fell to the soil moved quickly to avoid high soil temperatures; but then as the temperature decreased, they often moved to alternate pupation sites. On occasion, reproduction of moths from larvae that survived high temperatures was reduced, but results were variable. In field tests of cotton,Gossypium hirsutumL., results were similar. Larval mortality was highest early in the season before plants were large enough to shade the soil. A high percentage of the larvae released on the slopes of the plant beds reached the top of the plant bed and survived. Broad, flat plant bed tops favored survival of pink bollworm larvae more than peaked plant bed tops. Peaking the plant bed to reduce top surface area and increase the angle of the slope and cultivating the bed after the larvae cut out and fell to the soil surface resulted in 70% reduction in emergence of adult moths.

ISSN:1754-5692    

DOI:10.1093/ee/8.6.1165

出版商:Oxford University Press    

年代:1979

数据来源: OUP