摘要:

Samples of fall armyworm,Spodoptera frugiperda(J. E. Smith), were collected from cornfields near St. Gabriel, La., in 1981 and 1982, and near Hammond, La., in 1982 and 1983. Prevalence of a nuclear polyhedrosis virus (NPV) was<15% at the St. Gabriel site, but exceeded 40% at Hammond. Multiple regression analysis indicated that host population factors affected prevalence of NPV at St. Gabriel, and that abiotic factors were more important at Hammond. Medium-sized larvae (third and fourth instars) were more commonly infected than small (first and second instars) or large (fifth and sixth instars) larvae. Disease did not appear sustainable in a population until a threshold density of approximately one larva per corn plant was attained.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.260

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Three varieties of rice (Oryza sativaL.) in the USDA World Collection were selected as potential sources of host plant resistance to the Angoumois grain moth,Sitotroga cerealella(Olivier) and crossed with the susceptible commercial cv. Vista. The resistant varieties were ‘Mutica’ (CI 12273), PI 160849, and CI 7097. The crosses were evaluated through three or five generations for resistance to the Angoumois grain moth and lesser grain borer,Rhyzopertha dominica(F.) in no-choice tests. In addition to these two species, rice weevil,Sitophilus oryzae(L.), red flour beetle,Tribolium castaneum(Herbst), andCryptolestesspp. were included in free-choice tests. Two crosses were studied through the F3generation. The cross with the most promising resistant parent (‘Mutica’) was studied through the F5generation. In all cases, resistance was heritable (i.e., insect response in one generation tended to predict a similar response in the next generation). This tendency grew stronger as plants selected for resistance or susceptibility over several successive generations became more homozygous. Resistance to the Angoumois grain moth strongly predicted resistance to the lesser grain borer. The main criterion used to evaluate resistance was insect survival from larva to adult. This was related to the condition of the hulls, but the Angoumois grain moth generally required longer to develop on resistant lines than on susceptible ones.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.268

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The development of corn earworm,Heliothis zea, populations on corn was investigated in the Lower Rio Grande Valley of Texas and Tamaulipas, Mexico, during 1985 and 1986. Initial infestations by small larvae of 42.8 and 19.8% on whorl stage corn occurred during the weeks ending on day 102 (12 April) of 1985 and day 95 (5 April) of 1986, respectively. Initial trap peaks of 108 males/trap (1985) and 61 males/trap (1986) occurred from 4 d before to 3 d after the initial estimated oviposition peaks. Adults from larvae developing on whorl stage corn produced the infestation on fruiting corn during the weeks ending on days 130–137 and resulted in the largest trap peak of the year (132 males/trap in 1985 and 289 males/trap in 1986). Midpeak of trap capture occurred 9–12 d after the oviposition peak on fruiting corn. Adult emergence in fruiting corn occurred between days 150 and 182 and averaged 3.0 and 0.80/m2respectively for 1985 and 1986. The lack of a major trap peak associated with this emergence indicates that a major portion of these adults migrated from the area before mating.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.274

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Flight initiation in postdiapause Colorado potato beetles,Lepttnotarsa decemlineata(Say), occurred at temperatures as low as 15°C in field trials, and the percentage of initiation increased gradually to 100% at 20°c.Flight initiation and behavior were different between starved and fed beetles; starved beetles initiated more flights to greater heights and over longer distances. In wind tunnel studies, flight initiation increased with increasing light intensity.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.281

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The immature stages ofAtrichopogon wirthiChan and Linley are found mostly on the lower surfaces of more mature leaves of the water lettuce,Pistia stratiotesL. Eggs, first instars, and pupae are found only on the leaf undersurface, while second to fourth instars may occur also on top of the leaf. Eggs are laid mostly in the large undersurface grooves 1–11 cm above the wet–dry line (most from 5–10 cm). First instars are found close to the eggs, on the distal third of the leaf. Second instars are more widely distributed, with the majority situated around or just above the wet–dry line, and with occasional individuals 1–10 cm above it. Third and fourth instars also occur mainly around the wet–dry line (0.5 cm below to 4 cm above). Pupae are distributed more distally, 3–9 cm above the wet–dry line.Pistiaplants examined between July and October 1987 yielded an average of 28.3 unhatched (presumably viable) eggs, 4.5 first, 2.5 second, 1.8 third, and 2.4 fourth instars, 2.3 pupae, and 2.8 pupal exuviae per plant. Certain inferences concerning the life history and behavior ofA. wirthiare discussed

ISSN:1754-5692    

DOI:10.1093/ee/19.2.286

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The influence of various environmental factors on flight activity ofWinthemia fumiferanaeTothill (Diptera: Tachinidae) was studied in southern Québec from 1985 to 1987. Adults of both sexes were strictly diurnal and much more active in the presence of sunlight. Flight activity was positively related to maximum air temperature above 15°C and, to a much lesser degree, negatively related to precipitation. Males and females showed different spatial distribution patterns. Males were more numerous in the lower canopy of the forest, whereas females were more abundant in the higher canopy. Males also were found more often in deciduous vegetation than on conifers, the inverse being observed for females. We conclude that sylvicultural practices that might enhance habitat diversity and natural lighting should favor the activity ofW. fumiferanaeas a parasitoid of the spruce budworm,Choristoneura fumiferanaClemens (Lepidoptera: Tortricidae).

ISSN:1754-5692    

DOI:10.1093/ee/19.2.293

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The effects of several plant characters on the oviposition behavior of Hessian flies were investigated by presenting mated females with various combinations of chemical, color, and tactile cues in choice bioassays. When applied to filter paper, one plant equivalent (PE) of a chloroform extract of wheat leaves stimulated 438 times more egglaying than chloroform controls. One PE of oats extract stimulated 10 times more egglaying than chloroform controls. Wheat extracts stimulated 12 times more egglaying than oats extracts. Doseresponse tests using wheat extracts showed that females were stimulated to oviposit at concentrations as low as 0.01 PE; they laid more eggs as dosage increased. Higher dosages of oats extract (1.0 PE) were required to elicit significantly more oviposition than occurred on chloroform controls. In separate tests with and without wheat extract, females laid more eggs on yellow, green, and orange papers than on blue and red papers. Choice tests using green and grey filter paper strips indicated that egglaying responses were stimulated primarily by hue rather than intensity of colors. Tactile cues associated with venation of grass leaves were mimicked by making parallel grooves (“veins”) down the long axis of wax-covered filter paper. In tests without wheat extract, females laid 28 times more eggs on the veined surface than on the smooth surface. With wheat extract present, the veined surface elicited only two times more egglaying than the smooth surface. Vertical grooves received four times more eggs than horizontal grooves. In a test using a factorial treatment design with chemical, color, and tactile cues either absent or present, females laid the most eggs on the treatment that combined all three cues. Removal of chemical cues caused a significantly larger reduction in egglaying (93%) than did the removal of either tactile or color cues (70%)

ISSN:1754-5692    

DOI:10.1093/ee/19.2.303

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Numerous species of epigeal arthropods collected from apple orchards in southern Ontario were predaceous on larvae and pupae of the apple maggot,Rhagoletis pomonella(Walsh). However, few species fed extensively on dipterous prey and the numbers of individuals that were serologically positive with antiserum toR. pomonellawere generally low. The ground beetlesAmara aeneaDeGeer,Harpalus aeneusF., andPterostichus melanariusIlliger; the staphylinids,Philonthusspp.; the ants,Formica fuscaL. andMyrmicasp.; and the spider,Trochosa terricolaThorell, appeared to be the most frequent predators ofR. pomonella.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.309

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Abundance and population growth rates of the sweetpotato weevil,Cylas formicarius elegantulus(Summers), were compared on different cultivars of sweet potato,Ipomoea batatas(L.) Lam. (cvs. Campeon, Centennial, Picadito, and Regal) in southern Florida. The within-vine and within-root distributions of the weevil on plants also were determined. Studies were conducted during the cool, dry, winter and the warm, wet, summer growing seasons. Weevils were more abundant and populations increased more rapidly during the summer than during the winter season. During the summer season, they tended to be most abundant on ‘Centennial’ followed in decreasing order by ‘Regal’ and ‘Picadito.’ Weevils were more abundant and populations increased more rapidly in roots than in vines of ‘Centennial,’ ‘Regal,’ and ‘Campeon,’ whereas they were more abundant or as abundant, and populations increased more rapidly, in vines than in roots of ‘Picadito.’ In vines, weevil populations increased more rapidly on ‘Picadito’ and on one planting of ‘Centennial.’ In roots, populations increased most rapidly on ‘Centennial’ and on one planting of ‘Regal.’ Overall, populations increased most rapidly on ‘Centennial’ and least rapidly on ‘Campeon.’ The weevil displayed a characteristic within-plant distribution that differed among cultivars, Overall, 81.6, 90.2, 91.2, and 91.3% of the total weevil populations within the vines and roots of ‘Picadito,’ ‘Centennial,’ ‘Regal,’ and ‘Campeon,’ respectively, were found below the soil surface. Also, 87.4, 78.7, 89.3, and 78.0% of the total weevil population in vines and roots were found in the region of the plant extending from 15 cm below the crown to 10 cm above the crown on ‘Campeon,’ ‘Centennial,’ ‘Regal,’ and ‘Picadito,’ respectively. These data will help to develop a sampling plan for sweetpotato weevil on cultivated sweet potato.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.313

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Populations ofNasonia vitripennisWalker (Hymenoptera: Pteromalidae) were collected from house flies(Musca domesticaL.) at poultry facilities in Sullivan County, New York (NY), and Zimbabwe, Africa (Af). In laboratory studies, the two populations parasitized approximately the same number of hosts, but more NY strain progeny emerged per host pupa than did Af strain progeny. Oviposition rates were similar between the two strains, but a larger number of Af individuals died during development within the host pupae. A greater number of diapause larvae was produced by the NY strain. The results of this study emphasize the importance of understanding intraspecific differences in insects used as biological control agents.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.322

出版商:Oxford University Press    

年代:1990

数据来源: OUP