摘要:

ThreeApium graveolens(L.) varieties and cultivars within varieties were evaluated for host plant suitability to two polyphagous lepidopteran herbivores: the beet armyworm,Spodoptera exigua(Hübner), and the cabbage looper,Trichoplusia ni(Hübner). Overall, there were no significant differences in survivorship, developmental time, and pupal weight ofS. exiguaorT. nireared on the two varietiesA. graveolensvar.dulceandA. graveolensvar.rapaceum. Intravarietal differences did exist between cultivars ofA. graveolensvar.rapaceum; S.exiguareared on ‘Kockanski’ had a significantly lower mean survivorship to pupation (27.5 versus 82.5%), a significantly longer mean time to pupation (18.5 versus 13.7 d), and a significantly lower mean pupal weight (37.6 versus 75.0 mg) thanS. exiguareared on ‘PI 223333’, a different cultivar ofA. graveolensvar.rapaceum. In contrast to the response ofS. exigua, there were no significant differences in the life history variables amongT. nireared on the same cultivars ofA. graveolensvar.rapaceum.Quantitative nutritional analysis showed that the differential response ofS. exiguaandT. nito the twoA. graveolensvar.rapaceumcultivars was caused by inability ofS. exiguato compensate for reduced efficiencies of conversion of ‘Kockanski’ to larval biomass. Variation in total nitrogen contents were not responsible for the observed variation in compensatory abilities.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1636

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

In this study, respiration rates of individual gypsy moth eggs were monitored using an infrared gas analyzer as a means of determining transition between ontogenetic states under different temperature conditions. Temperature had a significant effect on respiration rate regardless of the age or ontogenetic condition of the egg. Duration of the prediapause state was temperature-dependent, and the rate of development versus temperature relationship was described by a nonlinear function. Variability of the population in duration of the prediapause state was described by a cumulative Weibull function. Data from previous studies that suggested a diapause process with changing thermal responsiveness are reinterpreted within the context of a three-phase, sequential, phenological process.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1645

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

It was hypothesized that the northward spread of the eucalyptus longhorned borer,Phoracantha semipunctataF., in California is limited by winter temperature conditions. The cold tolerance of prepupal stages was tested by exposing infested logs to cold temperature treatments of −5,0, +5, and +10°C for periods of 1, 3, 7, and 30 d. Temperature treatments had no affect on survivorship to adulthood or longevity but did reduce adult weight relative to nontreated control logs. Increasing exposure time to all cold temperatures significantly reduced both survivorship and adult weight but had no affect on adult longevity. Long periods of exposure to cold temperatures delayed emergence of adults and resulted in more closely synchronized emergence. Cold temperatures are unlikely to prevent the spread of this pest into most zones occupied by its eucalyptus host plants. In addition, increasing densities of prepupae in logs also resulted in significantly reduced survivorship to adulthood but did not affect adult weight or longevity.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1653

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Constant-temperature development studies were conducted with overwintering postdiapause eggs and first-generation nymphal stages of white apple leafhopper,Typhlocyba pomariaMcAtee. Plots of development rates versus temperature were nonlinear over the range of temperatures tested, 13–30°C. Optimum nymphal development for each stage occurred over a narrow range of temperatures, 26–28°C. Developmental rates (times) for each life stage were normalized and fit to cumulative curves of development (Weibull and logistic functions) to produce a predictive phenology model. Comparison of these curves with the development of two nymphal cohorts under field temperatures showed that the model was significant. However, the fit of the model to data on cumulative egg hatch from three orchards was poor. Comparison of the model with cumulative counts of first generation nymphal stages sampled weekly or biweekly in several orchards between 1986 and 1989 showed the model was on average 0–4 d late in predicting 1, 50, and 99% completion of each nymphal stage. Yet, the model predicted the occurrence of these three events within 7 d of the observed event in>90% of the comparisons. Prediction of the timing of peak population density of instars 1–3 (the most susceptible life stages to organophosphate insecticides) was<3 d when stage-specific survivorship rates of<70% were included in the model.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1659

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The numbers and distributions of pine engraver,Ips pini(Say), predators, and secondary subcortical associates responding to racemic ipsdienol in Wisconsin were analyzed over 4 yr with regard to date, height in the canopy, and distance from the margin of previously killed trees. The largest difference in response patterns between predators andI. piniwas in seasonal occurrence. MostI. piniwere caught late in the season, whereas most predators were caught much earlier. Additional differences were observed in spatial distributions and time by space interactions. These results suggest that subtle behavioral or developmental (or both) shifts may allow some bark beetles to temporarily escape from predators that exploit scolytid pheromones as kairomones. Factors contributing to discrepancies between predator and prey trap catch can also be exploited in pest management. Semiochemically based control treatments can be scheduled to greatly reduce the proportion of beneficial insects caught without substantially reducing efficacy. Additionally, this information can be used to improve population estimates of predators and guide natural enemy introduction strategies.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1665

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Specific hunger and effects of specific hunger on attractiveness of three types of olfactory feeding attractants to a laboratory strain of Mexican fruit fly,Anastrepha ludens(Loew), were investigated in laboratory bioassays and greenhouse flight chamber experiments. Newly emerged flies (up to 4 d old) fed preferentially on sugar over protein, whereas 5–9–d–old flies undergoing sexual maturation fed about equally on sugar and protein. Sugar or protein deprivation increased feeding preference for sugar or protein, respectively, whereas constant access to sugar or protein decreased preference for the respective nutrient. Sugarv hunger, whether age-dependent or deprivation-induced, increased attractiveness to flies of CEH, a fruit-derived attractant consisting of 1,8-cineole, ethyl hexanoate and hexanol, relative to two proteinaceous lures. Protein hunger dramatically increased attractiveness of bacteria, a purported protein source for fruit flies, relative to CEH. Protein hunger also increased attractiveness of torula yeast, a commonly used proteinaceous lure, compared with CEH, although attractiveness of torula yeast did not become greater than attractiveness of CEH. Combinations of torula yeast and CEH were not more attractive than CEH alone to any age-feeding history groups of flies. Combinations of CEH and bacterial odor were never more attractive than bacterial odor alone to protein-hungry flies and were actually less attractive then CEH alone to the one group of sugar-hungry flies (2–3–d–old unfed) that was tested.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1680

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Detoxifying enzymes and susceptibility to three insecticides ofApanteles plutellaeKurdj andDiadegma semiclausumHellen, parasitoids of diamondback moth larvae, were determined. Both insects were susceptible to malathion and methyl parathion and were considerably tolerant to fenvalerate. Although the attempt to correlate this susceptibility with the detoxication capabilities, in terms of activities toward model substrates of carboxylesterase, glutathione S-transferase, and microsomal monooxygenase, of these two parositoids was unsuccessful, the possibility of using this means to assess the potential for development of insecticide resistance in natural enemies is discussed.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1687

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

A series of life tables based on field observations of mortality of citrus blackfly,Aleurocanthus woglumiAshby, in a commercial orchard in León, Nicaragua (1986–1989), indicate that the solitary endoparasitoidEncarsia opulenta(Silvestri) is an important factor in the observed declines of outbreak citrus blackfly populations in 1986 and 1987. Parasitization byE. opulentawas disrupted by intensive rainfall and subsequent pesticide applications in the orchard but was restored when insecticide use was eliminated or dry weather conditions resumed. By mid-1988, survival of immatures to the adult stage was below theoretical replacement levels necessary for population increase, and populations declined to low, subeconomic densities. In late October 1988, heavy wind and rain of Hurricane Joan disrupted parasitoid activity and created conditions for potential outbreak adult citrus blackfly survivorship.E. opulentareexerted control of the population to low-density subreplacement levels within the following four host generations.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1691

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Data on the natural control of cereal aphids,Diuraphis noxia(Mordvilko),Metopolophium dirhodum(Walker), andSitobion avenae(F.), by entomophthoralean fungi and hymenopterous parasitoids on furrow-irrigated spring wheat in southwestern Idaho are presented. The important fungi involved werePandora neoaphidis(Remaudire&Hennebert) Humber andConidiobolusspp., including C.obscurus(Hall and Dunn) Remaudire,C. thromboidesDrechsler, andC. coronatus(Constantin) Batko. During 1986–1989,M. dirhodumandS. avenaepopulations usually reached or exceeded economic levels.D. noxiadid not enter the region until late June 1987. It was the first aphid found infesting the crop in 1988 and reached high densities that summer but was not found in 1989, perhaps because of mortality during an extremely cold winter. Fungal infection occurred ≍2,3, and 6 wk after colonization of the crop byM. dirhodum, S. avenae, andD. noxia,respectively. Epizootics occurred each summer but usually after the crop was damaged by large aphid populations. An exception occurred during 1987 whenM. dirhodumandS. avenaepopulations were effectively suppressed by mycoses, apparently enhanced by unusually frequent rainfall during late May and June.M. dirhodumexperienced much higher mortality from fungal infection than didS. avenaeandD. noxia. P. neoaphidiswas the dominant fungus infectingM. dirhodumandD. noxia,whereasConidiobolusspp. were most important onS. avenae. Entomophthora chromaphidisBurger&Swain and twoZoophthoraspecies sporadically infected cereal aphids. Parasitoids, mainlyAphidius erviHaliday forS. avenaeandM. dirhodumandDiaeretiella rapae(M'Intosh) forD. noxia,usually attacked cereal aphids earlier than the fungi but were less influential during the decline of host populations. Multiple regression and correlation analysis indicated that mycoses and parasitoids made significant contributions to the reduction of peak populations of each aphid species compared with the influence of crop maturation. Weak correlation between fungal infection and host density and climatic factors (r2ranging from 0.35 to 0.53) was found. Development of fungal infection seemed to be better correlated with host density than with climatic factors. Precipitation was more associated with fungal infection ofS. avenae,which inhabits upper portions of the host crop, but had little effect on that ofM. dirhodumandD. noxia,which inhabit more humid microenvironments. No other climatic factors were significantly correlated with fungal infection. A hypothesis is proposed that the site on a wheat plant typically occupied by an aphid species influences the development of mycoses.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1699

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Tetrastichus gallerucae(Fonscolmbe), an egg parasitoid of the elm leaf beetle,Xanthogaleruca luteola(Müller), apparently has failed to become established at most sites in 15 northern California counties where it was introduced from 1974 to 1989. EstablishedT. gallerucaepopulations are low or undetectable until late in the season. Poor establishment is due to poor survival during the host-free period, and the life stage and habitat ofT. gallerucaeoverwintering is unknown. Degree-day modeling indicates that adults, and at some locations immatures, can survive the host-free period in a state of quiescence. However, laboratory and field studies reveal that few parasitoids possess the longevity to overwinter successfully. TheT. gallerucaestrains introduced to date in northern California appear to lack the temperature adaptations necessary to survive the host-free period in sufficient numbers to provide early-season biological control of elm leaf beetle.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1711

出版商:Oxford University Press    

年代:1991

数据来源: OUP