Balsam Gall Midge Research Articles

Gall-maker Paradiplosis tumifex (Diptera: Cecidomyiidae) and its inquiline Dasineura balsamicola (Diptera: Cecidomyiidae): an update on epidemic episodes and seasonal ecology in Québec, Canada

AbstractThe balsam gall midge Paradiplosis tumifex Gagné (Diptera: Cecidomyiidae) is a major pest for the Christmas tree industry. This galler is frequently associated with the inquiline Dasineura balsamicola (Lintner) (Diptera: Cecidomyiidae), which is involved in the dynamics of the galler. Despite their importance, seasonal ecology of both midges under the climatic conditions prevailing in eastern Canada is still poorly understood. More importantly, nothing has yet been done to fully assess the impact of temperature on these insects, at key events such as adult emergence and larval overwintering. Here we followed P. tumifex and D. balsamicola spring phenology in the field, as well as their survival during winter diapause under simulated climatic scenarios in the laboratory. We observed spring asynchrony between fir host trees and P. tumifex in the first year of study, but under prevailing epidemic conditions, we observed no impact on summer abundance. We clarified available knowledge on their ecology, showing that overwintering habitats and strategies differ between the galler and its inquiline, which should alter pest control strategies. Experimental overwintering data suggest that diapausing conditions affect these species differentially and could potentially impact the spring sex ratio of their midges, which tends to be strongly female biased.

Diel activity patterns of Paradiplosis tumifex (Diptera: Cecidomyiidae) and its inquiline, Dasineura balsamicola (Diptera: Cecidomyiidae), within young balsam fir

AbstractField studies were carried out to assess diel activity patterns of the balsam gall midge, Paradiplosis tumifex Gagné (Diptera: Cecidomyiidae) in 2012, and its inquiline, Dasineura balsamicola (Lintner) (Diptera: Cecidomyiidae) in 2013, in a young balsam fir (Abies balsamea (Linnaeus) Miller) stand in New Brunswick, Canada. Both gallmaker and inquiline are most active during the afternoon/evening hours (17:00–22:00 hours). Male gallmaker activity was largely confined to the space below the crown and typically involved short periods of flight of <30 seconds. Calling and mating by the gallmaker occurred at ground level and were followed by dispersal of females to the vegetative crown. Female gallmakers were typically observed in the tree crown beginning in early afternoon, with peak oviposition occurring between 20:00 and 21:00 hours. Female inquilines displayed similar activity patterns, although no calling or mating were observed. Moreover, inquiline flight and foraging for oviposition sites were more active than the gallmaker, with shorter rest periods and more buds visited than the gallmaker. Our results indicate that population monitoring should focus on female gallmakers as they fly during the evening. Also, before any treatment application, care should be taken to accurately identify the insects to ensure that the inquiline is not inadvertently killed.

A Simulation Approach to Assessing Sampling Strategies for Insect Pests: An Example with the Balsam Gall Midge

Estimation of pest density is a basic requirement for integrated pest management in agriculture and forestry, and efficiency in density estimation is a common goal. Sequential sampling techniques promise efficient sampling, but their application can involve cumbersome mathematics and/or intensive warm-up sampling when pests have complex within- or between-site distributions. We provide tools for assessing the efficiency of sequential sampling and of alternative, simpler sampling plans, using computer simulation with “pre-sampling” data. We illustrate our approach using data for balsam gall midge (Paradiplosis tumifex) attack in Christmas tree farms. Paradiplosis tumifex proved recalcitrant to sequential sampling techniques. Midge distributions could not be fit by a common negative binomial distribution across sites. Local parameterization, using warm-up samples to estimate the clumping parameter k for each site, performed poorly: k estimates were unreliable even for samples of n∼100 trees. These methods were further confounded by significant within-site spatial autocorrelation. Much simpler sampling schemes, involving random or belt-transect sampling to preset sample sizes, were effective and efficient for P. tumifex. Sampling via belt transects (through the longest dimension of a stand) was the most efficient, with sample means converging on true mean density for sample sizes of n∼25–40 trees. Pre-sampling and simulation techniques provide a simple method for assessing sampling strategies for estimating insect infestation. We suspect that many pests will resemble P. tumifex in challenging the assumptions of sequential sampling methods. Our software will allow practitioners to optimize sampling strategies before they are brought to real-world applications, while potentially avoiding the need for the cumbersome calculations required for sequential sampling methods.

A sampling unit for estimating gall densities of Paradiplosis tumifex (Diptera: Cecidomyiidae) in Christmas tree stands

AbstractWe used field surveys in central New Brunswick, Canada to establish efficient sampling procedures for evaluating densities of balsam gall midge, Paradiplosis tumifex Gagné (Diptera: Cecidomyiidae), and its associated damage in balsam fir, Abies balsamea (Linnaeus) Miller, Christmas trees. Infestation was greater in larger trees than smaller trees and in mid-crown and upper-crown branches than in the lower crown. However, the relationship between gallmaker infestation and site, height class, and crown level was highly complex and may involve covariation of shoot length with height class and crown level. As a result, patterns in infestation did not lend themselves to simple interpretation. This complexity highlights the need to find sampling units that provide simpler but reasonably accurate predictors of gallmaker impact at the whole-tree scale. We identified such a sampling unit: gallmaker density in first-order current-year shoots of a mid-crown branch explained 81% of the variance in total infestation among trees.

Bottom-up trophic cascades caused by moose browsing on a natural enemy of a galling insect on balsam fir

To elucidate the impact of browsing by moose on the indigenous insect community, we investigated the abundance of a specialist insect herbivore (galler; Paradiplosis tumifex) and its natural enemy (inquiline; Dasineura balsamicola) on balsam fir saplings in the field using exclosures in Newfoundland, Canada. The number of current-year shoots on each sapling, but not the density of balsam fir saplings, was significantly higher inside exclosures, where moose had been excluded for 9–12 years, than outside exclosures. Current-year shoots were longer and contained more, but smaller, needles inside than outside exclosures. Moose browsing had a negative impact on the abundance of both the galler and its natural enemy. Gall density was 85.6% and 60.4% lower in 2006 and 2007, respectively, outside than inside exclosures. Similarly, the attack rate of D. balsamicola was 76.5% lower outside than inside exclosures in 2007. The apparent survival rate of P. tumifex larvae was similar outside and inside exclosures due to higher rates of unexplained mortality in galls outside exclosures. Survival of P. tumifex larvae was positively related to shoot length and inversely related to gall density. Only gall density was negatively related to D. balsamicola survival. Our results demonstrate that a large mammal can cause strong bottom-up trophic cascades.

Effectiveness of Penncap M in Control of Balsam Gall Midge, 1992

Abstract The experiment was conducted in a Christmas tree plantation in Jefferson, NH. The experimental design was a RCB with 12 single tree replicates. Treatments were applied 9 Jun when buds averaged 1.5 inches long and at the start of gall formation. Applications were made with a Solo backpack sprayer at a rate of 100 gal water per acre. New growth received adequate coverage. Trees were 5-7 ft tall. Air temperature at the time of treatment was 80°F. The sky was clear with no rain for 2 days. Trees were rated 15 Sep. by counting the number of twigs with live galls per 50 randomly selected twigs per tree.

THE METHOD BY WHICH LARVAE OF DASINEURA BALSAMICOLA (LINTNER) (DIPTERA: CECIDOMYIIDAE) GAIN ACCESS TO THE INTERIOR OF GALLS INDUCED BY PARADIPLOSIS TUMIFEX GAGNÉ (DIPTERA: CECIDOMYIIDAE)

The balsam gall midge, Paradiplosis tumifex Gagné, oviposits in newly opening buds of balsam fir. Eggs hatch in 2–3 days. First-instar larvae crawl to and usually settle on the proximal adaxial surface of developing needles. Needle tissues near the larva proliferate, and the larva appears to sink into the needle as the gall forms around the feeding site (West and Shorthouse 1982). Another gall midge, Dasineura balsamicola (Lintner), is an inquiline in the gall of P. turnifex. Its eggs are laid at approximately the same time and place as those of P. tumifex, and larvae of both species are often found in the same gall.

Morphology of the balsam fir needle gall induced by the midge Paradiplosis tumifex (Diptera: Cecidomyiidae)

Paradiplosis tumifex induces a simple, single-chambered, prosoplasmic gall on the adaxial surface of current-year needles of balsam fir. Proliferating and enlarged mesophyll cells surround the immature larva except for an ostiolar opening on the adaxial surface. The vascular bundle is not affected by gall formation, but the cells lining the resin ducts are altered. As the gall matures the epidermis and one or two layers of underlying mesophyll cells become lignified. Concentrations of starch granules are retained in gall cells after starch has been dissipated in tissues beyond the gall and in nongalled needles. Host damage occurs when galled needles dry and abscise prematurely.

HOST DETERMINATION OF CHALCIDOID AND PROCTOTRUPOID HYMENOPTERA ASSOCIATED WITH TWO SPECIES OF MIDGES (DIPTERA: CECIDOMYIIDAE) FOUND IN NEEDLE GALLS OF BALSAM FIR

AbstractFour species of Chalcidoidea: Tetrastichus marcovitchi (Cwfd.), Tetrastichus sp., T. whitmani (Grit.), Pseudencyrtus sp., and two species of Proctotrupoidea: Platygaster abicollis MacGown and Osgood and P. mainensis MacGown and Osgood were reared and identified as parasites of the balsam fir needle gallmaker, Paradiplosis tumifex Gagné. T. marcovitchi was the most abundant. No parasites were found on or reared from Dasineura balsamicola (Lintner). The rearing technique is given.

TWO NEW SPECIES OF CHALCIDOID WASPS (HYMENOPTERA) PARASITIC ON THE BALSAM GALL MIDGE (DIPTERA: CECIDOMYIIDAE) IN MAINE

AbstractPseudencyrtus borealis and Tetrastichus cecidivorus n. spp. are described as parasites of Paradiplosis tumifex Gagné. Both were reared from balsam fir needle galls in late summer and fall.

Biology and Taxonomy of Two Gall Midges (Diptera: Cecidomyiidae) Found in Galls on Balsam Fir Needles with Description of a New Species of Paradiplosis

The life cycle and seasonal biology is described for 2 associated cecidomyiids in needle galls of balsam fir. One species, Paradiplosis tumifex Gagne, n. sp., is responsible for the gall; the other, Dasincura balsamicola (Lintner), is an inquiline that enters the newly forming gall and eventually indirectly kills the larva of P. tumifex . Characters for the separation of the 2 species are given. The new species is described and illustrated and compared with its 4 congeners. Agevillea Hubault is a new junior synonym of Paradiplosis Felt.

TWO NEW SPECIES OF PLATYGASTRIDAE (HYMENOPTERA: PROCTOTRUPOIDEA)

AbstractSynopeas osgoodi n. sp., associated with balsam gall midge, Mariaville, Me., U.S.A., and Platygaster kimballi n. sp., associated with thistle, Houlton and Belfast, Me., U.S.A., are described herein.

TAXONOMY AND BIOLOGY OF CHALCIDOID AND PROCTOTRUPOID HYMENOPTERA ASSOCIATED WITH DASINEURA BALSAMICOLA (DIPTERA: CECIDOMYIIDAE) IN MAINE

AbstractSeventeen species of parasitic Hymenoptera were found associated with balsam gall midge in Maine. Tetrastichus marcovitchi (Cwfd.), Tetrastichus sp. near solidaginis Burks, Plalygaster mainensis MacG. and Osgd., and P. abicollis MacG. and Osgd. were the most abundant known parasites, while several other species, some of uncertain status, were less frequently encountered. A key is presented for commonly encountered species, and details of the life histories are given for important midge parasites.

TWO NEW SPECIES OF PLATYGASTER (HYMENOPTERA: PROCTOTRUPOIDEA, PLATYGASTRIDAE) PARASITIC ON BALSAM GALL MIDGE, DASINEURA BALSAMICOLA (DIPTERA: CECIDOMYIIDAE)

AbstractTwo new species of Platygaster accounting for high rates of parasitism in balsam gall midge are described. These appear to be widely distributed within the range of balsam fir in North America.

PARASITES OF THE BALSAM GALL MIDGE, DASINEURA BALSAMICOLA (DIPTERA: CECIDOMYIIDAE)

AbstractNewly emerged adults of several species of parasites of the balsam gall midge were collected in the spring and fall. Biological notes on individual species are given.