摘要:

Preadult mortality and egg production by resulting adults of greenhouse whitefly,Trialeurodes vaporariorum(Westwood), were measured on 13Pelargonium×domesticumcultivars and related to some plant characters. There was a significant effect of cultivars on the mortality of eggs, first to second instars, and total preadult mortality, but not that of third to fourth instars. Total preadult mortality was 2.6 times higher on the least suitable cultivar than the most suitable. Egg mortality was the most influential component shaping total preadult mortality according to the cultivar. Total mortality in each cultivar was significantly and inversely correlated with adult preference, so that the cultivars less preferred by females for oviposition were also less suitable for the survival of progeny. In the mortality–plant character relationship analysis only egg and total mortality were significantly and positively correlated with leaf-soluble glucose content. The cultivar variable also affected egg production by adults that emerged from larvae developed on them, but it could not be correlated with any of the plant characters measured.

ISSN:0046-225X    

DOI:10.1093/ee/23.6.1443

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

We investigated performance for groups of gypsy moth that began feeding during different times in the spring and, thus, coincided with different levels of host foliage maturation. The study was performed by caging groups of newly hatched larvae on host foliage at three different times over a 2-wk period. These times were coincident with the beginning of natural gypsy moth egg hatch in the study area, near peak gypsy moth egg hatch in that area, and near the end of gypsy moth egg hatch for that area. At each establishment date, we placed the new groups of larvae onto the same individual trees that we were using to feed the earlier-established groups. Thus, the only host plant characteristics that varied between the groups established on different dates were those characteristics related to level of host foliage maturation. The tree species we studied were red oak, white oak, bigtooth aspen, and trembling aspen. Major findings include the following: larvae placed earliest had the highest mortality, slowest development times, and lowest larval weights at the end of the season; larvae placed latest had the lowest mortality, fastest development times, highest relative growth rates early on, and maintained the heaviest larval weights throughout the season; and effects of the various host species on gypsy moth growth and survival strongly support host effects seen in our earlier work and the work of others on gypsy moth–host plant interactions. Aspen-fed insects had the highest larval growth rates at the end of the season and were the heaviest pupae, although aspen-fed larvae had high levels of mortality. Red oak-fed larvae had the best growth rates early in the season and the worst growth rates late in the season.

ISSN:0046-225X    

DOI:10.1093/ee/23.6.1450

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Life history of immature maize weevils,Sitophilus zeamaisMotschulsky, was studied at 10–40°C and 43–76% RH. The optimal quantity of corn for minimizing density effects and the optimal observation frequency for minimizing disturbance effects were determined at 30°C and 75% RH. The quantity of corn (32–256 g) provided to five females ovipositing for 24 h did not affect duration of development, but the number of progeny produced increased asymptotically as the quantity of corn provided increased. Frequency of observation (from 1- to 14-d intervals) did not affect duration of development or number of progeny produced. Using moisture contents measured in the life history study, an equation was developed for predicting equilibrium moisture content of corn from temperature and relative humidity. Duration of immature development did not vary with sex, but did vary with test. This suggests that insect strain or chemical composition of the corn must be included as factors in a model predicting effects of environment on duration of immature development. Survival from egg to adult emergence was greatest at 25°C. Sex ratio of emerging adults did not differ from 1:1. The number of multiply-infested kernels was low at all environmental conditions, and survival from egg to adult emergence in these kernels averaged 18%. Maximum daily rate of fecundity, duration of development, and number of progeny produced were optimal at 30°C and 75% RH. An index of environmental suitability indicated that 30°C and 75% RH was the optimal environment for growth of maize weevil populations on corn. Implications of the results for managing maize weevil populations are discussed.

ISSN:0046-225X    

DOI:10.1093/ee/23.6.1459

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Blister beetles responded differently to three alfalfa cultivars and an experimental line in terms of feeding activity and longevity. Blister beetles consumed greater amounts of younger alfalfa than of mature alfalfa. Nutrient concentration tended to decrease as alfalfa growth stage progressed. Field investigations of naturally occurring densities of threestriped and margined,E. funebrisWerner, blister beetles revealed that ‘Kansas Common’ and ‘Arrow’ alfalfas were more attractive than were ‘Riley’ and ‘KS 210’, a glandular-haired experimental line. Several plant parameters, such as alfalfa stem height, stem density, and developmental stage may partially influence the occurrence of threestriped blister beetles,Epicauta occidentalisWerner, on these alfalfa cultivars or experimental lines.

ISSN:0046-225X    

DOI:10.1093/ee/23.6.1472

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Field-caught gravid femaleChironomus crassicaudatusMalloch in central Florida laid egg masses mostly in the morning at onset of photophase in the laboratory. Fifty-seven percent of these females laid a second egg mass in their adult life. Number of eggs averaged 1,338 and 245 per mass in the first and second mass, respectively. Average egg incubation period was 2 d, with initiation and cessation of egg hatch occurring at 1.5 and 5 d after oviposition, respectively. Relationship of body size and fecundity of femaleC. crassicaudatuswas studied by measuring wing length and examining number of eggs per mass and parity. Body size of nulliparous and of parous females had a significant linear relationship with dry body weight. Larger females had a significantly higher number of eggs per mass and percentage parity than small females.

ISSN:0046-225X    

DOI:10.1093/ee/23.6.1480

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Variation in postdiapause emergence patterns of Colorado potato beetle adults over six consecutive years at a single site was only partially explained by cumulative soil heat units. However, soil moisture measured at a depth of 15 cm and daily rainfall accounted for much of the unexplained variation in yearly emergence patterns. We hypothesized that emergence of overwintered beefles was a two-stage process consisting of thermally regulated postdiapause development followed by moisture-driven emergence from the soil. To test this hypothesis we constructed two simulation models that mirrored these processes. One model used soil moisture measured at a depth of 15 cm to drive emergence, while the other used daily rainfall for the same purpose. Both models were able to represent the field data; however, the best congruence was achieved when rain was an independent factor. Because rainfall was a better determinant of moisture, the dynamics of moisture at the soil surface may be of great importance to the beetle. Greater precision in model simulations could probably be achieved by improving the way in which soil moisture dynamics are depicted.

ISSN:0046-225X    

DOI:10.1093/ee/23.6.1485

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

The sperm content of the spermatheca was examined in eleven species of yellowjacket queens collected in the spring of 1987–1989. The sperm count data were highly correlated (r= 0.84) with total cell numbers of mature nests reported for 10 species. Sperm content varied within and among species with mean numbers of sperm ranging from a low of 3,200 ± 600 inVespula consobrinain 1988, to a high of 176,000 ± 46,200 inVespula squamosa, the same year. The implications of mating success and initial sperm quantity variability are discussed.

ISSN:0046-225X    

DOI:10.1093/ee/23.6.1497

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Five important plant hosts of tomato spotted wilt tospovirus at two phenological stages were assayed in the laboratory to determine the host preference of adult western Rower thrips,Frankliniella occidentalis(Pergande).F. occidentalisreadily fed and oviposited on nonflowering romaine lettuce,Lactuca sativassp.longifoliaLam. Cheese weed,Malva palvifloraL. and burdock (gobo),Arctium lappaL. were likewise more preferred for oviposition compared with jimson weed,Datura stramoniumL. or golden crown-beard,Verbesina enceloides(Cav.) Benth&Hook. ex Gray. The following order of feeding or oviposition preference for plants in the vegetative stage was observed:L. sativa>A. lappa=M. palviflora>D. stramonium=V. enceloides. Preference changed at plant flowering withM. palviflora=V. enceloides>D. stramonium=L. sativa. The mean proportion of immatures completing development to adults was greatest at higher temperatures. Leaf suitability forF. occidentalisdevelopment was ranked asL. sativa>M. palviflora=D. stramonium>V. enceloides=A. lappa.Implications of results in tomato spotted wilt tospovirus epidemiology are discussed.

ISSN:0046-225X    

DOI:10.1093/ee/23.6.1501

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

The synthetic female sex pheromone of the oriental beetle,Anomala orientalisWaterhouse, was evaluated in the field and in a sustained-flight tunnel. In a 2-wk period,>150,000 beetles were captured on three golf course fairways in Connecticut. Contrary to earlier reports that these beetles are most active during the warm, sunny portions of the day, we observed that peak activity occurs around sunset. Ten micrograms of either (Z)-7-tetradecen-2-one or an 89/11 (Z/E) blend on a rubber septum was found to be the minimum concentration with which no significant decrease in catch was observed in the field. There was no discrimination between Z and the blend at 1 μg and higher concentrations, but the E-isomer alone trapped significantly fewer beetles than either Z alone or the blend. These results are consistent with the flight tunnel data. The effects of temperature and light intensity on the mating behavior ofA. orientalisalso are discussed.

ISSN:0046-225X    

DOI:10.1093/ee/23.6.1508

出版商:Oxford University Press    

年代:1994

数据来源: OUP

摘要:

Five genotypes of maize were grown under three light regimes in the field. Artificial infestation with European corn borer,Ostrinia nubilalis(Hübner), egg masses resulted in greater leaf feeding damage for plants grown under a UV absorbing plastic (UV−) than for the same genotypes grown under UV transmitting (UV+) plastic or in the open. Leaf bioassays performed on tissue from the three different light regimes showed similar trends. Foliar nitrogen content was reduced as much as 15% for UV− plants. 2,4-dihydroxy-7-methoxy-2H-l,4-benzoxazin-3-one levels were consistently higher in UV− plants as were the levels of cell-wall-bound hydroxycinnamic acids (HCA). Light-activated dimers of HCA called truxillic and truxinic acids were lower in UV− plants. These results indicate that cell-wall-bound truxillic and truxinic acids are an additional resistance mechanism that provide an explanation for increased susceptibility of greenhouse grown plants to folivores.

ISSN:0046-225X    

DOI:10.1093/ee/23.6.1516

出版商:Oxford University Press    

年代:1994

数据来源: OUP