Host effects on the development and fecundity of gypsy moth, Lymantria dispar L., reared under field conditions

1991 ◽  
Vol 69 (8) ◽  
pp. 2217-2224 ◽  
Author(s):  
Diana J. Hamilton ◽  
Martin J. Lechowicz
Keyword(s):  
Gypsy Moth ◽  
Acer Saccharum ◽  
Sugar Maple ◽  
Field Conditions ◽  
Pupal Weight ◽  
Egg Mass ◽  
Red Oak ◽  
Moth Population ◽  
Interspecific Differences ◽  
Rate Of Increase

We reared gypsy moth larvae outdoors under natural temperature and photoperiod regimes on red oak (Quercus rubra L.) and sugar maple (Acer saccharum Marsh). Initiation of the experiment coincident with the peak hatch of the local gypsy moth population assured normal synchrony between foliage quality and larval development. Compared with larvae reared on oak foliage, the mortality of maple-fed larvae is greatest and development slowest in the first instar. Overall, the larvae reared on sugar maple have higher mortality, extended development time, lower pupal weights, and lower fecundity relative to larvae reared on red oak. The mean diameter of individual eggs did not differ between oak- and maple-fed larvae, nor was the rate of increase in egg mass weight with female pupal weight host dependent. The egg masses from oak-fed moths hatched more completely than did those from moths reared on maple. In the interaction between these two abundant potential hosts and gypsy moths, the interspecific differences between the hosts are more important than any effects of seasonal asynchrony between larvae and foliar development. Gypsy moth larval success is much greater on red oak, and survival and reproduction on sugar maple under field conditions are likely to be marginal at best.

scholarly journals Effectiveness of Diflubenzuron and Bacillus thuringiensis Against Gypsy Moth Populations

1997 ◽  
Vol 14 (3) ◽  
pp. 135-140 ◽  
Author(s):  
Kevin W. Thorpe ◽  
Richard L. Ridgway ◽  
Ralph E. Webb
Keyword(s):  
Bacillus Thuringiensis ◽  
Population Density ◽  
Gypsy Moth ◽  
Mass Density ◽  
Larval Mortality ◽  
Larval Density ◽  
Egg Mass ◽  
Percent Reduction ◽  
Moth Population ◽  
Oak Trees

Abstract Aerial applications of Bacillus thuringiensis Berliner subsp. kurstaki (74.1 billion international units/ha per application; single and double applications), diflubenzuron [69 g (ai)/ha], and no treatment were evaluated. Treatment effects were estimated from frass collections, defoliation, counts of pupae under burlap, and egg-mass counts. Estimates of larval density in the canopy 20 days after treatment ranged from 318.3 to 55.5 larvae per m² in the control- and diflubenzuron-treated plots, respectively. Larval density was reduced in all treatments, and was lowest in the plots treated with diflubenzuron and two applications of B. thuringiensis. Population density rapidly declined in the control plots, and by June 20, when larvae were predominantly in the fifth and sixth instars, no significant differences in larval density were detected among the treatments. Significantly less defoliation occurred to oak trees in the treated plots, but no differences were detected among the spray treatments. Counts of pupae under burlap, postseason egg-mass counts, and percent reduction in egg-mass density did not differ significantly among treatments or versus controls. These results suggest that diflubenzuron and double B. thuringiensis treatments caused higher levels of larval mortality than occurred with a single B. thuringiensis application, but that with a naturally declining gypsy moth population the final levels of damage were the same under all treatments. North. J. Appl. 14(3):135-140.

Augmenting Nucleopolyhedrovirus Load in Gypsy Moth (Lepidoptera: Lymantriidae) Populations with Egg Mass Treatments

2003 ◽  
Vol 38 (2) ◽  
pp. 300-313 ◽  
Author(s):  
R. E. Webb ◽  
G. B. White ◽  
K. W. Thorpe
Keyword(s):  
Gypsy Moth ◽  
Early Treatment ◽  
Adult Emergence ◽  
Field Studies ◽  
Host Population ◽  
Egg Mass ◽  
Moth Population ◽  
Egg Masses ◽  
Entomophaga Maimaiga ◽  
Virus Dose

Previous observations show that gypsy moth, Lymantria dispar L., mortality induced by the fungus Entomophaga maimaiga Humber, Shimazu & Soper is quickly manifested as host population density increases. However, the gypsy moth nucleopolyhedrovirus (LdMNPV) lags behind the rebounding gypsy moth population. In this study, egg masses were contaminated with virus to successfully augment LdMNPV in gypsy moth populations in Virginia. Laboratory bioassays determined the approximate LdMNPV dose to apply to egg masses with and without the addition of the virus enhancer Blankophor BBH to the spray mixture. The highest dose of virus (5.3 × 105 PIBs/mL) tested without Blankophor BBH gave 82.3% mortality. Mortality for this virus dose increased to 91.8% when 1% Blankophor BBH was added. Field studies established that application of virus at an earlier date (04 April) was as efficacious as an application made at a later date (12 April); this study also included a further assessment of the addition of Blankophor BBH to the spray mixture. While application of LdMNPV + Blankophor BBH resulted in faster kill, levels of kill were similar (88.0% for early treatment and 78.8% for later treatment for virus applied alone versus 87.8% for early treatment and 89.1% for later treatment for virus + Blankophor BBH). However, a higher than expected number of cadavers in the LdMNPV + Blankophor BBH treatments had few or no polyhedral inclusion bodies (PIBs). Finally, virus infection resulting from the application of LdMNPV to pupae in June 1998 was compared with infection levels seen after the application of virus to egg masses in April 1999. The April 1999 treatment to egg masses clearly resulted in a higher kill of emerging larvae (=79.3% mortality) compared to the June 1998 treatment to female pupae (with virus incorporated into the egg masses laid by females after adult emergence) (=13.7% mortality). The virus was recovered season-long from larvae collected from populations in the treated plots (but not from control plots), indicating within season spread.

scholarly journals Biological Efficacy of Gypchek Against a Low-Density Leading-Edge Gypsy Moth Population

2004 ◽  
Vol 21 (3) ◽  
pp. 144-149 ◽  
Author(s):  
R. E. Webb ◽  
G. B. White ◽  
T. Sukontarak ◽  
J. D. Podgwaite ◽  
D. Schumacher ◽  
...  
Keyword(s):  
Gypsy Moth ◽  
Treatment Success ◽  
Leading Edge ◽  
Early Morning ◽  
Egg Mass ◽  
Moth Population ◽  
Environmentally Sensitive Areas ◽  
Gypsy Moths ◽  
Operational Application ◽  
Realistic Assessment

Abstract The USDA's Slow-the-Spread (STS) program seeks to retard the continued spread of the gypsy moth using ecologically desirable treatments such as Gypchek. At “trace” population levels, evaluation of treatment success by defoliation reduction, egg mass reduction, burlap counts, or larval collection is not feasible. We adapted the “bugs-in-bags” technique to evaluate an operational application of Gypchek against trace populations of gypsy moths in Wisconsin, an STS area. Late first- or early second-instar gypsy moth larvae were placed, 1 per bag or 10 per bag, in sleeve cages placed over treated foliage one hour posttreatment. Mortality observed for larvae placed 10 per bag was equivalent to that recorded for larvae placed 1 per bag, and both should approximate the mortality occurring to the larvae scattered in nature. A single application of Gypchek applied in 9.5 liters of Carrier 038 at 1012 polyhedral inclusion bodies per hectacre was found to induce a higher rate of infection in blocks treated in the early morning than in blocks treated later in the morning, correlating significantly with a lowering of relative humidity and an increase in temperature and wind speed. Recorded levels of efficacy (24–67%) did not meet quarantine objectives; however, Gypchek, which kills only the gypsy moth, remains a product of choice by many land managers for use in certain environmentally sensitive areas. These results provide such land managers with a realistic assessment of the level of efficacy that can be expected from this formulation of Gypchek used at the currently recommended dose. North. J. Appl. For. 21(3):144–149.

scholarly journals Effects of Pyriproxyfen on Life Table Indices ofPlutella xylostellain Multigenerations

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Mohammad Mahmoudvand ◽  
Saeid Moharramipour ◽  
Mehrdad Iranshahi
Keyword(s):  
Sublethal Effects ◽  
Diamondback Moth ◽  
Reproductive Rate ◽  
Good Choice ◽  
Pupal Weight ◽  
Moth Population ◽  
Net Reproductive Rate ◽  
Treatment Groups ◽  
Rate Of Increase ◽  
Major Pest

The diamondback moth (DBM),Plutella xylostella(L.) (Lepidoptera: Plutellidae), is a major pest of Brassicaceae family in Iran. This study investigated the sublethal effects of pyriproxyfen, a juvenile hormone analogue, on DBM, for two subsequent generations. The leaf dip bioassay method was adopted in conducting this experiment. Sublethal concentrations resulted in a significant decrease in fecundity, oviposition period, and pupal weight of parents and offspring generations. Also, the development time of DBM was prolonged after exposure to pyriproxyfen. The biological parameters such as net reproductive rate (R0) and intrinsic (rm) and finite (λ) rate of increase were lower than control in treatment groups, significantly. From our investigations, pyriproxyfen is a good choice for control of the diamondback moth population through continuous generations.

scholarly journals Biological control of gypsy moth (Lymantria dispar) by the entomopathogenic fungus Entomophaga maimaiga in Bulgaria in 2021

2021 ◽  
Vol 22 (3) ◽  
pp. 17-27
Author(s):  
Georgi Georgiev ◽  
Plamen Mirchev ◽  
Margarita Georgieva ◽  
Mihail Kechev ◽  
Sevdalin Belilov ◽  
...  
Keyword(s):  
Biological Control ◽  
Gypsy Moth ◽  
Lymantria Dispar ◽  
Entomopathogenic Fungus ◽  
Control Programme ◽  
Egg Mass ◽  
Moth Population ◽  
Entomophaga Maimaiga ◽  
Forest Enterprises ◽  
Gipsy Moth

In 2021, biological control programme against gipsy moth (Lymantria dispar) populations was carried out by introduction of the entomopathogenic fungus Entomophaga maimaiga on the territory of four State Forest Enterprises: Municipal Enterprise (ME) ‘Management of Municipal Forests, Agriculture and Forestry’, Nessebar; State Game Enterprises (SGE) Nessebar and Balchik; State Forestry (SF) Vidin. The pathogen was introduced during the period 15-26.03.2021 in 34 localities - five in ME Nessebar, eight in SGE Nessebar, ten in SGE Balchik and eleven in SF Vidin. The average number of gypsy moth population density in the locations of introduction was relatively high, ranging between 0.4-15.9 egg mass/tree in the area of ​​SGE Balchik and 11.9-65.0 egg mass/tree in the area of ​​ME Nessebar. The average mortality of young gypsy moth caterpillars (first-third instar) due to E. maimaiga varied between 2.6% (SGE Balchik) and 13.0% (SF Vidin), and of caterpillars in later fourth-sixth instar - between 20.7% (SF Vidin) and 52.4% (ME Nessebar). The overall mortality of the gipsy moth caterpillars due to E. maimaiga was lowest in the region of SGE Balchik (26.1%), followed by SF Vidin (33.7%), SGE Nessebar (48.5%) and ME Nessebar (55.9%). As a result of the introduction, gipsy moth severe outbreaks in the region of Nessebar was significantly suppressed. The high number of E. maimaiga resting spores persists in the surface layers of the soil in the other two areas (Vidin and Balchik) has the potential to suppress L. dispar attacks in next years.

Electrical properties of temperate forest trees: a review and quantitative comparison with vines

2015 ◽  
Vol 45 (3) ◽  
pp. 236-245 ◽  
Author(s):  
Evan M. Gora ◽  
Stephen P. Yanoviak
Keyword(s):  
Electrical Properties ◽  
Acer Saccharum ◽  
Sugar Maple ◽  
Acer Rubrum ◽  
Atmospheric Conditions ◽  
Growth Forms ◽  
Red Maple ◽  
Anatomy And Physiology ◽  
Empirical Survey ◽  
Interspecific Differences

Trees form the terrestrial interface with the atmosphere in forested regions. The electrical properties of trees may influence their response to atmospheric conditions and potentially lethal phenomena (e.g., lightning). We review the literature describing electrical properties of trees and provide a tabular summary of the methods and goals of each study. We hypothesized that electrical resistivity varies consistently among species and between growth forms. We surveyed resistivity of eight tree and three vine species in Michigan and Kentucky, and we quantified resistivity over a moisture gradient for wood blocks of four tree species. Resistivity varied predictably with stem diameter and differed among species and growth forms. Specifically, resistivity of trees was approximately 200% higher than resistivity of vines, and resistivity of conifers was 135% higher than that of hardwoods. The regional comparison showed no difference in resistivity of red maple (Acer rubrum L.) and sugar maple (Acer saccharum Marsh.) between Michigan and Kentucky. These results, in combination with interspecific differences observed among wood blocks, suggest that there is a phylogenetic basis for variation in resistivity that reflects differences in anatomy and physiology. Our review and empirical survey provide a framework for studying the ecological effects of lightning in the context of the electrical properties of trees.

scholarly journals Transplant Timing Affects Early Root System Regeneration of Sugar Maple and Northern Red Oak

HortScience ◽  
2002 ◽  
Vol 37 (6) ◽  
pp. 984-987 ◽  
Author(s):  
J. Roger Harris ◽  
Jody Fanelli ◽  
Paul Thrift
Keyword(s):  
Root Growth ◽  
Root System ◽  
Acer Saccharum ◽  
Sugar Maple ◽  
Red Oak ◽  
Northern Red Oak ◽  
Root Extension ◽  
Trunk Diameter ◽  
Post Transplant ◽  
Median Date

Description of early post-transplant root growth will help formulate best transplanting strategies for landscape trees. In this experiment, the dynamics of early root system regeneration of sugar maple (Acer saccharum Marsh. `Green Mountain') and northern red oak (Quercus rubra L.) were determined. Field-grown 4-year-old trees were transplanted bare-root into outdoor root observation containers (rhizotrons) in Oct. 1997, Nov. 1997, or Mar. 1998. All trees were grown in the rhizotrons until Oct. 1998 and then transplanted, with minimally disturbed rootballs, to field soil and grown for an additional two years. October-transplanted trees of both species began root regeneration earlier and regenerated more roots, as judged by accumulated root length on rhizotron windows, than Nov.- or March-transplanted trees. Median date for beginning root extension for sugar maples was 48, 22, and 0 days before budbreak for October-, November-, and Marchtransplanted trees, respectively. Median date for beginning root extension for northern red oak was 4, 21, and 14 days after budbreak for October-, November-, and Marchtransplanted trees, respectively. Height and trunk diameter growth were similar for all treatments within each species for 3 years after application of treatments. Early fall transplanting will result in earlier first season post-transplant root growth for sugar maple and northern red oak. Earlier post-transplant root growth will likely increase resistance to stress imposed by harsh landscape environments.

Gypsy Moth Management in Suburban Parks: Program Evaluation2

1994 ◽  
Vol 29 (4) ◽  
pp. 557-569 ◽  
Author(s):  
R. L. Ridgway ◽  
K. W. Thorpe ◽  
R. E. Webb ◽  
L. Venables
Keyword(s):  
Gypsy Moth ◽  
Agricultural Research ◽  
Mass Density ◽  
Larval Mortality ◽  
Management Program ◽  
Management Unit ◽  
Egg Mass ◽  
Susceptible Host ◽  
Moth Population ◽  
High Level

A specialized gypsy moth management program for urban parks was implemented in six state and county parks and the Beltsville Agricultural Research Center (BARC) in Maryland in 1990 and 1991. Decisions to treat with aerial applications of Bacillus thuringiensis Berliner (one or two applications) or diflubenzuron or to not treat were based on gypsy moth egg mass density, egg mass size, percentage of susceptible host trees, amount of previous defoliation, and the potential non-target effects of diflubenzuron. A total of 1025 and 1926 ha in the management program was treated with one and two applications of B. thuringiensis, respectively, and 1204 ha were left untreated. One block of 47 ha was treated with diflubenzuron. Larval mortality as a result of the treatments averaged 76 and 83% in areas treated with one and two applications of B. thuringiensis, respectively, and 87% in the area treated with diflubenzuron. Some noticeable defoliation occurred under all treatments. The greatest amount of defoliation (29% of total area) occurred in a management unit with an average initial egg mass density of 49,250/ha that was treated twice with B. thuringiensis. Comparisons with adjacent areas not included in the management program indicated that even when defoliation did occur, it was reduced both in severity and extent by the treatments. This evaluation of the gypsy moth management program that was developed to provide a high level of foliage protection in suburban parks indicated that a number of improvements can be made in the program. However, without more efficacious intervention tactics, the goal of preventing noticeable defoliation in any part of a management unit may not be achievable solely with biological agents where extremely high gypsy moth population densities are present.

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