<i>Megastigmus strobilobius</i> Ratzeburg, 1848 (Hym., Torymidae): its morphology, life history and economic significance

Skrzypczyńska, M.; Roques, Alain

doi:10.1111/j.1439-0418.1987.tb00550.x

Cited by 9 publications

(12 citation statements)

References 3 publications

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“…For M. strobilobius single‐species attacks occurred only in 4% of the infested cones whereas for the other species this rate varied from 15 to 32%. The low rate for M. strobilobius reflects the fact that it is the latest species to attack spruce cones and in general colonizes only seeds left undamaged by other insects (S krzypczyńska and R oques , 1987).…”

Section: Resultsmentioning

confidence: 99%

“…A common trait of the species association of Norway spruce cones reported in the literature was the dominance of the spruce cone moth C. strobilella (SKRZYPCZYN Â SKA, 1982;SKRZYPCZYN Â SKA and ROQUES, 1987). Likewise for Switzerland, WERME- LINGER et al (1995) showed that this species outnumbers all other seed-feeding insects when reared from spruce cones harvested in the ®ve production regions.…”

Section: Discussionmentioning

confidence: 97%

“…A common trait of the species association of Norway spruce cones reported in the literature was the dominance of the spruce cone moth C. strobilella (S krzypczyńska , 1982; S krzypczyńska and R oques , 1987). Likewise for Switzerland, W ermelinger et al.…”

Section: Discussionmentioning

confidence: 98%

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The effect of spruce cone insects on seed production in Switzerland

Seifert

Wermelinger

Schneider

2000

J Applied Entomology

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In 1989 and 1990, spruce cones were harvested at 29 sites distributed over the five main geographic regions of Switzerland, i.e. Jura, Central Plateau, North, Central and South Alps. The presence of insects and the species‐specific consumption of seeds was determined for each cone by examination of the median longitudinal section. Seven seed‐feeding species (Assara terebrella, Cydia strobilella, Dioryctria abietella, Eupithecia abietaria, Megastigmus strobilobius, Plemeliella abietina, Strobilomyia anthracina) and the spruce cone gall midge Kaltenbachiola strobi were found in the samples. The proportions of infested cones ranged from 36 to 100%. The regions did not show significant differences in terms of infestation rates, whereas differences between sites within the regions were highly significant. Seed loss ranged from 2 to 100%, its geographical distribution exhibiting a similar pattern to the infestation rates. Considering the number of infested cones, C. strobilella was the most abundant species, followed by K. strobi and P. abietina. Cones infested by conospermatophagous species (C. strobilella, D. abietella, E. abietaria) showed higher seed losses than those infested by spermatophages (M. strobilobius, P. abietina). Due to the ubiquitous occurrence of C. strobilella, its high infestation rates and the resulting seed losses caused by its offspring, this species has to be considered as the most important insect seed predator in Switzerland. A multiple linear regression analysis was carried out for each region to simultaneously explore the impact of site and tree variables as well as the effect of insect attack on the yield of viable seeds. The results indicate that site and tree conditions contributed more to the variability of seed yield than insect presence in a cone. The model predicted significant effects of insect attack mainly for cones with total seed numbers that were higher than the average.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 97%

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The effect of spruce cone insects on seed production in Switzerland

Seifert

Wermelinger

Schneider

2000

J Applied Entomology

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“…Because M. strobilobius oviposit at the beginning of seed maturity in fully grown cones (Annila 1981, Skrzypczynska andRoques 1987), they are most likely dependent of fertilized seeds (Þlled seeds) for larval development. This is in contrast to M. spermotrophus Wachtl., which oviposit before seed fertilization and can develop in unfertilized seeds of Douglas Þr by preventing seed abortion (e.g., Niwa andOverhulser 1992, Rouault et al 2004).…”

Section: Figmentioning

confidence: 99%

“…Two other pest species that can cause serious damage in some years are Plemeliella abietina Seitner (Diptera: Cecidomyiidae) and Megastigmus strobilobius Ratz. (Hymenoptera: Torymidae) (Annila 1966, Annila 1973, Skrzypczynska and Roques 1987. Three species (S. anthracina, P. abietina, and C. strobilella) oviposit during ßowering, and three species (D. abietella, E. abietaria, and M. strobilobius) oviposit on cones (Annila 1979(Annila , 1981Roques 1983).…”

mentioning

confidence: 98%

Systemic Insecticide and Gibberellin Reduced Cone Damage and Increased Flowering in a Spruce Seed Orchard

Rosenberg¹,

Almqvist²,

Weslien³

2012

jnl. econ. entom.

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Insects feeding in conifer cones are difficult to control with nonsystemic insecticides. Newly developed systemic insecticides that can be injected into tree trunks may be a possible way of reducing both insect damage and negative side-effects to the surrounding environment, compared with conventional spraying. Several insecticides that could be injected into tree stems were tested on Picea abies (L.) Karst. In one experiment, insecticides (bifenthrin, deltamethrin, abamectin, and imidacloprid) were injected during flowering; in a second experiment two of these insecticides (abamectin and imidacloprid) were injected 1 yr before the expected flowering. In the second experiment insecticide treatment was also combined with treatments with the flower stimulating hormone, gibberellin (GA(4/7)). The only insecticide that reduced damage was abamectin, both after injection during flowering and after injection 1 yr before the expected flowering. Injections with GA(4/7) increased flowering and were as efficient as the conventional application method of drilling but abamectin was not effective in combination with the drilling method. There was no negative effect of the insecticide injections on seed quality. The injections were ineffective against the seed chalcid Megastigmus strobilobius (Ratzeburg), which was found to have an unexpected, negative effect on seed quality. Our results suggest that it may be possible to reduce damage from certain insect species, and to increase flowering by injecting abamectin and GA(4/7) in the year before a cone crop.

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Are traded forest tree seeds a potential source of nonnative pests?

Franić

Prospero

Hartmann

et al. 2019

Ecological Applications

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The international seed trade is considered relatively safe from a phytosanitary point of view and is therefore less regulated than trade in other plants for planting. However, the pests carried by traded seeds are not well known. We assessed insects and fungi in 58 traded seed lots of 11 gymnosperm and angiosperm tree species from North America, Europe, and Asia. Insects were detected by X‐raying and molecular methods. The fungal community was characterized using high‐throughput sequencing (HTS) and by growing fungi on non‐selective agar. About 30% of the seed lots contained insect larvae. Gymnosperms contained mostly hymenopteran (Megastigmus spp.) and dipteran (Cecidomyiidae) larvae, while angiosperms contained lepidopteran (Cydia latiferreana) and coleopteran (Curculio spp.) larvae. HTS indicated the presence of fungi in all seed lots and fungi grew on non‐selective agar from 96% of the seed lots. Fungal abundance and diversity were much higher than insect diversity and abundance, especially in angiosperm seeds. Almost 50% of all fungal exact sequence variants (ESVs) found in angiosperms were potential pathogens, in comparison with around 30% of potentially pathogenic ESVs found in gymnosperms. The results of this study indicate that seeds may pose a greater risk of pest introduction than previously believed or accounted for. A rapid risk assessment suggests that only a small number of species identified in this study is of phytosanitary concern. However, more research is needed to enable better risk assessment, especially to increase knowledge about the potential for transmission of fungi to seedlings and the host range and impact of identified species.

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Megastigmus strobilobius Ratzeburg, 1848 (Hym., Torymidae): its morphology, life history and economic significance

Cited by 9 publications

References 3 publications

The effect of spruce cone insects on seed production in Switzerland

The effect of spruce cone insects on seed production in Switzerland

Systemic Insecticide and Gibberellin Reduced Cone Damage and Increased Flowering in a Spruce Seed Orchard

Are traded forest tree seeds a potential source of nonnative pests?

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