Gypsy Moth - a native of EURASIA

Transcription

1 BI/ENT300, HORT330 PESTS, PLAGUES AND POLITICS LECTURE 22 INVASION OF THE KILLER MOTHS (GYPSY) ====================================================== Gypsy Moth - a native of EURASIA Taxonomy: Order - Lepidoptera Genus - Lymantria {Porthetria} species - dispar (L.) Holometabolous - pest stage is the larva Larvae herbivorous!!!!! U.S. History: Imported into Medford, MA by Leopold Trouvelot ca [Louie was studying diseases of silkworms & wanted to do some hybridizing - Louie was a French astronomer working at Harvard] Some moths escaped his home laboratory into the surrounding forests (27 Myrtle Street, Medford) first serious defoliations took place (20 years after escape) Mass. Legislature comes up with $25,000 for an eradication program (the first of many such legalized appropriations) Slow expansion from New England ever since Current Range: Epidemic In: CN, MA, NH, RI, VT, DE, ME, MD, NY, NJ, PA Parts of: MI, NC, OHIO, VA, WV Localized in: AL, AK, CA, CO, ID, IL, IN, MINN, NE, TN, UT

2 2 ECOLOGY WI, WA,& beloved ORGON. i.e., some 29 states. Defoliation Statistics: million acres million acres million acres million acres [pest always most damaging on the leading edges of an outbreak] Realized, only too recently, that infestation(s) too widespread for any hope for eradication - emphasis now on: 1) Population Suppression 2) Regional Management =================================================== Plant Hosts: Larvae can eat foliage of >300 known species of trees and shrubs. Hardwood preferred, especially OAK species. Damage - complete defoliation under 'outbreak' conditions (an early Spring defoliator) LIFE HISTORY Univoltine - mortality of preferred tree species can approach 50% especially after several years of consecutive defoliation. - trees weakened and susceptible to attack from disease - conifers usually die after one complete defoliation. - Also Human Nuisance Factor!!!! Adults: Males look different from females (hence the name dispar)

3 3 SPREAD Females don't Fly!!!! (actually, very weak fliers) Adults emerge in midsummer - males 1 to 2 days before females Mating: females release a sex attractant pheromone. males will/can multiple mate - females apparently not. Females need to mate within three days of emerging from pupa - if not they enter what's known as the "old maid" syndrome, i.e., run out of pheromone and stand little chance of attracting a male. Adults life ca. one week!!!! - and do not feed. Females begin egg laying soon after mating!! EGG: 8 to 10 months in egg stage - a DIAPAUSE stage and the strategy for over-wintering. Females lay egg BATCHES covering them with abdominal scales A single egg Batch will average ca. 750 eggs. Batches laid on trucks of trees, often in places that are dark and provide some shelter from predators, parasites and weather. LARVA: After hatching from egg it is: positively phototactic negatively geotactic - ergo it goes UP Dispersal: via ballooning with casting of silk thread On host plant: EAT & EAT some more!!! One larvae consumes ca. 12 meter of foliage during its 5-6 larval instars Ca. 6 to 8 weeks to pupation. PUPA: A short stage of ca. two weeks in some protected site. ================================================== Natural Movement: Slow via ballooning

4 4 Anthropogenic: eggs masses on vehicles (RVs a big problem) CONTROL: Non-Chemical Biological 1) Destruction of egg masses 2) Quarantines Natural Enemies: USDA program began in 1905 Successes: ten species of parasites (flies & wasps) one species of predaceous beetle Searches in Europe and more recently in Asia Pathogens: B.t. - widely used - requires multiple applications each season - the "material" of choice for the last decade Streptococcus faecalis - another bacterial species Nucleopolyhedrosis virus (NPV) Causes "Wilt Disease" An accidental introduction Commercial known as "GYPCHEK" Genetic Control Sterile Male technique not considered feasible because of the huge numbers of males that would be required. (a 100 : 1 ratio necessary) Potential use of intraspecific racial crosses that result in sterile offspring - e.g., use of Japanese male gypsy moths. Trapping Use of female sex attractant pheromones "DISPARLURE" Control (male disruption hypothesis) & Survey

5 5 Chemical Control You name it and it has probably been tried. Pre-WWII with arsenicals DDT early on SEVIN from early 1970 ties to mid-1980 ties Big Problem for non-target species; e.g. honey bees et alia THE OREGON GYPSY MOTH STORY First detected in Multnomah County in summer of 1979 Oregon Department of Agriculture (ODA), along with ODF&W, BLM, FS began a pheromone trapping detection/survey program Trapping (for survey & control) Detection - one trap per mi 2 (sometimes 2 to 4) Delimiting - (once the moths are found) - 16 to 49 traps per mi 2 Mass trapping for possible control 1,900 to 5,800 traps per mi 2 (3 to 9 per acre) 1981 Salem infestation severe enough for pesticide intervention in ,000 acres sprayed ca. Salem aerially sprayed twice with SEVIN 1983 Localized ground spraying within Willamette Valley 1984 Aerially B.t. vin. Corvallis (960 acres) Big Program in Lane County - 1,200 mi 2

6 6 At that time it was the biggest infestation in the western U.S.!!! Lots of problems for Christmas tree industry - CA threatened quarantine Lots of problems with 2% lunatic fringe that said NO Spray!! ,000 acres with B.t ,000 acres ,420 acres ,915 acres Zero acres and no moths detected. [ sterile egg masses released in Multnomah Co. - discontinued as it was realized that too few sterile males were produced]. The Oregon Department of Agriculture Approach/Philosophy to Gypsy Moth 1) Quarantines to limit movement 2) Public Education 3) Statewide detection via pheromone trapping 4) Application of "pesticides" to known infestations 5) Mass trapping 6) Identification of human migrants from known gypsy moth area New Problem The Dissolution of the U.S.S.R opened western Russian (Siberian) ports for international trade in and more importantly trade OUT!!!! Native Gypsy Moth of Siberia in an outbreak phase at this time. While the same species; a different BIOTYPE-RACE-SUBSPECIES Problems: 1) females could and do fly well (20 to 30 miles) 2) different host plant preferences (conifers on the preferred menu) 3) difficult to impossible to differentiate between the two biotypes (strains) in the field.

7 7 July & August Asian Gypsy Moths detected in: British Columbia - Washington - Oregon (single specimen near Portland docks) HOW??? - From Russian ships of commerce. Potential for a disaster to our forest products industry quickly realized!!! Estimated that for Washington alone it could result in lost revenues >46 million per annum. (figures lost timber, suppression costs, management costs, ad infinitum) If established, WDA authorities estimate 80,000 to 200,000 acres would require treatment. Massive B.t. spray campaign mounted in Spring/Summer of With help from federal government via APHIS (Animal & Plant Health Inspection Service - a branch of U.S. Department of Agriculture. A multimillion $$$$ campaign For Oregon latest report from 1992 late Summer monitoring is successful 'eradication.' Suggested Readings Johnson, K.J.R., Mudge, A.D. and L.C. Youngs The gypsy moth in Oregon. Oregon Dept. of Agriculture. 17 pp. Myers, J.H. (1993) Population outbreaks in forest lepidoptera. American Scientist 81(3):