摘要:

Susceptibility to the maize weevil,Sitophilus zeamaisMotschulsky, of corn lines bred for their resistance to the aflatoxin-producing fungusAspergillus flavusLink ex Frics was determined in the laboratory. Duration of maize weevil development, number of progeny produced, and an index of susceptibility varied with corn line; number of eggs laid and survivorship from egg to adult emergence did not vary with corn line. Soluble carbohydrate, kernel hardness, lipid, soluble nitrogen, free and bound phenolic acids, Kjeldahl protein, and protein/carbohydrate ratio varied with corn line; equilibrium moisture content did not vary with corn line. The only relationship between biological parameters of maize weevils and chemical lild physical properties of the stored corn that was predictable was that maize weevil development time increased as lipid content of the corn increased. Susceptibility toA. flavusinfection in the field was not correlated with susceptibility to maize weevil population growth or with chemical or physical properties of the stored corn. Predicted weevil population growth over a 180-d period varied 50-fold among the corn lines. Some of the corn lines that are less susceptible to infection byA. flavusin the field were also less susceptible to maize weevils (particularly Mp420 and SC54).

DOI:10.1093/ee/24.4.944

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

The Old World parasitesCotesia chilonisandC. flavipeswere compared for survival, parasitization, and utilization of the New World hostDiatraea saccharalis. Parasite cultures consisted of one collection ofC. chilonisfrom Japan and three collections ofC. flavipes, two temporally separate collections from the Rio Grande Valley of Texas, and a collection from Thailand. Adult females kept without food or water lived an average of 20.3 h and did not differ among parasite cultures. Egg-larval development averaged 13.1 d and did not differ among the cultures. Pupal development averaged 6.5 d forC. chilonis, 7.6 d for the two TexasC. flavipescultures, and 8.5 d for the ThaiC. flavipesculture. Numbers of progeny per parasitized host ranged from 73.9 for one TexasC. flavipesculture to 36.7 forC. chilonis. TheC. chilonisculture successfully parasitized 76% of hosts, versus 52 and 57% for the two Texas cultures, and 30% for the Thai culture. Seventy-nine of the 800D. saccharalishosts exposed to parasites encapsulated parasite progeny, as evidenced by a localized, dark spot on the posterior dorsum of host larvae. The magnitude of encapsulation differed greatly among cultures. Only one host exposed toC. chilonisencapsulated parasites (0.5%), whereas the threeC. flavipescultures averaged 13% of hosts that encapsulated the parasites. Host larvae exhibiting the characteristic dark spot had several outcomes: delayed complete or partial host pupation (22%): hosts remained in a terminal larval stage (50%): or hosts produced a few parasite progeny (28%). Few differences were found between the two parasite collections from Texas that differed only in the duration of time in culture. However, the results suggested biological differences amongC. chilonis, the Thai collection, and the two collections ofC. flavipesfrom Texas.

DOI:10.1093/ee/24.4.950

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Isolates ofPandora neoaphidis(Remaudière&Hennebert) Humber from field collections in Kentucky (KY)and North Carolina (NC) were subjected to various temperature and humidity regimes to evaluate sporulation plasticity. Greatest conidial production occurred at 10–25°C and 100% RH or in free water. No conidia were produced at 30°C or below 98% RH. The optimal temperature for in vitro growth of the 2 isolates on modified egg-milk-agar media was 15°C. The NC isolate was more virulent than the KY isolate against tobacco aphid,Myzus nicotianaeBlackman, collected from the Lexington, KY, site. Alatae were more susceptible to P. neoaphidis than apterae when exposed to the same source of inoculum at 23°C, 100% RH, and a photoperiod of 16:8 (L:D) h. Conidia produced in vitro by both isolates, when showered onto tobacco leaf disks, were infectious toM. nicotianaefor at least 35 h at 100% RH and 23°C.

DOI:10.1093/ee/24.4.962

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Three European biological control agents of the exotic, wetland, perennial plant purple loosestrife,Lythrum salicariaL., were released in North America in 1992 and 1993. Two leaf-feeding beetles,Galerucella calmariensisL. andG. pusillaDuftschmidt, from 2 climatically different source populations in Germany, were released in 10 different states and 6 Canadian provinces. The importance for establishment success of climatic preadaptation, number of individuals released, release of laboratory or field-collected material, and confinement of release were investigated in a series of experimental releases. BothGalerucellaspecies became established at all 1992 release sites regardless of their origin or release method. Higher survival in cages was found for releases of 600 beetles compared with releases of 200 beetles. The amount of litter, number of standing dead stems, or host-plant density clid not affect establishment. A root-feeding weevil,Hylobius transversovittatusGoeze, was released in 9 states and 2 Canadian provinces, and established in the field in 6 states and both provinces. The 3 species successfully passed the most critical phase for establishment in North America; production of the generation following release.

DOI:10.1093/ee/24.4.967

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Four cereal stemborers occurring in Kenya,Chilo partellus(Swinhoe),Chilo orichalcociliellusStrand (Lepidoptera:Pyralidae),Busseola fusca(Fuller), andSesamia calamistisHampson (Lepidoptera: Noctuidae),were exposed to females of the larval endoparasitoidsCotesia flavipesCameron andCotesia sesamiae(Cameron) to assess their acceptability for oviposition and suitability for development of the parasitoids. There was no difference in the acceptability of the 4 hosts exposed toCotesia flavipes. In contrast,Cotesia sesamiaepreferredS. calamistislarvae, followed by the 2 Chilo species;B. fuscalarvae were the least attacked byCotesia sesamiae. The suitability of the 4 hosts also varied with the parasitoid species. Neither parasitoid species developedinB. fuscaand egg encapsulation was observed. BothChilospecies andS. calamistiswere suitable hosts for the development ofCotesia flavipes. However, higher immature mortality was observed inS. calamististhan inChilo partellus. There were no differences in the mean number of progeny per female or the sex ratio. The most suitable host forCotesia sesamiaewasS. calamistis, followed by the 2Chilospecies which were equally suitable. When 3rd, 4th, 5th, and 6th instars ofChilo partelluswere exposed toCotesia flavipesfemales, immature parasitoid mortalitywas highest in 3rd-instar hosts.

DOI:10.1093/ee/24.4.978

出版商:Oxford University Press    

年代:1995

数据来源: OUP

DOI:10.1093/ee/24.4.985

出版商:Oxford University Press    

年代:1995

数据来源: OUP