摘要:

Beauveria bassiana(Balsamo) Vuillimen has been identified as a naturally occurring pathogen of larval lesser cornstalk borer,Elasmopalpus lignosellus(Zeller). Studies were conducted to determine the effects of a commercialB. bassianaspore preparation (ABG-6178, Abbott Laboratories) on larvae ofE. lignosellus. B. bassianawas virulent to first and third instars in bioassays in which inoculum was applied to leaf substrates. First instars were more susceptible than third instars. Larvae treated withB. bassianacontinued to develop and consume food at normal rates until they died or pupated. Higher conidial levels were required to cause mortality when inoculum was mixed into the larval soil habitat. Sterilizing soil before bioassaying resulted in a 10- and 1,000-fold reduction in LC50values required to kill first and third instars, respectively.

ISSN:0046-225X    

DOI:10.1093/ee/19.1.137

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Host-finding oviposition behavior ofAnagrus mutansWalker andAnagrus silwoodensisWalker are similar when attacking eitherCicadella viridis(L.) orDicranotopis hamata(Boheman). Antennae play an important role in finding hosts and orienting the female on top of the host egg.A. mutanswas slower handling hosts thanA. silwoodensis. Parasitoids reared fromC. viridiswere larger and handled hosts more slowly than parasitoids reared fromD. hamata. Mean times for drilling and initial oviposition inC. viridisandD. hamatawere 32.6 and 64.3 s, respectively, forA. mutansreared fromC. viridisand 34.5 and 56.1 s, respectively, forA. silwoodensisreared fromC. viridis. BothAnagrusspecies rejected parasitized hosts. Rejection always followed drilling. When smallerD. hamatawere attacked, bothAnagrusspecies completely avoided oviposition in a parasitized host. However, when the largerC. viridishosts were attacked, the degree of avoidance varied, andA. silwoodensismore consistently avoided subsequent ovipositions. Rejection of an already parasitized host byA. silwoodensisoccurred as early as 30 s;A. mutansoviposited in hosts up to 15 min after the first attack.

ISSN:0046-225X    

DOI:10.1093/ee/19.1.142

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Predation by the ant,Solenopsis geminata(F.), on fallingCeratitis capitata(Wiedemann) larvae in the field ranged from 7 to 25% in coffee and orange orchards. The ant population estimated by two sampling methods was higher in orange orchards than in the coffee orchard. Seasonal change did not affect ant predation on pupae, but the seasonal temperature and the time of the day had a significant effect on predation on larvae by the ants. Indications were that unless the periodicity of emergence of larvae from the fruit coincides with the activity of ants, the predation on pupae by ants or other insects may be higher than on larvae.

ISSN:0046-225X    

DOI:10.1093/ee/19.1.148

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Grain sorghum panicles were collected and examined forHeliothis zea(Boddie) eggs and larvae andCelama sorghiella(Riley) eggs during 1986–1988 in seven sorghum fields along the Red River in southwestern Arkansas, northeastern Texas, and southeastern Oklahoma.Trichogramma exiguum(Pinto and Planter) andT. pretiosumRiley were the predominant parasites attackingH. zeaandC. sorghiella eggs. Trichogrammaspp. appeared to be an important mortality factor ofH. zeaandC. sorghiellaeggs on grain sorghum panicles, particularly ifH. zeaorC. sorghiellaeggs were available through the season forTrichogrammaspp. to build up on. Seven species of parasites were reared fromH. zealarvae; one eulophid, three tachinids, and three braconids. The incidence of larval parasitism was low, less than 2%, for the three-year study and appeared to have a minimal effect on larval numbers.

ISSN:0046-225X    

DOI:10.1093/ee/19.1.154

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Larvae of the stalk borer,Papaipema nebris(Guenée), collected from corn, potatoes, and giant and common ragweed in northern Ohio were reared to pupation to determine parasitism. Parasitoid complexes were dominated byLixophaga thoracica(Curran) (Tachinidae) in corn (78.3% of the total parasitoids);Sympiesis viridula(Thompson) (Eulophidae), an introduced parasitoid of European corn borer,Ostrinia nubilalis(Hübner), in potatoes and associated common ragweed (62.9%); andLissonata brunnea(Cresson) (Ichneumonidae) andGymnochaeta ruficornisWilliston (Tachinidae) in giant ragweed (96.3%). Percentage of parasitism byG. ruficorniswas positively correlated with stalk borer density; withL. brunneathe correlation was negative. This study demonstrates the importance of host habitat for several parasitoids of the stalk borer.

ISSN:0046-225X    

DOI:10.1093/ee/19.1.162

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Rate of response to selection forNephotettix virescens(Distant) virulence was studied for 20 generations on five rice cultivars with different levels of resistance. Rate of response to selection on all cultivars varied depending on the measurement criteria. Survival, growth, progeny production, and weight increased, and developmental period decreased, with selection time. Based on survival, theN. virescenspopulation became highly virulent within one to four generations, whereas high virulence as measured by progeny production generally required more generations of selection. Virulence as measured by the ability to vector tungro virus also increased with selection time.

ISSN:0046-225X    

DOI:10.1093/ee/19.1.167

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Under field conditions, densities of 0, 4, or 8 adult female potato leafhoppers,Empoasca fabae(Harris), were caged on individual alfalfa plants during the second and second-third crop growth cycles. Plants were destructively sampled three times in each crop growth cycle. Injury byE. fabaecaused the percentage of total nonstructural carbohydrates to be much higher in leaves of infested plants. Leaf photosynthesis of plants caged with 4 or 8E. fabaewas reduced by 60 and 80%, respectively. The effects of feeding byE. fabaeon leaf transpiration were very similar to that shown for photosynthesis. Stomatal resistance increased from11 s cm−1on infested plants. Leaf crude protein of plants infested with either 4 or 8E. fabaewas reduced by 22–35% after only 1 wk of leafhopper feeding.

ISSN:0046-225X    

DOI:10.1093/ee/19.1.176

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

A starch formulation ofBacillus thuringiensisBerliner is being developed as a component in a pest management system to controlOstrinia nubilalis(Hübner). Palatability is one property of starch formulations which must be investigated; this study was done to identify materials that will causeO. nubilalislarvae to feed readily on starch granules. A two-choice behavioral bioassay was developed for evaluating phagostimulants in starch granules (withoutB. thuringiensis). Various materials were tested: compounds reported in the literature as feeding stimulants, the artificial diet for the species, corn foliage. corn oil, and the commercial feeding stimulant, Coax. Starch granules without additives were seldom fed upon by larvae, but it was possible to make the granules even more acceptable to larvae than corn foliage. The best feeding responses were to mixtures containing lipid, sugar, and protein. Coax was the most effective material tried; for example, in bioassays, the ratio of larvae that chose granules with Coax over those with only starch was 320:1, and the ratio of larvae choosing granules with Coax over corn leaf disks was 11.5:1. In greenhouse tests, phagostimulants increased the effectiveness of granules containingB. thuringiensisfor killingO. nubilalislarvae. For example, when Coax was added to the granules, the amount ofB. thuringiensisused could be reduced by 75% without reducing mortality.

ISSN:0046-225X    

DOI:10.1093/ee/19.1.182

出版商:Oxford University Press    

年代:1990

数据来源: OUP

ISSN:0046-225X    

DOI:10.1093/ee/19.1.190

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Deep appreciation is extended to those who gave so generously of their time to review manuscripts forEnvironmental Entomologyin 1989.

ISSN:0046-225X    

DOI:10.1093/ee/19.1.191

出版商:Oxford University Press    

年代:1990

数据来源: OUP