摘要:

Environmental factors hypothesized to affect production of the Korean strain of the parasitoid,Cotesia melanoscelaRatzeburg, from larvae of the gypsy moth,Lymantria disparL., were examined to determine the optimum conditions for mass rearing. Maximum parasitoid production occurred with an exposure time of 24 h, a parasitoid : host (P:H) density of 5:50, an oviposition temperature of 28°C, use of first- and second-instar hosts, use of 8-d-old ovipositing females, and with exposure of ovipositing females to a light intensity of 1,452 lux. Neither the presence of males within oviposition cups nor time of day (a.m. or p.m.) significantly influenced the number of progeny produced or their sex ratio (P= 0.05). Among those external factors examined, only age of female parasitoid significantly altered the sex ratio of progeny.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.127

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Predation onLiothrips urichi, introduced to Hawaii to control the weedClidemia hirta(L.) D. Don, was studied in field-cage exclusion experiments. Thrips in open cages (exposed to predation) experienced>40% mortality compared to<10% mortality in closed cages. Eggs and first instar larvae had the highest mean mortality. Two predators,Pheidole megacephala(Fabricius) (Formicidae) andMontandoniola moraguesi(Puton) (Anthocoridae), were observed attackingL. urichiin the cages. Their combined effect was approximately twice that observed in cages that selectively excludedP. megacephala, which suggested that their individual effects on the thrips were similar. Predation onL. urichimay reduce its effectiveness as a biological control agent againstClidemia hirta(Melastomataceae) in Hawaii.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.132

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

Vertical movement of commercially formulated conidia ofBeauveria bassiana(Balsamo) Vuillimen was measured by recovery of colony-forming units (CFUs) at selected depths in four soil series after application of an aqueous suspension of conidia to soil surfaces. In greenhouse studies with soil blocks (40 by 20 by 20 cm) removed from field plots with a coring device, the number of CFUs recovered 72 h after application from depths below the surfaces was correlated (P= 0.0001) with water infiltration values of the respective soils. However, 95% of the total number of CFUs recovered in core samples of the Townley (29% sand, 32% clay, 39% silt), Greenville (64% sand, 28% clay, 8% silt), and Cecil series (59% sand, 22% clay, 19% silt) soils remained at the surfaces. In the Tifton series soil (87% sand, 5% clay, 8% silt), 87% of the total CFUs were recovered from the surface with an additional 9% recovered 4 cm below the surface. Core samples taken 2 h after application of an aqueous suspension of conidia to field plots also indicated that the four soils restricted vertical movement of the conidia. Greater than 94% of the total number of CFUs recovered in the cores were from the upper 5 cm of the profile of each soil series. At the 5–10 cm depth, 0.7, 1.8, 3.3, and 4.4% of the total CFUs were recovered from the Cecil, Greenville, Tifton, and Townley series soils, respectively. Only small percentages of total CFUs were recovered from the 10–15 cm profile of each soil. Retention of conidia in the upper profile of these soils appears to be caused by mechanical filtration within the soil structure.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.135

出版商:Oxford University Press    

年代:1988

数据来源: OUP

摘要:

In a 3-yr study, field plots of Katahdin potatoes in Tully, N.Y., were treated withBeauveria bassiana(Balsamo) Vuillemin at rates of 5 × 1012and 5 × 1013colony-forming units/ha for control of Colorado potato beetle (Leptinotarsa decemlineata(Say)).B. bassianatreatments were compared with a control of water plus surfactant and with insecticide treatments of oxamyl (184 g active ingredient [AI]/ha) in 1983, or fen valerate (18.4 g [AI]/ha) plus piperonyl butoxide (PBO) (73.6 g [AI]/ha) in 1984 and 1985. In 1983,B. bassianaand control treatments were not significantly different regarding larval populations or tuber yield, but few adults emerged fromB. bassiana-treated plots. Field-collected third- and fourth-instar larvae developedB. bassianamycoses (98% of the test population for the high rate ofB. bassianaand 64% for the low rate) when held at high humidity conditions (RH>90%) for 11 d. Because theB. bassianaformulation rapidly lost>90% of the spore viability before applications were initiated, no significant results were observed in 1984. The 1985B. bassianaformulation maintained spore viability well and produced significant reductions in third- and fourth-instar larval populations (65.8% for high and 39.5% for lowB. bassianatreatments). For high and low treatments in 1985, respectively, 28.3% and 20.0% of field-collected third- and fourth-instar larvae that were held at high humidity conditions developedB. bassianamycoses. Adult emergence studies using field cages indicated no reduction in 1985 adult populations for the lowB. bassianatreatment, but a 71.6% reduction in the highB. bassianaplots. Total 1985 marketable tuber yields for fenvalerate + PBO, highB. bassiana, lowB. bassiana, and control treatments were, respectively, 28.2, 13.6, 8.2, 3.2 t/ha, and were significantly different for all treatments.

ISSN:1754-5692    

DOI:10.1093/ee/17.1.140

出版商:Oxford University Press    

年代:1988

数据来源: OUP