摘要:

Tests conducted in a large field cage demonstrated that the tachinid,Lixophaga diatraeae(Townsend), were attracted to sections of the cage containing sugarcane infested with the larvae of the parasites host, the sugarcane borer,Diatraea saccharalis. Within sections of the cage, the parasites were able to distinguish between adjacent infested and uninfested plants. Further testing indicated that interactions between the host and its food plant are the source of attraction to larvipositing females.Larviposition byL. diatraeaeon sugarcane stalks was significantly reduced at host feeding sites where larviposition and subsequent parasitization had occurred 24 h previously. This may prevent multiple parasitization of unsuitable hosts, thus conserving maggots.

ISSN:1754-5692    

DOI:10.1093/ee/11.2.273

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

Navel orangeworm damage to pistachio nuts was especially severe in portions of an orchard adjacent to blocks of infested almonds which served as the sources of immigrant moths. The degree of damage diminished as distance from the principal external sources of moths increased, reaching economically unimportant levels at ca. 500 m. Pest management programs for the navel orangeworm in pistachios should include reduction efforts in almonds when almonds border pistachio orchards.

ISSN:1754-5692    

DOI:10.1093/ee/11.2.278

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

Up to seven times as many eggs of the navel orangeworm were laid on oviposition traps containing navel orangeworm-infested mummy almonds as on traps containing uninfested mummies. Frass along with other insect-produced debris from mummy nuts was highly attractive and resulted in increased visitation by adults of both sexes and in increased oviposition, showing that a larval-to-adult communication system exists. Whether this involves a pheromone remains to be established. An ether extract of insect-derived debris (mostly frass) from mummy nuts was shown both to attract and to stimulate oviposition by female moths.

ISSN:1754-5692    

DOI:10.1093/ee/11.2.280

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

Three adult corn rootworm sampling techniques were employed in 59 Iowa cornfields during August 1976 and 1977. Northern and western corn rootworm beetle counts were analyzed by Green's coefficient, Cx, and Iwao's regression method, m*=a+bm, to determine spatial dispersion patterns. Both indices indicated that most rootworm beetle populations sampled were characterized by aggregated dispersion. Spatial behavior in rootworm beetles tended to be density dependent. Some populations with large mean densities, however, did not differ significantly from randomness.

ISSN:1754-5692    

DOI:10.1093/ee/11.2.283

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

Sample sizes were determined for three adult corn rootworm sampling techniques. Sources of variation in the sampling plan used were analyzed with a nested analysis of variance. Plant-to-plant, ear-to-ear, and trap-to-trap variation accounted for the greatest percentage a variability, on a within-field basis, in their respective analyses. Optimum allocations of sample units were two plants per site, five ears per site, and one trap per site. Comparisons of precision and cost of the three methods revealed that plant counts provide the most precise estimate of beetle populations for the least cost.

ISSN:1754-5692    

DOI:10.1093/ee/11.2.287

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

The algaChlorella ellipsoideaGerneck caused 85% reduction in the populations of mosquitoes breeding in cemetery vases. Annual mean larval densities of 9 and 61 larvae per vase were observed in algal and nonalgal vases, respectively. The maximum mean larval density of 17 larvae per vase in algal vases was significantly lower than the corresponding maximum (131 larvae per vase) in the nonalgal vases. The low numbers of mosquito larvae prevailing in the algal vases were likely due to the action of toxins produced byC. ellipsoidea. Lower larval densities, “0” and “1–10” larvae per vase, were found in 57 and 24% of the algal vases, respectively, whereas these densities occurred in 22 and 12%, respectively, of the nonalgal vases. The percentages of nonalgal vases supporting the three higher densities (26–50, 51–100, and>100 larvae per vase) were significantly higher than those of the algal vases.The number of vases with and without algae supporting first- and second-stage larvae was similar, however, the number of vases supporting third- and fourth-stage larvae and pupae was significantly higher in the nonalgal than in the algal vases. The percentage of algal vases containing dead larvae or pupae was significantly higher (ca. 11 times) than that of the nonalgal vases.Studies on algal growth revealed that an overall average of 23% of the vases containedC. ellipsoideaduring the study period. The incidence of this alga peaked during May (33% vases with algae) and was lowest in December (7%). No apparent relationship between algal density and mosquito numbers was observed.

ISSN:1754-5692    

DOI:10.1093/ee/11.2.292

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

The feeding patterns of Australian and North AmericanHeliothisspecies on cotton are very similar. Field observations show that the later stages of larvae fed selectively on older fruit. In addition, there was a seasonal change which can be accounted to the shift in available fruit to the older age classes. AlthoughH. punctigeraandH. armigeraare considered to prefer terminals and squares, and bolls, respectively, differences between them in feeding patterns can for the most part be attributed to the change in abundance of fruit in each age class as the season progresses.Heliothislarval feeding information has proven useful in simulation modeling of cotton-Heliothisinteractions and is essential for assessing the relevance of currentHeliothisthresholds.

ISSN:1754-5692    

DOI:10.1093/ee/11.2.297

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

Terminal damage to cotton,Gossypium hirsutumL., causes an initial decrease in growth and fruit development. This decrease appears to be less when damage occurs later in the growth period. Terminal damage does not change the relative allocation of nutrients to the roots, stems, leaves, or fruit; nor does it reduce the number of bolls when the season length is sufficient for compensation to occur.

ISSN:1754-5692    

DOI:10.1093/ee/11.2.301

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

The association of strong southerly winds with first spring captures of black cutworm (BCW),Agrotis ipsilon(Hüfnagel), adults in blacklight traps and captures of male BCW in traps baited with 40 μg of synthetic pheromone (3:1 ratio of Z-7-dodecanyl acetate:Z-9-tetradecanyl acetate) indicates that the first flight of BCW moths immigrate to central Iowa. This hypothesis is supported by the fact that all captured first-flight females are mated, a condition often associated with immigrating females. Additionally, a BCW development simulation model demonstrated the potential existence of two separate BCW populations, i.e., (1) immigrants and progeny, and (2) natives and progeny. We attribute low pheromone trap captures of BCW males and blacklight trap captures of mostly unmated females during the autumn flight to reproductive diapause in one or both sexes. We hypothesize further that a reproductive diapause might portend an autumnal southward migratory flight of BCW from Iowa.

ISSN:1754-5692    

DOI:10.1093/ee/11.2.306

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

Both temperature and time of day influence the occurrences and frequencies of major types of ventilation inErythemis simplicicollisnaiads. Between 16 and 32°C, frequency of normal ventilation is linearly related to the temperature of an individual's ambient environment. Under constant temperature conditions, frequencies of normal ventilation are rhythmic within the diel: highest during photophase and lowest during skotophase. Gulping ventilation occurs more frequently at higher acclimation temperatures.

ISSN:1754-5692    

DOI:10.1093/ee/11.2.313

出版商:Oxford University Press    

年代:1982

数据来源: OUP