2012 Annual Report
1a.Objectives (from AD-416):
Develop the potential of entomopathogenic fungi to manage pear thrips, western flower thrips and other major insect pests with soil-dwelling stages, and to encourage the implementation of fungus-based biocontrol methods as part of total IPM approaches for use greenhouse and forest environments against these pests.
1b.Approach (from AD-416):
Utilize entomopathogenic fungi from the University of Vermont (UVM) collection, the ARS Collection of Entomopathogenic Fungal Cultures (ARSEF; Ithaca, NY), and newly isolated strains from greenhouse and field studies to develop improved methods for the use of these fungi in practical programs for the integrated pesticidal and biological control of soil-dwelling stages of western flower thrips and other major insect pests in greenhouses as well as of pear thrips affecting sugar maple trees. The isolation and preservation of new fungal germplasm and co-deposition of old and new UVM isolates in ARSEF remain a major activity. Development of new or improved means and formulations to deliver fungal entomopathogens to control soil-dwelling stages of thrips and other insects in greenhouses is a major concern. Improving the ability of fungal control agents to resist drought and high temperatures with a balanced set of modified formulations and applications approaches is critically important.
Pear thrips populations increased to moderate to high levels in Vermont in 2012. During the summer of 2011, light damage (5 – 10% defoliation) was observed on sugar maple trees in some counties. The overwintering pear thrips populations in the soil were significantly higher in the Fall of 2011 (up to 10 adult thrips per soil sample and a mean of 4 per soil sample) than in the Fall of 2010 (mean of less than 1 per soil sample). Early spring 2012 climatic conditions were ideal for development of leaf damage to sugar maples with a week of early March temperatures between 21-27° C followed by four weeks of normally cool conditions. Sugar maple buds broke in early March and then remained static for several weeks which allowed the early–emerging pear thrips time to feed within the slowly-opening buds resulting in moderate to heavy defoliation of sugar maple across much of Vermont in June 2012 (up to 80% defoliation with a mean of about 20%). A killing frost in mid May in many places combined with the pear thrips damage caused noticeable defoliation to sugar maple trees in all but the most northern counties of Vermont. Some light pear thrips damage was observed on refoliating trees in June 2012.
A total of 128 fungal isolates were transferred to the ARS Collection, The fungal cultures were isolated from material collected in TX, AZ, NM, CT, NH, ME, and VT. They were identified as: Beauveria bassiana – 11; Metarhizium spp. – 8, Lecanicillium spp. – 30, Mariannaea spp. – 5, Isaria spp. – 22, Paecilomyces lilacinus – 3, Myriangium spp. – 7, Hirsutella spp. – 2, Pandora sp. – 1, Conidiobolus sp. – 1, Diaporthe spp. – 8, Fusarium sp. – 1, Mucor sp. – 1, Scedosporium spp. – 3, Chrysosporium sp. – 1, Gliocladium sp. – 1, Xylohypha sp. – 1, Moniliophora sp.– 1, Trichoderma sp. – 2; Bipolaris sp. – 2, Pestalotia sp. – 1. Sixteen isolates could not be identified to species. They came from the following sources: Soil from ant nests – 24 cultures; Coleoptera (Tenebrionidae, Elateridae, Carabidae, Staphylinidae, Ipidae) – 13; Diptera (Tipulidae, Simuliidae, Bibionidae, Muscidae) – 14; Hymenoptera (Formicidae, Eulopidae, Vespidae , Trichogrammatidae) – 13; Aphid – 1; Lepidoptera – 3; Pentatomidae – 1; Elongate hemlock scale, Fiorinia externa – 9; Hemlock woolly adelgid – 18; Thrips – 27; Protura – 3; Spider – 1; Mites – 1.
Six geographically distant Beauveria bassiana isolates: ERL-1170 = CA-603 (ARS-7060), ERL-1578=DV-05/1, ERL-1576=Thr-08-B2, ERL-167=SPTR-022 (ARS-5672), ERL-923=0511B (ARS-4866) and the commercial strain GHA were used to create productive and thermoresistant heterokaryons with high insecticidal activity. These isolates were selected based on their thermotolerance, virulence and mass production potential. ARS-7060 had high insecticidal activity, grew rapidly and produced numerous conidia; ERL-1578 was highly resistant to extreme temperature; ERL-167 demonstrated good efficacy to Sunn Pest under field conditions in West Asia; ERL-23 and ERL-923 were obtained from places with hot summer temperatures. GHA was used as the industrial standard. Each was characterized for its production properties. Hyphal fusants were obtained by jointly cultivating fungi on agar blocks, and 37 paired isolates from border zones were identified as potential heterokaryons. After three cycles of incubation, the cultures were exposed to 45°C and streaked on ¼ SDAY and PDA medium to select thermotolerant colonies. Four survived after exposition for 90 minutes on PDA and three – on ¼ SDAY medium. The most thermotolerant was an isolate obtained from a combination of ERL-1170 and ERL-167. All paired isolates were mass produced, their rate of growth and productivity studied and their efficacy vs. Frankliniella occidentalis determined. All were more efficacious than GHA. (3,061)