摘要:

Temperature-dependent development of laboratory- and field-wintered eggs ofCampylomma verbasci(Meyer) was described using data from constant-temperature laboratory experiments. Time required for hatch of overwintering eggs declined throughout winter until the end of February, after which increasing exposure to cold conditions had no effect on median hatching time. Developmental rates of nondiapausing overwintered eggs were compared at 5.0, 8.8, 9.4, 12.9, 15.0, 18.0, 20.9, 23.0, and 25.8°C. Variation in developmental rates across temperatures was modeled (R2= 0.99) with a cumulative Weibull distribution. A nonlinear, six-parameter developmental model with low- and high-temperature inhibition accurately described (R2= 0.99) median developmental rates of all temperatures. Least-squares linear regression (rate = −0.05017 + 0.00545 [temp]) described development in the linear region (12.9–20.9) of the development curve. The lower developmental threshold (9.2 ± 0.1°C) was determined by extrapolation of the linear regression through thex-axis. This relationship predicted that median (50%) development required 183 ± 1.2 degree days above the base temperature. The linear degree-day model and a stochastic simulation model incorporating the Weibull distribution and nonlinear development model were validated using field phenology data from several sites and years. Using daily air-temperature minima and maxima and a starting date of 1 January, the degree-day model was 5.2 ± 4.3d late and the simulation model −0.5 ± 3.4d early in predicting median hatch of overwintered eggs. Both models were more accurate than a (6.6 ± 5.0d late) previously developed empirical index. This article discusses the use of phenology models in the management ofC. verbasci.

DOI:10.1093/ee/23.5.1224

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

The aphidAphis gossypiiGlover generally is seen as a highly polyphagous species with mainly parthenogenetic reproduction. This study shows that genotypes living on cucumber and chrysanthemum behave as genetically distinct host races, Little or no reproduction occurs after reciprocal host transfers. Rearing for three generations of the cucumber clones on chrysanthemum did not lead to a better performance measured as developmental time and adult weight at the day of first reproduction. Only larval mortality decreased over these three generations. Thus, performance is not likely to improve through induction. Further, the chrysanthemum clones ofA. gossypiiwere observed to produce sexual females and males under short day conditions. These results show thatA. gossypiideveloped distinct host races with different abilities of colonizing host plants and with more potentials of sexual reproduction, and consequently evolutionary differentiation, than previously regarded.

DOI:10.1093/ee/23.5.1235

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Insect populations in 14 bins of newly harvested wheat on eight farms in Kansas were monitored with sticky traps in the bin headspace and with grain samples. Sticky trap catches during the first 3 wk of storage were used to provide an estimate of the species and densities of insects that were present in the headspace. Grain samples were taken every 2 wk during the first 3 mo of storage to provide an estimate of population growth under the grain temperature and moisture conditions in the bins. The sticky traps correctly predicted whether lesser grain borer,Rhyzopertha dominica(F.), and rusty grain beetle,Cryptolestes ferrugineus(Stephens), would be found in the grain samples in 85.8 and 78.6% of the bins, respectively. Traps were less reliable for foreign grain beetle,Ahasverus advena(Waltl), and hairy fungus beetle,Typhaea stercorea(L.), with correct predictions in 57.1 and 42.9% of bins, respectively. Indianmeal moth,Plodia interpunctella(Hubner), was found in both traps and grain samples in only one bin and red flour beetle,Tribolium castaneum(Herbst), and sawtoothed grain beetle,Oryzaephilus surinamensis(L.), were not found in both traps and grain samples in any of the bins. The traps in the center of the bin caught 4.7–14.2 times more beetles than those on the bin walls, but only 1.3 times moreP. interpunctellaadults. The total numbers ofC. ferrugineusadults in the grain samples could be predicted better from the product of mean grain temperature times maximum grain moisture than from sticky trap catch.

DOI:10.1093/ee/23.5.1241

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Sodium hypochlorite (NaOCI) tolerance characteristics ofMesocyclops aspericornis(Daday),Mesocyclops longisetus(Thiebaud),Aedes aegypti(L.),Culex quinquefasciatusSay, andAnopheles farautiLaveran (sibling species no. 1) were investigated by measuring their mortality in response to total residual chlorine concentrations ranging from 0.0 to 2.0 ppm. Of the twoMesocyclopsspecies evaluated,M. aspericornisshowed the greatest sensitivity to chlorinated water, with an LD50value of 0.47 ppm total residual chlorine.M. longisetusexhibited the greatest suitability for treatment of chlorinated stored water, with an LD50value of 1.01 ppm total residual chlorine.Cx. quinquefasciatus,Ae. aegypti, andAn. farautihad LD50values of 0.71, 1.07, and 1.35 ppm total residual chlorine, respectively. The laboratory findings were compared with a field study of chlorine levels in water tanks targeted for treatment withMesocyclopsin Fortaleza (3° 45′ S, 38° 35′ W), Brazil.

DOI:10.1093/ee/23.5.1245

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

In western Newfoundland the pitcherplant mosquito,Wyeomyia smithii(Coquillett), is absent from many potential habitat patches (bogs with populations of the purple pitcher plant,Sarracenia purpurea). Bog size, pitcher-plant density, and wind exposure in bogs were estimated and ranked. Rank ordered variables were intercorrelated and any single variable had significant predictive power for mosquito occurrence, but only wind exposure was significant in a multiple regression. Bogs exposed to wind harbored smaller or no mosquito populations. A likely explanation for this pattern is that reduced winter snow cover induces high overwinter mortality of diapausing mosquito larvae.

DOI:10.1093/ee/23.5.1250

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Spined soldier bugs,Podisus maculiventris(Say), were fed different regimens of prey and then dissected at different ages to measure lipid content and reproductive status to determine how the predator allocates food reserves between metabolic and reproductive needs under low prey inputs. We found that as the interfeeding interval increased, the amount of lipids increased and the number of eggs oviposited decreased. When starved individuals were switched from a low- to a high-prey input regimen, the number of eggs laid increased after 4d. These findings suggest that to maintain longevity, lipids were stored, while at the same time, reproduction declined. Such trade-offs probably allowP. maculiventristo persist in various environments, including those characterized by scarce or unpredictable food inputs.

DOI:10.1093/ee/23.5.1254

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Many grasshopper species feed on dead insects, including other grasshoppers. We observed the responses of grasshoppers to newly available grasshopper cadavers at sites in southwestern Montana. Cadavers were first fed upon by grasshoppers within a mean of 5 min of their placement at one site and within 13.7 min at another. Species differed in the propensity to be the first to arrive at and feed on newly available cadavers.Melanoplus packardiiScudder were relatively more common in samples of the first grasshopppers to arrive at and feed upon cadavers than they were in sweep samples of the local grasshopper communities.Ageneotettix deorum(Scudder), in contrast, were relatively less abundant in samples of feeders than in the community and frequently did not respond to nearby cadavers. The time that elapsed before a cadaver was fed upon by grasshoppers was negatively correlated with soil surface temperature across a range of 16 to 64°C. The rate at which the cadavers were consumed was positively correlated with temperature. At lower temperatures, the rate of cadaver discovery was probably constrained by lower rates of locomotion. At temperatures>50°C, feeding was constrained by thermal stresses that were partially overcome by postural adjustments and microhabitat selection. We discuss the mechanisms by which differences among species could arise and the relationship of the results to our previous study of aggression among grasshoppers at cadavers.

DOI:10.1093/ee/23.5.1260

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

A series of biological assays was performed in the laboratory to examine the oviposition response ofAedes aegypti(L.) to sites containing, or which had previously contained, conspecific larvae parasitized by the digenean,Plagiorchis elegans(Rudolphi). Waters containing parasitized larvae received significantly fewer eggs than waters containing unparasitized larvae. Larval holding waters that had previously contained unparasitized larvae received significantly more eggs than either waters that had previously contained no larvae or parasitized larvae. Waters that had contained no larvae received significantly more eggs than larval holding waters that had contained parasitized larvae. When these waters were boiled, treated with antibiotics to curb bacterial growth, or filtered sterilized, larval holding waters that had contained parasitized larvae continued to receive significantly fewer eggs than larval holding waters that had contained unparasitized larvae. We propose that gravidA. aegyptiare deterred from ovipositing in response to a chemical found in waters containing parasitized larvae. The ecological implications of this selective oviposition are discussed.

DOI:10.1093/ee/23.5.1269

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

The compatibility of abamectin withEncarsia formosaGahan (Hymenoptera: Aphelinidae) as a part of integrated pest management of the greenhouse whitefly,Trialeurodes vaporariorumWestwood (Homoptera: Aleyrodidae), was assessed in a series of laboratory and greenhouse experiments. In laboratory experiments using commercially formulated abamectin at the concentration recommended for greenhouse use, mortality of the adult parasitoids ranged from 100%, when exposed to 2-h-old abamectin residues on bean plants(Phaseolus vulgaris)in the presence of whitefly larvae, to 0% when exposed to 24-h-old residues without whitefly larvae. More than 50% of theE. formosasuccessfully eclosed from parasitized whitefly pupae on bean leaves dipped in formulated abamectin. In the greenhouse experiment, the combined treatment of abamectin andE. formosamaintained significantly lower densities of whiteflies on poinsettia,Euphorbia pulcherrima(Willdenow), throughout the season with fewer abamectin applications than did abamectin alone. Moreover, the percentage of parasitism did not differ significantly among plants treated with and without abamectin. Abamectin might be used to reduce whitefly numbers on poinsettia without eliminating the parasitoid population when releases ofE. formosaare not satisfactory. A possible explanation for the partial selectivity of abamectin toE. formosais discussed.

DOI:10.1093/ee/23.5.1277

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Pickleworm,Diaphania nitidalis(Stoll), and melonworm,Diaphania hyalinata(L.), larvae were susceptible to parasitism byCardiochiles diaphaniaeMarsh. Melonworm larvae were more susceptible to parasitism than pickleworm, but both exhibited reduced weight gain and head capsule growth in later stadia compared with nonparasitized conspecifics and then perished following initiation of wandering before pupal molt. Melonworm larvae parasitized when in advanced stadia achieved a greater final weight than larvae parasitized when young. Parasitoid larval development time was longest following parasitization of young melonworm, but not significantly different in melonworm larvae parasitized in middle or later instars. Compared with nonparasitized melonworm larvae, the prepupal wandering stage was abbreviated in melonworm larvae parasitized when young, and extended in melonworm larvae parasitized in later instars. Overall, parasitoid development time was significantly longer in pickleworm hosts than melonworm. Adult parasitoid weight increased with host age at the time of parasitization when melonworm served as host and was highest in middle-instar larvae when pickle worm served as host.C. diaphaniaedeveloping in pickleworm larvae weighed significantly more than those developing in melonworm larvae.

DOI:10.1093/ee/23.5.1283

出版商:Oxford University Press    

年代:1994

数据来源: OUP