Systemic insecticide and gibberellin reduced cone damage and increased flowering in a spruce seed orchard.

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.

Reduced offspring production in bark beetleTomicus piniperda in pine bolts baited with ethanol and α-pinene, which attract antagonistic insects.

Bolts of Scots pine,Pinus sylvestris L., attacked by the bark beetleTomicus piniperda (L.) were baited with ethanol and α-pinene to attract antagonistic insects and thereby enhance their detrimental effects on the production of bark beetle progeny. Unbaited and caged bolts were included in the experiments as controls. Attraction of beetles to the bolts and subsequent emergence were estimated using traps. Six phloem-feeding species (potential competitors ofT. piniperda) and four predatory species were caught in significantly higher numbers at the baited bolts than at the unbaited ones. The number of offspring and the productivity ofT. piniperda were four to seven times higher in unbaited bolts than in baited bolts. Exclusion of other insects, by using cages, resulted in a nine-fold increase in the number ofT. piniperda offspring per square meter and productivity (offspring per egg gallery) compared with unbaited, exposed bolts.Hylurgops palliatus (Gyll.) (Scolytidae) andRhagium inquisitor (L.) (Cerambycidae) attacked both the baited and unbaited bolts, whereasAcanthocinus aedilis (L.) (Cerambycidae) andPytho depressus (L.) (Pythidae) reproduced almost exclusively in the baited ones. Large numbers of larvae ofThanasimus (Cleridae) andRhizophagus (Rhizophagidae) emerged from both the baited and unbaited bolts. Adults ofPlegaderus vulneratus (Panzer) andCylister linearis (Er.) (Histeridae) emerged almost exclusively from the baited bolts. The low progeny production ofT. piniperda in the baited bolts was attributed largely to the influence of adults ofRhizophagus andEpuraea (Nitidulidae), and larvae ofThanasimus andA. aedilis.

Methylbutynol effectively replaces methylbutenol, a pheromone component ofIps typographus (L.) (Coleoptera: Scolytidae).

In field experiments in Sweden, the constituent 2-methyl-3-buten-2-ol of the aggregation pheromone of the spruce bark bettleIps typographus (L.) was effectively replaced by 2-methyl-3-butyn-2-ol.