摘要:

Combinations of photoperiods and thermoperiods strongly influence the induction of larval diapause in the tufted apple budmoth,Platynota idaeusalis(Walker). Photoperiodic effects may be intensified when the cryophase of the thermoperiod coincides with scotophase of the photoperiod, or the effects may be reduced when the thermophase occurs during scotophase. Photoperiodic and thermoperiodic interactions may be nullified by either a thermoperiod with a high temperature cycle (36:24°C) or a cryophase (15°C) duration of<11 h, even though it coincides with scotophase. Under continuous illumination or darkness, thermoperiods with half cycles of 12 h and 4°C temperature range (23:19°C) to a 16°C temperature range (29:13°C) failed to induce diapause. Larval exposure to one of a series of 26:16°C thermoperiods in which the duration of the cryophase was increased in 2-h increments from 10 to 20 h in continuous darkness showed that thermoperiod under constant darkness does not induce diapause.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1500

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Olfactory behavior of the alfalfa seed chalcid,Bruchophagus roddiGuss., was studied using a Y-tube olfactometer. Leaves, flowers, and pods of glandular and simpled-hairedMedicagoclones with varying seed chalcid resistance were tested. Pods were tested at days 5 to 12 after pollination. Of the plant parts tested, only pods were attractive to the seed chalcids. Attractiveness varied with pod age. Pod aroma stimulated seed chalcid movement to the pods but was not significantly related to resistance or to hair type. Both simple and glandular-haired clones (susceptible and resistant) were attractive for variable periods. Our observations suggest that chemical and mechanical tactile cues are used by the chalcid to select oviposition sites; thus, the use of an olfactometer to screenMedicagolines for seed chalcid resistance is not recommended.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1504

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

One commercial and three experimental maize hybrids were tested for resistance to larvae ofDiabrotica virgifera virgiferaLeConte under uniform controlled infestations. Damage was measured directly by root damage ratings and indirectly by root-pulling resistance and yield reduction; the experimental hybrids were damaged less than the commercial hybrid and were, therefore, considered to be resistant. The same number of adults emerged from both the susceptible and resistant hybrids, but those from the resistant hybrids were heavier. The resistant hybrids may have been nutritionally superior to the susceptible hybrid, or perhaps the resistance was the result of an initial antixenosis followed by physiological compensation. In either case, the resistance was not tolerance, since it appeared to be the result of a response by rootworm larvae to resistant host plants and not the result of a host plant response to larval attack.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1509

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Alfalfa leafcutting bees,Megachile rotundata(F.), and alkali bees,Nomia melanderiCockerell, are inherently more tolerant than honey bees,Apis melliferaL., to most insecticides. However, their greater surface-to-volume ratios cause them to be more susceptible to most field-weathered residues. Insecticides are minimally hazardous to all bees through nectar contamination, and to the alfalfa leafcutting bee via contamination of pollen-nectar stores and leaf pieces. Both acidifiers and acaricides can increase the hazard of insecticide combinations to all three species of bees. Most herbicides and all fungicides are essentially nontoxic to bees. Wild bees often exhibit different poisoning symptoms than honey bees. This is especially notable with exposure to carbaryl.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1513

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

pheromone-baited Pherocon IC sticky traps that were relatively free of captured moths caught about twice as many male gypsy moths as USDA milk carton traps during natural male flight and also in mark-recapture experiments with laboratory-reared males. Traps stapled to the trunks of trees captured more males than traps hung from small branches>2 m from large trees. Behavioral observations revealed three reasons for the higher catch at Pherocon IC traps. First, more males approached within 2 m of the Pherocon IC traps than the milk canon trap in a given time interval and a higher proportion of males engaged in pheromone-induced, zig-zag flight. Second, of those males that came in contact with either trap type, a higher proportion entered the Pherocon trap. Third, there were fewer escapes from Pherocon traps (10%) than from milk canon traps (28%). Milk canon traps captured 9.6% of those males that approached within 2 m and 44% of those that came in contact with the trap, compared with 20 and 76%, respectively, for Pherocon IC traps.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1519

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Larvae of a stem weevil,Cylindrocopturus adspersus(LeConte), overwintered in sunflower stalks in North Dakota, South Dakota, and Minnesota in 1979 and 1980. Population levels averaged 2.0 and 1.6 larvae per stalk in 1979 and 1980, respectively. The highest number of overwintering larvae per stalk occurred in North Dakota. About half of the stalks from each sampled field were infested with larvae. There was no correlation between stalk diameter and number of larvae per stalk. Overwintering sites were in the upper root crown and in the base of the plant stalk, with half the larvae between soil level and 4 cm above soil level. Overwintering sites averaged 5.9 and 4.6 cm above the soil level in 1979 and 1980, respectively.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1526

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Southern corn rootworm larvae and pupae survived best in a controlled soil environment with plant-available water (PAW) ranging from 70 to 100%. Survivability was significantly inferior at the 45 to 55% or 20 to 30% PAW range. Percent clay in southeastern Virginia soils had a less dramatic but significant effect on survivability with the highest clay content soils allowing the best survival. Abrasiveness of soils for peanut production in southeastern Virginia was not believed to be important in immature rootworm survival, but particle size as related to its water holding capacity was important.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1529

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Dispersal of lst- and 2nd-instar larvae ofChoristoneura fumiferana(Clemens) within and between host tree crowns, as well as losses due to landing of larvae on the ground, were observed and quantified with the aid of sticky traps. It was found that 1st-instar larvae disperse mostly within the crown, whereas 2nd-instar larvae disperse more readily between crowns. There was no change in density or vertical distribution of airborne larvae with distance from host trees. Estimated losses due to the landing of 2nd-instar larvae on the ground were very low and depend on stand density and composition. Such losses are partly compensated for by larvae crawling back up the trunk of host trees.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1532

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Oocyte degeneration in virgin moths ofCadra cautella(Walker) andPlodia interpunctella(Hübner) occurs in temperatures ranging from 20 to 33°C. Combined with relative humidity, temperature is the dominant factor. Unlike other species of insects where oosorption occurs at low temperatures that induce diapause, oocyte degeneration in the moths is confined to higher temperatures. Although ooeytes may be sources of food and moisture, oocyte degeneration inC. cautellaandP. interpunctelladoes not increase the longevity of the moths. Above threshold temperatures, the remains (relics) of oocyte degeneration can be used to estimate the age of virgin moths.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1539

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Healthy adults ofAmyelois transitella(Walker) lived about 1.5 times longer and laid about 5- to 10-fold more eggs than did stunted, diseased moths. Healthy females paired with healthy males laid significantly more (P0.05) in the percent hatch of eggs laid by healthy and diseased females. There was no evidence of transovum transmission of viruses by diseased moths.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1542

出版商:Oxford University Press    

年代:1983

数据来源: OUP