摘要:

The squash bug,Anasa tristisDeGeer, undergoes a reproductive diapause from late summer to spring in northeastern Kansas. In the laboratory, diapause was induced in 100% of adult females reared under photoperiods shorter than 14:10 (L:D) and in a variably lower percentage of the population under all longer photoperiods. The critical photoperiod for diapause induction falls between 14:10 and 14.5:9.5; this range compares closely with prevailing natural daylengths when 50% of the adult population enters diapause in the field. Between October and March, short daylengths maintained, and long daylengths terminated, diapause in field-sampled adults. Under natural daylength at 26°C, the duration of diapause became progressively shorter with advancing sample date. In nature, the photoperiodic maintenance of diapause is completed in most of the population by late May. A prolonged diapause probably serves to prevent premature postdiapause development during the thermally variable spring conditions encountered in Kansas. Some implications of these findings for biological control and pest management programs are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/17.3.427

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Disruption of orientation ofEuxoa ochrogaster(Guenée) males to synthetic bait was studied in a flight tunnel and in small field plots, using synthetic pheromone components as disruptants. Field tests showed that increasing the dose from 0 to 100 μg per dispenser of the blend of all four components (Z5-12:Ac + Z7-12:Ac + Z5-10:Ac + Z9-12:Ac) or that of Z5-12:Ac and Z7-12:Ac, individually, resulted in a sharp increase in disruption up to a maximum of 75%; a further increase in the dose to 1,000 μg per dispenser resulted in only a small and gradual increase in disruption, reaching a maximum of 88%. Z5-10:Ac caused approximately 78% disruption at levels of 100 μg and 1,000 μg per dispenser, and Z9-12:Ac was least effective at these doses. Flight tunnel and field observations showed that with blends, the mechanisms of disruption varied in relation to the concentrations used. The primary cause of disruption was competitive attraction at low dose levels and reduction in searching effort at high dose levels. With single components, irrespective of concentrations used, the cause of disruption was primarily reduction in searching effort. Based on these studies and those onEuxoa messoria(Harris) andMalacosoma disstria(Hübner), it is suggested that in moths, depending upon the species, functional nature of the pheromone components, concentrations used, and the method of disruptant dispenser placements, individual or blends of components can cause orientation disruption by competitive attraction and by modulating the behavior of males, particularly by reducing the searching effort.

ISSN:1754-5692    

DOI:10.1093/ee/17.3.432

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Electroantennogram responses to isomers of dodecenyl, tetradecenyl, and hexadecenyl acetates and alcohols followed by field screening tests indicated that (E)-9-tetradecenyl acetate (E9-14:Ac) is attractive to maleZeiraphera CanadensisMutuura and Freeman. Traps baited with dosages of either 1 or 10 μg of E9-14:Ac on rubber septa were the most attractive. Traps hung in white spruce trees caught significantly more males than those hung on poles between trees. Vertical location of traps within the tree crown was important; mean catches were greatest in the upper third of the crown. No consistent differences in the numbers of males caught were obtained in a comparison of two nonsaturating traps (Multi-Pher and Uni-trap), and one sticky trap (Pherocon ICP).

ISSN:1754-5692    

DOI:10.1093/ee/17.3.442

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

The effects of temperature, relative humidity, and concentration and amount of trypticase soy broth (TSB) on regurgitation byMusca autumnalisDeGeer were determined. The highest amounts and concentrations of TSB resulted in the most frequent regurgitation. Regurgitation occurred most often at the lowest relative humidities (RH) examined, and regurgitation was most pronounced at 29°C. Significant interactions between RH and concentration of TSB, RH and amount of TSB, concentration and amount of TSB, temperature and concentration of TSB, and temperature and amount of TSB were found.

ISSN:1754-5692    

DOI:10.1093/ee/17.3.448

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

The pink bollworm,Pectinophora gossypiella(Saunders), was reared on the bolls of cotton plants grown in CO2-enriched (649 μl/liter) and ambient CO2, (371 μl/liter) chambers and in two open field plots, one with free-air CO2enrichment (522 μl/liter) and one without enrichment (ambient CO2, 360 μl/liter). The effects of increased CO2levels on growth and development were examined. There was no difference in pupal weights of pink bollworm raised on CO2-enriched cotton compared with those raised on ambient CO2cotton (26.80 versus 26.64 mg, respectively). Also, there was no difference in developmental time (21-27 d). Analysis of percent seed damage by larvae showed no differences between CO2- enriched and ambient CO2cotton. These results were attributed to the nutritional qualities of the seed remaining the same (specifically the carbon/nitrogen ratio) despite CO2and photosynthetic changes in the plant.

ISSN:1754-5692    

DOI:10.1093/ee/17.3.452

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Responses of seven species of pine-infesting beetles to traps baited with either turpentine, ethanol, turpentine and ethanol released from separate dispensers, or a 1:1 solution of turpentine and ethanol released from one dispenser were assessed in three field experiments. The weevil species,Pachylobius picivorus(Germar), and the cerambycid pine sawyer,Monochamus carolinensis(Olivier), were attracted to turpentine and were unaffected by the addition of ethanol. The ambrosia beetle,Xyleborus affinisEichhoff, responded to ethanol alone but was not attracted to turpentine, nor did the presence of turpentine significantly affect its response to ethanol. The remaining four species displayed responses to turpentine that were enhanced by the addition of ethanol, but in different ways according to the method of deployment.Hylobius pales(Herbst) weevils andM. titillator(F.) sawyers displayed greatest attraction to turpentine and ethanol whether they were released from side-by-side dispensers or as a solution from one dispenser. The black turpentine beetle,Dendroctonus terebrans(Olivier), displayed the highest response to turpentine and ethanol in solution. The ambrosia beetle,X. pubescensZimmermann, responded in low numbers to turpentine or ethanol deployed singly, but displayed an enhanced response (20-fold increase) to turpentine and ethanol deployed side-by-side and an even greater response (60-fold increase) to a solution of turpentine and ethanol. Reasons for increased responses by some species to a solution of turpentine and ethanol over the two released separately are not clear; they may lie in different dosages or evaporation rates of volatiles in the field. Laboratory analyses of trapped headspace volatiles from dispensers containing only turpentine and those containing a solution of turpentine and ethanol revealed no differences in the amounts of four principal monoterpene hydrocarbons (α-pinene, camphene, β-pinene, and limonene) released over time. The synergistic effect of turpentine and ethanol for some species and not others may point to ecological differences between species with regard to the condition of preferred host material.

ISSN:1754-5692    

DOI:10.1093/ee/17.3.456

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

The water relations and desiccation tolerance of migrating adult garden millipedes,Oxidus gracilisKoch, were examined. Both sexes contained about 60% total body water (TBW), and the percentage TBW lost increased linearly with desiccation time. Knock-down caused by desiccation occurred at 6.6 h for females and 5.2 h for males. The cuticular permeability was not significantly different between sexes and ranged between 77 and 79 μg cm−2h−1mmHg−1. Desiccation significantly affected millipede movement. Desiccation for 1 h at 30°C and 0–2% RH caused a 54 and 28.9% decrease in movement for female and maleO. gracilis, respectively. A biologically based cultural control strategy is presented.

ISSN:1754-5692    

DOI:10.1093/ee/17.3.463

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

E-64, a specific inhibitor of cysteine proteinases, was incorporated into artificial seeds at low levels (0.01–0.25% by weight). It prolonged developmental time and increased mortality of the larval cowpea weevil,Callosobruchus maculatus(F.), in direct proportion to its concentration in the artificial seeds. The fecundity of females emerging from the artificial seeds was significantly decreased by E-64 concentrations of 0.06% and higher. These observations are compatible with the hypothesis that the midgut cysteine proteinase inC. maculatusis essential for normal growth and development.

ISSN:1754-5692    

DOI:10.1093/ee/17.3.467

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

The effect of selected temperatures, relative humidities, and levels of free water at time of eclosion, and the effect of selected temperatures and relative humidity during development, were measured on the number of adultTrichogramma pretiosumRiley emerging from parasitized eggs ofHeliothis zea(Boddie), and on the frequency of abnormal (brachypterous) wings among emerged adults. At time of eclosion, highest mean rates of emergence occurred at 32 ± 1°C and 60 and 80% RH. Significant declines in adult emergence occurred above 80% and below 40% RH at all temperatures evaluated. Temperatures of 38 and 43 ± 1°C lowered mean rates of adult eclosion by>70% under optimum relative humidity.T. pretiosumadults that emerged at 27 and 32 ± 1°C and 40, 60, and 80% RH generally had fully developed wings, whereas adults that emerged at higher and lower relative humidity and adults that emerged at 35, 38, and 43 ± 1°C (all RH) had significantly higher mean frequencies of brachypterous wings than did the control. Brachypterous wings among adultT. pretiosumemerging at 38 and 43 ± 1°C generally exceeded 50%. Eclosion responses ofT. pretiosumreared at day temperatures of 27, 32, and 35 ± 1°C (21 ± 1°C night) and a range of relative humidity from 10 to 100% generally paralleled those ofT. pretiosumexposed to similar ambient conditions only at time of eclosion. Largest mean numbers ofT. pretiosumper host emerged from host eggs held for development and eclosion at 27 and 32 ± 1°C and 80% RH. Only when reared at day temperatures of 32 and 35 ± 1°C and 40, 60, and 80% RH was the mean number ofT. pretiosumemerged with brachypterous wings the same as that of the control. Eclosion ofT. pretiosumfrom eggs ofH. zeaheld on filter paper substrates was statistically lowered when levels of free water reached or exceeded saturation. If augmented Trichogramma are ever to perform as expected, requisites for their successful eclosion and ambient conditions in which they are expected to emerge and perform must be identified and carefully aligned.

ISSN:1754-5692    

DOI:10.1093/ee/17.3.470

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

The role of plant allelochemicals in reducing the ability ofBacillus thuringiensisvar.kurstakiBerliner to kill larvae ofManduca sexta(L.) was studied by comparing the effects of the alkaloid nicotine and the flavonoid rutin on the toxicity ofB. thuringiensis.Concentrations of nicotine and rutin reflecting levels found in tobacco and tomato plants (0, 0.2, 0.4, 0.6, 0.8, 1.0% wet weight) were incorporated into synthetic diet containing 0.001%B. thuringiensisandB. thuringiensis-free diet. Survivorship ofM. sextalarvae increased at higher levels of nicotine (0.6, 0.8, 1.0% wet weight), but higher concentrations of rutin did not increase larval survivorship. Experiments on colony growth ofB. thuringiensison nutrient agar containing nicotine or rutin (0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9% wet weight) demonstrated that nicotine reduced colony growth to a greater extent than rutin. Consequently, plant allelochemicals potentially are an important factor in reducing larval mortality caused byB. thuringiensison certain crops. Specialist herbivores that can tolerate high concentrations of allelochemicals may gain protection from pathogens by feeding on plants or plant parts with higher levels of toxins.

ISSN:1754-5692    

DOI:10.1093/ee/17.3.476

出版商:Oxford University Press    

年代:1988

数据来源: OUP