摘要:

In 1991, late instars of gypsy moth,Lymantria dispar(L.), were sampled and diagnosed for infections of the pathogenic fungusEntomophaga maimaigaHumber, Shimazu&Soper and for gypsy moth nuclear polyhedrosis virus (NPV) at 50 sites in Michigan. Approximately 1,500 larvae were collected and reared from these sites, and no infections ofE. maimaigawere detected. From 1991 to 1993, we tested the efficacy of 2 inoculative–release methods forE. maimaigain replicated plots at 3 research sites by relocating soil containingE. maimaigaresting spores from Massachusetts to Michigan or by releasing inoculated larvae onto boles of trees. In the 2nd yr after introduction,E. maimaigabecame established (9–40% infection) where both inoculation methods were used, and a low level of infection was detected in control plots (0.5–2.4%). In the 3rd yr, epizootics ofE. maimaigaoccurred at all 3 research sites, with the incidence of infection ranging from 20 to 99% in both treated and control plots. Infection levels were correlated with precipitation and relative humidity ≥90% for 2 wk preceding larval sampling. In 1993, egg mass densities at the 3E. maimaigastudy sites averaged 3– to lO–fold lower than in adjacent oak forest. We found that it is easy to introduceE. maimaigato new locations even in the midst of an epizootic of gypsy moth NPV and thatE. maimaigareduces gypsy moth populations to levels lower than that caused by NPV alone.

DOI:10.1093/ee/24.6.1685

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Purple locoweed,Astragalus mollissimusTorrey, a native rangeland weed, is considered one of the most destructive weeds in the western United States. The chemical swainsonine, a secondary plant compound found inA. mollissimus, causes physiological and morphological abnormalities in domestic cattle, sheep, and horses. In 1991,Cleonidius trivittatus(Say), a weevil native to North America, was found attacking a large population of locoweed in northern New Mexico. Four study plots were established at Amistad, NM, in 1992 and 3 plots were established at Gladstone, NM, in 1993. Twenty–five1.0–m2quadrats were sampled every 2 wk from 28 March to 26 September 1992 and every 3 wk from 15 April to 4 September 1993 to determine the bionomics ofC. trivittatusand its interaction with locoweed.C. trivittatuswas determined to have 4 instars. Stadium length was 10, 13, 27, 47, and 16 d for 1st, 2nd, 3rd, and 4th instar, and pupal stages, respectively, in 1992 and 19, 14, 22, 50, and 18 d for 1st, 2nd, 3rd, and 4th instar, and pupal stages, respectively, in 1993.C. trivittatuslays more eggs as plant size increases. Substantial locoweed mortality results from feeding by more than 2 weevil larvae per plant.

DOI:10.1093/ee/24.6.1696

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

The natural control exerted byTrissolcus basalis(Wollaston), a solitary egg parasitoid ofNezara viridula(L.), in soybean fields in central Italy over 6 yr has been assessed.T. basaliswas the only egg parasitoid attackingN. viridulaegg masses. In total, 260N. viridulaegg masses were collected. Of these, 105 contained at least 1 egg parasitized byT. basalis. Approximately 20% of egg masses were parasitized during the first 2 yr (1986 and 1987), increasing to 50% in the following years (1988, 1990, 1991, and 1992). Parasitism efficiency (the percentage of eggs parasitized over the total egg masses discovered) was =65% in 1986 and 1987, significantly less than in 1988 and 1990 (=92%). The impact of the parasitoid on theN. viridulapopulation was low,<13%, for the first 2 yr, and much higher, =40%, in the following years.

DOI:10.1093/ee/24.6.1703

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Four combinations of healthy (H) and infected with nonoccludedMicroplitis croceipesbaculovirus (I) adultMicroplitis croceipes(Cresson) were paired and mated as follows: group I, I♂ + I,♀; group II,H♂+ I♀ ; and group III, 1♂ + H♀; and group IV (control), H♂ + H♀. Females were allowed to parasitize 3rd instars of tobacco budworms,Heliothis virescens(F.). Percentage parasitization by group IV females was significantly higher than that of any other group. Parasitization by groups I, II, and III was lower than that by group IV by 25.7, 13.8, and 10.4%, respectively. The number of offspring from group IV was also significantly higher than that from the other groups. Groups I, II, and III averaged 95.4, 79.8, and 47.6% fewer offspring, respectively, than group IV Developmental times from oviposition to larval emergence, larva to cocoon, and c ocoon to adult were longer in groups I, II, and III than in group IV Percentage mortality from all immature stages up to adult was significantly higher in groups I, II, and III than in group IV. Adult longevity in both sexes in groups I, II, and III was shorter than in group IV. Most of the adults that originated from healthy parents lived>I wk, whereas those from infected parents lived<1 wk.

DOI:10.1093/ee/24.6.1708

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Approximately 100Calosoma sycophantaL. adults were released in each of 5 plots located near the leading edge of gypsy moth,Lymantria dispar(L.), expansion in Delaware, Michigan, and West Virginia. Before release, naturally occurring beetle populations were present in West Virginia, but not in the other states. Gypsy moth pupal numbers and numbers of pupae eaten by larvalC. sycophantawere counted under burlap bands in both release and paired control plots to assess the effectiveness of the beetle. There was a significant positive partial correlation between pupal survival and abundance of beetle larvae; gypsy moth pupal survival was high when predator population densities were high. This is not what would be expected ifC. sycophantawere controlling the pest, but the data show that the beetle was capable of reproducing in release areas. These results indicate that it may be useful to release the beetle into other parts of the leading edge of gypsy moth infestation and in other areas where the beetle is not abundant.

DOI:10.1093/ee/24.6.1713

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Four methods were used to estimate mortality of the boll weevil,Anthonomus grandisBoheman, fromCatolaccus grandis(Burks) parasitism in 2 locations in the Lower Rio Grande Valley, TX, during 1992 and 1993 after inundative releases of this parasitoid. Percentage of parasitism was calculated from densities of parasitized and healthy hosts (3rd instars and pupae). The graphical method of Southwood and Jepson was used. Densities of emergence holes from cotton,Gossypium hirsutumL., floral buds (squares) and bolls by the parasitoid or host were determined. Life table analysis on boll weevil cohorts placed in the field was also used. Estimates of percentage of mortality fromC. grandisparasitism ranged from 65 to 95% in 1992 and from 22 to 87% in 1993. Life table analysis and population density data showed evidence of suppression of boll weevil populations during 1992 and 1993 in all fields. Boll weevil survival (from egg to adult) in the control cotton fields ranged from 72.8 to 78.2%. In contrast, boll weevil survival was only 0.5–11.8% in the cotton fields treated with augmentative releases ofC. grandis.

DOI:10.1093/ee/24.6.1718

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

The effects of wildflowers on the longevity and fecundity ofDiadegma insulare(Cresson), one of the major parasitoids of diamond back moth,Plutella xylostella(L.), in North America, were studied in the field. Wildflowers provided nectar sources forD. insulare. Longevity and fecundity of the parasitoid female varied with wildflower species and the morphological characteristics of the flower. Several flowers. including Brassica kaber (D.C.) Wheeler,Barbarea vulgarisR. Br., andDaucus carotaL., supplied nectar and resulted inD. insularelongevity and fecundity equal to when honey–water was supplied as food. Others, includingErysimum cheiranthoides L.andThlaspi arvense L., were not significantly better than no food at all.Chenopodium albumL. andSonchus arvensisL. did not provide available nectar, however, adult parasitoids fed on honeydew excreted by Aphis fabae (Scopli)feeding on the plants. Fecundity ofD. insularegenerally peaked 6–15 d after adult emergence. An increase in longevity and fecundity was correlated with flower corolla opening diameter. Shading also increased longevity and fecundity ofD. insulare. The oviposition behavior within 1 min of exposure to diamond back moth larvae was highly correlated with longevity and fecundity ofD. insulare, whichwe considered indices of food quality. Seasonal manipulation of the diversity and distribution of wildflowers in the cabbage field and adjacent habitats, as well as providing shade forD. insulare, could increaseD. insulareeffectiveness in management of diamondback moth.

DOI:10.1093/ee/24.6.1726

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Aphids attacking citrus can be serious pests when they transmit severe strains of citrus tristeza virus. As part of an environmental assessment of exotic parasitoids of aphids, we compared the thermal relationships ofAphelinus spiraecolaeEvans&Schauff andAphelinus gossypiiTimberlake with the indigenous parasitoid,Lysiphlebus testaceipes(Cresson), on the black citrus aphid,Toxoptera aurantii(Boyer de Fonscolombe), in growth chambers in Florida. Overall, L. testaceipes development time was shorter than that of the aphelinids ranging from 18.7 to 42.5% less throughout the range of temperatures tested (15–30°C). Development times between the aphelinids were similar except at 15°C whereA. spiraecolaerequired 3.5 d more thanA. gossypii. Developmental thresholds and degree–day requirements forL. testaceipeswere 7.5° and 212.8 DD; forA. spiraecolaewere 7.9°C and 294.1 DD; and forA. gossypiiwere 6.7°C and 312.5 DD, respectively. Pupal mortality ofL. testaceipesincreased greatly at 27°C and above, ranging from 24.8 to 44%; whereas mortality of tile aphelinids remained low, ranging from 9.1 to 10.2% forA. spiraecolae, and 13.3 to 15.8% forA. gossypii. Based on these relationships, we anticipate that these parasitoids can coexist and that different thermal tolerances should broaden their potential as natural enemies of aphids attacking citrus.

DOI:10.1093/ee/24.6.1736

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

The lethality of CryIA(a) and CryIA(c)insecticidal crystal proteins fromBacillus thuringiensisto gypsy moth,Lymantria dispar(L.), was significantly enhanced by the presence of either bacterial spores or vegetative cells ofEscherichia coliand several forest epiphytic bacteria. Spores fromB. cereus, B. megaterium, andB. subtiliswere as effective synergizers of the CryIA insecticidal crystal proteins as spores from an acrystalliferous strain ofB. thuringiensis(HD-73 cry−).Klebsiellasp.,K pneumonia, Erwinia amylovara, E. rubrifaciens, Pseudomonas fluorescens, Xanthomonassp.,X. campestris, Actinomycessp.Corynebacteriumsp.,Flavobacteriumsp., andEscherichia coliwere effective synergizers of at least one of the CryIA toxins. OnlyP. syringaewas not synergenic. In the absence of the CryIA toxins, none of tile bacterial cell or spore synergists exhibited toxicity or inhibited larval growth or molt to the next instar.

DOI:10.1093/ee/24.6.1741

出版商:Oxford University Press    

年代:1995

数据来源: OUP

DOI:10.1093/ee/24.6.1748

出版商:Oxford University Press    

年代:1995

数据来源: OUP