摘要:

A description of the courtship and mating behavior ofBemisia tabaci(Gennadius) is presented. Upon emergence, both sexes were clear winged and sexually immature. They matured during the next 24 h and their wings were coated with wax. Newly emerged males were attracted to 1-d-old females and sometimes initiated courtship that rarely persisted. Males between 10 and 24 h old readily initiated courtship but failed to complete antennation. Newly emerged adult females were not attractive to males for about 10 h. Females accepted courting males 20–24 h after emergence. The precopulatory, copulatory, and postcopulatory behaviors, including the time spent at each step, are described for mature adults. Unsuccessful sexual encounters included male and female rejection, male–male interference, and misdirected sexual behavior. A comparison of the sexual behavior ofB. tabaciandTrialeurodes vaporariorum(Westwood) suggests thatB. tabaci, likeT. vaporariorum, may use a sex pheromone.

ISSN:1754-5692    

DOI:10.1093/ee/18.5.800

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Adults ofHeliothis virescens(F.) were provided untreated (0 ppm) or rubidium-treated artificial nectar (2,000 ppm rubidium chloride in 10% honey-water) for a 24-h period upon eclosion or 48 h after eclosion. All rubidium-treated females and>90% of the eggs from both rubidium treatment conditions contained reliably detectable levels of the maternal label. Significant differences were found in element content of eggs produced over the 10-d period, and some significant differences were found in the element content of eggs produced by different females within treatment groups per oviposition day. However, detectability of rubidium was not negatively affected.

ISSN:1754-5692    

DOI:10.1093/ee/18.5.807

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

The persistence of a nuclear polyhedrosis virus (NPV) on soybean after death and lysis of NPV-killed (AgNPV)Anticarsia gemmatalis(Hübner) larvae on the plants was examined. Bioassays of virus on leaflets (which had no direct contact with the diseased larvae) collected from these plants showed that AgNPV activity persisted on the plants for the entire 7-wk test period, with up to 62.7% larval mortality in bioassays conducted after the seventh week. Regardless of the canopy location (higher or lower) of the virus-killed cadavers, AgNPV activity was higher on the leaflets collected from the lower canopy after 2 wk and remained so for the duration of the test. This may be related to movement of AgNPV into the lower canopy by rainfall and wind where it can be better shielded from sunlight inactivation by the foliage. A separate test was conducted in which uninfected larvae were caged for 5 d on soybeans at weekly intervals after death of AgNPV-infected larvae. The mean larval mortality during the 4-wk period of this test was higher in treatments in which AgNPV-killed cadavers had died in the upper canopy. This may be explained by the preference of the uninfected larvae for the upper canopy.

ISSN:1754-5692    

DOI:10.1093/ee/18.5.811

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Disease in spruce budworm,Choristoneura fumiferana(Clemens), caused by the microsporidianNosema fumiferanae(Thomson), increased larval susceptibility to mortality byBacillus thuringiensis(Berliner) treatments compared with larvae free ofN. fumiferanaedisease. The median lethal concentration (LC50) ofB. thuringiensis, as determined by the diet incorporation bioassay method, was significantly lower for larvae infected transovarially withN. fumiferanae, but the similar slope obtained for initially healthy larvae indicated an independent and additive interaction. The median lethal time (LT50) forB. thuringiensiswas shortest for the group diseased withN. fumiferanae. Results from separate and sequential oral treatments (horizontal transmission) of both microorganisms at fixed physiological stages support the findings from the transovarial studies. It alsowas determined thatN. fumiferanae-free larvae survivingB. thuringiensistreatments were more susceptible to mortality from subsequent inoculations withN. fumiferanaethan were larvae not previously exposed toB. thuringiensis.

ISSN:1754-5692    

DOI:10.1093/ee/18.5.816

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

The two cynipid wasps,Diplolepis fusiformans(Ashmead) andD. spinosa(Ashmead), which induce galls on shoots ofRosa arizonicaRydberg, attack longer, more vigorous shoots with a higher probability than less vigorous shoots. Also, more adult insects emerge per gall on more vigorous shoots includingDiplolepis, the cynipid inquilinePericlistus, and parasitoids. This indicates that establishment in galls on vigorous shoots in relation to plant resistance is higher than on less vigorous shoots. However, the presence ofPericlistus, which makes multiple chambers perDiplolepishost, complicates an exact interpretation of the relative roles of plant resistance and natural enemies in the survivorship ofDiplolepisgallers. As ramets ofR. arizonicaage, mean shoot length declines, and attacks byDiplolepisare concentrated on young vigorous plants. The patterns of attack and establishment ofDiplolepisspecies are similar to those described for three species of tenthredinid sawfly gallers in the genusEuura. This study therefore contributes to an understanding that some herbivores require vigorous plants for successful use of resources, in contrast to arguments that herbivores survive best on stressed plants.

ISSN:1754-5692    

DOI:10.1093/ee/18.5.822

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Sequential sampling plans based on binomial distribution are presented for determining the need for measures to control tarnished plant bug,Lygus lineolaris(Palisot de Beauvois), in strawberry fields. Because no single theoretical distribution could describe data counts in every field, a double plan was developed by fitting the data to a regression equation. The equation related the mean number of nymphs per blossom cluster to the proportion of infested blossom clusters in the field. Four density classes were recognized: high (above the action threshold level of 0.25 nymphs per blossom cluster), medium, low, and very low. The sequential sampling plan with an action threshold of 0.25 nymphs per blossom cluster was compared with randomly tapping 100 blossom clusters and calculating an average count of nymphs per blossom cluster. In 100 different fields, the two techniques gave similar conclusions on 88% of occasions.

ISSN:1754-5692    

DOI:10.1093/ee/18.5.829

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Penetration and persistence of commercially formulated conidia ofBeauveria bassiana(Balsamo) Vuillimen in the profiles of long-term conventional and no-tillage plots were measured by recovery of colony-forming units (CFUs) at selected depths over 235 d after application of an aqueous spray of conidia to the soil. High percentages of fungal propagules recovered from the conventional and no-tillage plots remained in the upper 5 cm of the profiles of the Cecil sandy clay loam soil. The conidia (2–3 by 2.0–2.5 μm) apparently were filtered from the aqueous suspension by the soil matrix as the suspension passed through the soil profile. Penetration of small percentages of conidia to the depth of 10.1 to 15.0 cm in both tillage systems occurred before 8 h after application. Rate of penetration of propagules to these lower depths was faster in conventional plots than in no-tillage plots. Infiltration rates of water were consistent with the differential rate of penetration in the two systems. Although only 300 and 1,800 CFUs/cm3of dry soil remained in the 10.1- to 15.0-cm depth of the conventional and no-tillage plots, respectively, after 12 d, 90 and 75% ofGalleria mellonella(L.) larvae exposed to soil from this depth of the respective tillages were infected. Recovery of propagules from the 0- to 5-cm depth of the conventional and no-tillage plots decreased 95 and 86%, respectively, within 12 d of application of conidia. By day 235, the conventional tillage plot contained only 18 CFUs/cm3of dry soil at this depth. A 10-fold decrease in the number of CFUs remaining in the no-tillage plots occurred by day 49 (4.8 × 104CFUs/cm3of dry soil) with no propagules detected by day 200. Persistence of granular and wettable powder formulations ofB. bassianain the Cecil series soil was compared in a separate study. A 10-fold decrease in viable CFUs in plots treated with aqueous suspensions of the wettable powder occurred by day 21. By day 202, no CFUs remained in those plots. The number of CFUs recovered from plots treated with the granular formulation was 10 times higher than the number recovered from plots treated with the aqueous spray. After 202 d, 111 viable CFUs/cm3of dry soil remained in the plots treated with granular formulation.

ISSN:1754-5692    

DOI:10.1093/ee/18.5.835

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

Quantifying the presence of an edge effect in the distribution of gypsy moth,Lymantria dispar(L.) egg masses is important in sampling egg masses to determine unbiased population density estimates. Egg masses were counted on trees along the forest edge and on trees two chains (40.2 m) in from the forest edge in 16 locations in Virginia. Edge trees had about 2.4 times more egg masses than interior trees. The edge side of edge trees had about 3.2 times more egg masses than the edge side of interior trees and about 4.8 times more egg masses than the interior side of these same trees. Samples taken at or near the forest edge will overestimate population levels, or they will increase the probability of incorrectly classifying populations as being over thresholds if applied to larger areas using currently available sampling methods. In the areas studied, the edge effect on the distribution of egg masses is a function, in part, of the morphology of edge trees. The bias of an edge effect may not be a consideration when the edge area itself is the area of interest.

ISSN:1754-5692    

DOI:10.1093/ee/18.5.840

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

The trace element rubidium was used to mark adults and ova ofSpodoptera exigua(Hübner). Marked ova were produced by moths reared on rubidium-treated alfalfa and cotton and on an artificial diet containing rubidium, by females mated with rubidium-marked males, and by females exposed to plants sprayed with rubidium chloride. Decreasing levels of rubidium were found in ova produced by rubidium-marked females fed a sucrose diet containing potassium in a concentration similar to that found in cotton nectar. Increasing levels of rubidium were found in ova produced by previously unmarked female moths after mating with marked males or after exposure to cotton sprayed with rubidium.

ISSN:1754-5692    

DOI:10.1093/ee/18.5.844

出版商:Oxford University Press    

年代:1989

数据来源: OUP

摘要:

The relationship between density of elm leaf beetle,Xanthogaleruca luteola(Müller), and damage to English elm,Ulmus proceraSalisbury, and Siberian elm,Ulmus pumilaL., was studied in seven northern California cities in 1986 and 1987. Peak first-generation elm leaf beetle egg or larval densities were good predictors of cumulative foliage damage to English elm and to a lesser extent predicted Siberian elm damage. Egg density on both hosts was highly associated with the proportion of samples infested with eggs. The maximum proportion of presence-absence samples infested with first generation eggs predicted cumulative damage to English but not to Siberian elm. When no effort was made to control beetle populations most English elm trees sustained more than 40% damage to retained foliage, whereas damage to most Siberian elms was less.

ISSN:1754-5692    

DOI:10.1093/ee/18.5.849

出版商:Oxford University Press    

年代:1989

数据来源: OUP