摘要:

An understanding of the physical characteristics of a leaf is necessary in feeding behavior studies of phytophagous insects. A penetrometer based on a strain gauge transducer, miniature lathe, and recorder readout was devised to measure leaf toughness. Details of its construction and use are reported.

ISSN:1754-5692    

DOI:10.1093/ee/5.2.291

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

Twenty-two alfalfa clones were evaluated for potato leafhopper,Empoasca fabae(Harris), resistance by infesting excised plant parts with adult leafhoppers in a controlled environment. Field ratings for yellowing and laboratory ratings for yellowing and wilting correlated significantly. Leafhopper yellowing in the field and nymphs/gram of dry plant material did not correlate. Clonal preferences were displayed in both the field and laboratory, but the ratings did not correlate.Excised parts from plants in the field provided a more reliable assessment of resistance than did similar parts from plants growing in a greenhouse. Clonal yellowing and wilting of excised terminals from field grown plants were correlated highly (r=0.91**) with yellowing in the field. Excised stem terminals from plants growing in a green-house were less resistant to both adult and nymphal leafhopper feeding than were terminals from plants grown in the field.

ISSN:1754-5692    

DOI:10.1093/ee/5.2.295

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

The nuclear-polyhedrosis virus ofTrichoplusia ni(Hübner) (T. niNPV) and the granulosis virus ofPieris rapae(L.) (P. rapaeGV) added to shredded cabbage before sauerkraut fermentation were at least 75% inactivated during fermentation.T. niNPV andP. rapaeGV added after fermentation were inactivated by pasteurization of the fermented sauerkraut.Bacillus thuringiensiswas not inactivated during fermentation and was only partially inactivated by pasteurization of fermented sauerkraut.The small quantities of the viruses found in nontreated shredded cabbage were inactivated during sauerkraut fermentation.

ISSN:1754-5692    

DOI:10.1093/ee/5.2.302

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

Two major components of the sex pheromone of the clover cutworm moth,Scotogramma trifolii(Rott.), have been isolated from an extract of ♀ abdominal tips and identified by gas chromatography and mass spectrometry as (Z)-11-hexadecen-1-ol and its acetate. Electroantennogram data agreed with the assignment of (Z)-11- for the alcohol and acetate. Both (Z)-11-hexadecenyl alcohol and (Z)-22-hexadecenyl acetate were found to be obligatory for effective field trapping of ♂ moths. Ratios of alcohol: acetate between 1:1 and 1:9 gave good capture rates with the higher ratios being somewhat more effective than lower ones.

ISSN:1754-5692    

DOI:10.1093/ee/5.2.307

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

The influence of parasitism byMicroctonus aethiops(Nees) (Hymenoptera: Braconidae) on the susceptibility of its primary host, the alfalfa weevil,Hypera postica(Gyllenhal) to carbofuran (Furadan®), methoxychlor, methyl parathion and Supracide® was studied in the laboratory. Relative toxicities to the adult and pupal stages of the parasite were also determined.Furadan was the most toxic compound to nonparasitized weevils with an LD50of 1.18 μg/g body wt, followed by methyl parathion, Supracide and methoxychlor. Methoxychlor was about 3000 times less toxic than Furadan.Parasite egg development in the host did not influence weevil susceptibility. However, parasite larval development increased host susceptibility and the LD50values decreased by almost one-half.Supracide, Furadan, methyl parathion and methoxychlor were ca. 2, 3, 5 and 600 times more toxic to adult parasites than to adult weevils.Parasite pupae displayed considerable resistance. Furadan and methyl parathion were about 90 times less toxic to pupae than to adults. Similarly, Supracide and methoxychlor toxicity decreased 54- and 17-fold, respectively.

ISSN:1754-5692    

DOI:10.1093/ee/5.2.311

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

The phenology of bud burst and shoot elongation of the host tree and egg hatch and larval development were studied on 3 areas in a 1972 infestation. Bud burst and egg hatch were found to be closely related to accumulated degree-days, and peak egg hatch occurred when 77–97% of the buds had burst. Larval development then closely followed shoot elongation. This synchrony of host and insect phenology provides an easily observed field event for monitoring Douglas-fir tussock moth development.

ISSN:1754-5692    

DOI:10.1093/ee/5.2.316

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

In laboratory studies,Copidosoma truncatellum(Dalman), a polyembryonic encyrtid that is an egg-larval parasite ofTrichoplusia ni(Hübner), was found to parasitize any age of egg. AlthoughC. truncatellumwas not an effective searcher of host eggs, even in a confined area, freshly emerged parasites showed a greater rate of parasitization than older (24-h) parasites even though both had a full complement of eggs. The parasite usually injects more than 1 egg into the host at a single insertion of the ovipositor. Temperature affects the rate of parasitization, the time taken for oviposition, and the percentage of brood that will oviposit. The parasite contains a full complement of eggs at adult emergence, which diminishes only with use; eggs are not reabsorbed. Not all individual females in a single brood are functionally fecund; many never oviposit even though they contain eggs. Those that will oviposit, oviposit most eggs early; by the middle of the adult lifespan, they have laid the final egg, and the last half of the adult lifespan is essentially nonfunctional. At certain temperatures, the parasite causes some mortality of host eggs and larvae before the 5th stage; such deaths also kill the contained parasites.

ISSN:1754-5692    

DOI:10.1093/ee/5.2.323

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

When parasitized house fly pupae were placed at 8 different constant temperatures in the laboratory, the parasitoidSpalangia endiusWalker, failed to develop completely at 12.8 and 15.6°C. The length of successful development ranged from 66 days at 18° to 17 days at 35°C. Another fly parasitoid,Muscidifurax raptorGirault and Sanders, failed to complete its development at 12.8 and 35°C, but generally developed faster thanS. endius.Under field conditions, parasitoid developmental rates varied on a seasonal basis and ranged between 21 and 183 days forS. endiusand from 19–126 days forM. raptor. Developmental rates of both species were similar during summer, butM. raptordeveloped at a significantly faster rate during cooler months.An algorithm was used to predict development of parasitoids by providing simulation of responses to constant and variable temperatures. High correlation coefficients between predicted and observed developmental rates were obtained with both parasitoid species.

ISSN:1754-5692    

DOI:10.1093/ee/5.2.329

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

Races B, C, D, and Great Plains of the Hessian fly,Mayetiola destructor(Say), were used to infest wheat cultivars Seneca, Monon, Knox 62, and Arthur 71, all of which have different genes for resistance. The cultivars were grown in standard green-house flats and placed in chambers at 15, 18, 21, 24, or 27+1°C. Results showed that cultivars with different specific genes for resistance grown at several temperatures react differently when infested by various races of Hessian fly. Most of the resistant cultivars showed an increase in infestation and tillering as temperatures were increased. However, tillering varied depending on the race, the cultivar, and the temperature used. High tillering could potentially be an important form of tolerance in some cultivars helping to offset some of the losses caused by the Hessian fly.We propose that a constant temperature of 27°C be considered as a screening tool to aid entomologists and plant breeders in selecting resistant wheat cultivars that are stable to Hessian fiy infestations at high temperatures.

ISSN:1754-5692    

DOI:10.1093/ee/5.2.333

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

The distributional patterns ofStethorus punctum(LeConte) in relation to densities of the European red mite,Panonychus ulmi(Koch), were investigated within an apple orchard and within an apple tree.S. punctumadults have the ability to find increasing mite populations on trees in an orchard. A prey population averaging 2–3 motile mites/leaf is sufficient to enable the predator population to reproduce and increase in size. Temperature was found to influence the ability ofS. punctumto find its prey. Within the tree, distribution showed thatS. punctumadults search out areas of the tree where the mite populations were the highest.S. punctumlarvae also were found feeding in these areas. Mite populations increased within the row where the leaves were not as heavily hit by spray.

ISSN:1754-5692    

DOI:10.1093/ee/5.2.337

出版商:Oxford University Press    

年代:1976

数据来源: OUP