摘要:

The causative agent of chalkbrood in the mason beeOsmia lignaria prop inquaCresson is a fungus recently namedAscosphaera torchioiYoussef&McManus. The present study was undertaken to devise a methodology to measure the infectivity potential of this fungus accurately, based on laboratory experiments designed to assure consumption of all spores by host larvae reared under nonstressful environments. Doses of 10, 100, 1,000, 10,000, and 100,000 spores per cell were tested, and the influence of temperature was measured by exposing replicate treatments to 20, 25, or 30°C. The levels ofA. torchioiinfection obtained in this study (0.36–8.5%) showed a linear correlation with increasing dose, and these low-level infections overlapped chalkbrood rates found in large field populations studied over a 15-yrperiod (0.4–2%). The infection rates reported in this study (0.36–8.5%) are, however, much lower than those induced in a recent series of related laboratory studies (57%). Causes for the large discrepancy of results obtained in this study versus results reported in earlier studies are attributed to previous experimental designs in which host larvae were reared in stressful environments, producing larvae of reduced vigor which resulted in enormous increases of chalkbrood mycosis.

DOI:10.1093/ee/21.5.1086

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Identifying the pollen attached to black cutworm,Agrotis ipsilon(Hufnagel), and armyworm,Pseudaletia unipuncta(Haworth), moths provided a powerful tool for recognizing food plants used by these noctuids before initiation of long-range movement. Pollen was found primarily on the proboscis and in decreasing frequency on the eyes, legs, and antennae. Fourteen moths collected in Iowa and Missouri were marked with the exotic pollensPithecellobiumspp. orCalliandraspp, or both. These plants are indigenous to southern climes, and the closest site of origin to the capture points is in southern Texas.From the closest plant location in Texas, these moths traveled 1,300km to central Missouri, 1,450 km to northern Missouri, and 1,600 km to central Iowa. Moths captured in March probably originated ≥600 km farther to the south than those captured in late April and May. Known exotic pollen was discovered on moths captured during May in Iowa, but these same pollens were found on moths captured earlier in Missouri. These results provided evidence of moth immigration into Missouri from within Mexico, possibly from the state of Tamaulipas.

DOI:10.1093/ee/21.5.1092

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Liriomyza sativaeBlanchard was the only agromyzid leafminer species reared from foliage of green onion,Allium cepaL. var.‘aggregatum’, collected at two commercial farms in the Waianae area of Oahu, HI. Mean weekly densities of live leafminers reached levels>13 larvae per leaf with mean seasonal densities of total mines as high as 20.6.In laboratory-conducted host plant-preference (choice and no-choice) tests, adult femaleL. sativaecolonized from the Waianae and Hawaii Kai areas of Oahu exhibited significantly greater host feeding and ovipositional preferences for foliage of ‘Henderson’ bush lima bean,Phaseoluslimensisvar.limenanusL. H. Bailey, compared to ‘multiplier’ onion. In no-choice tests, WaianaeL. sativaereared on onion and bush lima bean deposited significantly more eggs in onion compared with bean-reared Hawaii KaiL. sativae. However, when given a choice between onion and bean, preferences of bean-reared WaianaeL. sativaewere not significantly different from Hawaii KaiL. sativae. Onion-rearedL. sativaepreferred onion significantly more than bean-rearedL. sativaewhen provided a choice of the two host plants.Green onion has not been reported previously as a common host ofL. sativae. Based on differences in feeding and ovipositional preferences of WaianaeL. sativaecompared with Hawaii KaiL. sativae,it was concluded that Waianae populations ofL. sativaehad broadened their host range to include green onion. Factors conducive to host plant expansion ofL. sativaepopulations in the Waianae area of Oahu are discussed.

DOI:10.1093/ee/21.5.1097

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Response of Fraser fir,Abies fraseri(Pursh) Poiret, to the balsam woolly adelgid,Adelges piceae(Ratzeburg), was evaluated by studying wood cores and bark samples taken from six sites near Mount Rogers, VA, and five sites in the Black Mountains of North Carolina surrounding Mount Mitchell. For comparison, samples were also collected from silver fir,Abies albaMiller, at four sites in the Black Forest of Germany. AverageA. piceaedensities were higher on trees at Mount Rogers than on Mount Mitchell trees. Proportions of trees producing abnormal wood in response to low or moderateA. piceaedensities was greater for Mount Mitchell trees than for trees at Mount Rogers. Results from Mount Rogers support observations made for other fir species thatA. piceaeinfestation induces outer bark formation, leading to tree recovery. Outer bark formation in trees from the Black Mountains and the Black Forest of Germany was not correlated withA. piceaedensity. There was indirect evidence that the outer bark measured in Mount Mitchell trees was incompletely formed, with an indistinct boundary layer between living and nonliving bark layers.

DOI:10.1093/ee/21.5.1103

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Hatching and dispersal of early instars ofChilo partellus(Swinhoe) on maize were studied in the field at different initial densities. Approximately 20% of the larvae remained on the oviposition plant 1 wk after hatching. Dispersing larvae were about 25% of the original number of eggs. On average, 50% of the potential larvae (eggs) were lost within 14 d after oviposition. The mean number of plants infested from each oviposition plant varied from 2.26 to 4.22. The mean dispersal distance in the field for the larvae was ≈30–70 cm. Fewer new plants were infested by dispersing larvae as the initial density of egg batches increased; this may be due to competition for resources. No density dependence of mortality of egg and larvae due to natural enemies or other factors was demonstrated.

DOI:10.1093/ee/21.5.1110

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Soil samples were taken during dry and wet months from natural breeding habitats of phlebotomine sandflies in Marigat, Kenya. Soils were analyzed to determine chemical and physical factors; results were related to relative abundance of adult sand flies exiting from the same habitats. Soil pH, organic carbon, exchangeable cations, moisture content, sand, and silt showed differences between habitats during either the wet or dry season or both. Magnesium and clay did not differ between habitats. In burrows, no correlation was observed between sand flies of the generaPhlebotomusRondani&Berté andSergentomyiaFranca&Parrot and soil chemical and physical factors, whereas in termite mounds,Sergentomyiaspecies were negatively correlated with pH and phosphorus. In tree bases, contrasting highly negative and positive coefficients were observed between calcium, manganese, moisture, clay, andPhlebotomusspecies.Sergentomyiaspecies were positively correlated with organic carbon, potassium, and sand during the wet season; they were negatively correlated with pH and positively correlated with magnesium during the dry season. It is concluded that the abundance of sand flies depends to some extent on chemical and physical factors of their breeding places in the soil.

DOI:10.1093/ee/21.5.1114

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Tetradenia riparia(Hochst.) Codd. is a Rwandan traditional medicinal plant reported to be used to prevent postharvest insect damage in traditional storage. Addition of milled or crushed leaves ofT. ripariaat ≥4% (wt/wt) significantly decreased fecundity and fertility ofZabrotes subfasciatus(Boheman) andAcanthoscelides obtectus(Say), which resulted in smaller F1 populations. A concentration of 10% leaves (wt/wt) also increased cumulative larval and pupal mortality forZ. subfasciatus. The increased mortality may be caused by increased competition betweenZ. subfasciatuslarvae within the bean. Competition could be influenced by the great decrease in percentage of beans oviposited upon byZ. subfasciatus.The control achieved against the F1populations did not persist. Hormoligosis, in the form of increased fecundity, was also found for leaves from one supply at the 1% concentration. In general, the initial inhibitory effects were found to be reproducible using different supplies of leaves. Results were also quite consistent for the two species of Bruchidae, despite innate behavioral differences between them at oviposition and hatch.

DOI:10.1093/ee/21.5.1121

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Nerolic acid, the second most abundant compound in the Nasonov pheromone of the honey bee,Apis melliferaL., was investigated to determine its importance as a component in synthetic attractants for honey bees of Africanized and European populations. Both populations of bees preferred synthetic pheromone blends containing nerolic acid in combination with citral and geraniol to those containing only citral and geraniol. These findings indicate that honey bee swarms of both Africanized and European populations recognize and respond in the same manner to synthetic Nasonov pheromone, and that nerolic acid exerts an important synergistic effect on the attractiveness of other Nasonov components. Nest cavity shape, tapered cylinder versus rectangular prism, apparently is not an important factor in cavity acceptance by honey bee swarms.

DOI:10.1093/ee/21.5.1130

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Laboratory studies of diapause induction in the horn fly,Haematobia irritans irritans(L.), revealed that maternal photoperiod had no influence on the time of emergence of nondiapausing or diapausing horn flies. Larval rearing temperature affected emergence time of nondiapausing horn flies, but had little effect on emergence time of diapausing horn flies. Horn flies began emerging from diapause at 25°C after 60 d exposure to temperatures below 20°C. Emergence from diapause required<60 d at 25°C for completion. Diapause occurred in nearly 100% of insects reared at less than 16°C regardless of photoperiod to which the parents were exposed. No diapause occurred in insects reared at 25°C, regardless of whether the parents were exposed to 8, 12, or 16 h light. Intermediate levels of diapause occurred in insects reared at 20°C, but this showed no relationship to maternal photoperiod. Overall, larval rearing temperatures accounted for 89.2% of the variation in the incidence of diapause, while maternal photoperiod alone accounted for only 0.1%.

DOI:10.1093/ee/21.5.1134

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Temperature-dependent development in a ladybeetle,Eriopis connexaMulsant, was determined at seven constant temperatures between 10 and 34°C. Egg hatch at 10°C was 0% after 75 days. Egg hatch at temperatures between 14 and 26°C averaged 67%, and 43% of the eggs hatched at 30 and 34°C. None of the larvae developed into pupae at 10°C. Larval mortality was 33.1% at 14°C and ranged between 3.6 and 17.7% at 18–34°C. Development from oviposition to adult ranged from 53.3 days at 14°C to 10.9 days at 34°C. Lower developmental thresholds were 9.5, 9.9, and 5.9°C for eggs, larvae, and pupae, respectively. Overall, heat-unit requirements for development from egg to adult were 259.1 degree-days above a developmental threshold of 9.2°C. The ability ofE. connexato develop at relatively cool temperatures is discussed in a comparison with other temperate aphidophagous coccinellids.

DOI:10.1093/ee/21.5.1139

出版商:Oxford University Press    

年代:1992

数据来源: OUP