Susceptiblity of crabapple cultivars to attack by the codling moth

A repository block of ornamental crabapples containing 87 cultivars was left unsprayed and evaluated for resistance to the codling moth, Laspeyresia pomonella (L.). Although there were considerable differences in susceptibility, none of the cultivars was resistant to codling moth attack. A number of trees escaped injury from the first generation, but all showed entries from the second generation in August

Control of the Apple Clearwing Moth, Synanthedon myopaeformis, with Tree-Trunk Applications of Reduced-risk Insecticides, Nematodes and Barriers

Apple clearwing moth (ACM), Synanthedonmyopaeformis Borkhausen (Lepidoptera: Sesiidae), wasdiscovered in an apple orchard in Cawston, British Columbia in 2005.  This xylophagous, invasive Europeanspecies has become a serious problem in high-density apple orchards wheresize-controlling rootstocks are attacked by the wood-boring larvae.  Seven screening trials with reduced-riskinsecticides for conventional (seven treatments) and organic apple production (threetreatments) were established in two commercial high-density mixed-variety appleplantings in Cawston.  Our objectiveswere (1) to screen several new synthetic insecticides having novel chemistriesthat purportedly have reduced risks, (2) to evaluate use of several organically-approvedspray materials, including nematodes, and (3) to compare the efficacy ofvarious products when applied at different times during the growing season.  Single, hand-gun sprays delivering treatmentsin 2000 L of water ha-1 at 200 psi were applied as curative sprays targeting mature larvae inrootstock-scion graft unions in May and October 2008, and June 2009.  Among seven treatments tested, only theinsect growth regulator, Rimon® 10 EC (10% novaluron), at 2.4 L a.i.ha-1, caused significant reductions in adult emergence compared withuntreated controls in all experiments.  Whenapplied twice as preventativetreatments during flight of male ACM in 2008, Altacor®, Belt®,Delegate™ and Rimon all caused significant reductions in adult emergence thefollowing year; Rimon caused the greatest reduction (-96.4%).  In a similar 2009 trial only Rimon reducedpopulations the following year.  One curative or two preventative applications of the organic materials, Entrust®,Crocker’s Fish Oil®, or Purespray Green Oil™, at anyspray timing, did not control ACM.  The nematode,Steinernema feltiae (Filipjev) (1×105infective juvenile nematodes / 100 ml of water / tree) provided significant controlof ACM in one spring 2008 trial.  In two 2009nematode-only experiments, a sawdust paste tree-trunk barrier applied over nematodeapplications made either in May or August, caused significant reductions in emergenceof ACM adults.  Curative tree-trunk spraysof Rimon 10 EC at the tested rate are recommended for control of ACM inconventional apple orchards.  There is noeffective organic control for ACM at this time, but tree-trunk barriers andnematodes may warrant further study

Compatability of parasitism by Bonnetia comta (Fallén), Lydella thompsoni Herting, and Macrocentrus grandii Goidanich, and a bacterial, viral, or microsporidian infection in larvae of Agrotis ipsilon (Hufnagel) and Ostrinia nubilalis (Hubner)

Laboratory assays were conducted to study the impact of pathogenic infections of black cutworm (BCW), Agrotis ipsilon (Hufnagel) and European corn bearer (ECB), Ostrinia nubilalis (Hubner) on their parasitoid species Bonnetia comta (Fallen) (BCW), and Lydella thompsoni Herting and Macrocentrus grandii Goidanich (ECB). Host microsporidian infections had detrimental effects on all three parasitoids. Vairimorpha necatrix (Kramer) and Vairimorpha sp. both decreased the number of B. comta able to pupate from BCW hosts, the days required for adult eclosion, and the weights of the puparia. These effects increased with an increase in the intensity of the host infection. Nosema pyrausta (Paillot) and Nosema sp. within ECB hosts reduced eclosion of adult L. thompsoni by 36 and 100%, respectively. Nosema sp. was found to infect most ECB tissues as opposed to the limited infection caused by N. pyrausta. Lydella thompsoni maggots consume most of the ECB host tissues; therefore the more severe impact that the Nosema sp. had on the parasitoid could be explained by the difference in the number of spores consumed. Similarly, V. necatrix, which infects primarily the ECB host fat body tissue, and Nosema sp., had more detrimental effects on M. grandii developing in infected hosts than did the N. pyrausta. Again, it appeared that the impact of the microsporidian on the parasitoid was a function of the pathology of the pathogen within the host and the developmental biology of the parasitoid resulting in essentially a dosage response. Vairimorpha necatrix- and N. pyrausta-infected female M. grandii were unable to transovarially transmit these pathogens to their offspring.;A nuclear polyhedrosis virus from a mint looper, Rachiplusia ou (Guenee) (RoMNPV) had no detrimental effect on B. comta or L. thompsoni developing in RoMNPV-infected BCWs or ECBs, except indirectly, when the virus killed the hosts before the parasitoids were able to emerge. The RoMNPV polyhedral inclusion bodies were found only in the gut lumen of these parasitoids.;Bacillus thuringiensis Berliner subspecies kurstaki, although not pathogenic to BCW larvae, did reduce B. comta parasitism in treated hosts. Bacillus thuringiensis spores or crystals caught in the intersegmental membranes of the BCW host cuticle may have been encountered and ingested by B. comta planidia entering the hosts, causing them to die.</p

Compatability of parasitism by Bonnetia comta (Fallén), Lydella thompsoni Herting, and Macrocentrus grandii Goidanich, and a bacterial, viral, or microsporidian infection in larvae of Agrotis ipsilon (Hufnagel) and Ostrinia nubilalis (Hubner)

Laboratory assays were conducted to study the impact of pathogenic infections of black cutworm (BCW), Agrotis ipsilon (Hufnagel) and European corn bearer (ECB), Ostrinia nubilalis (Hubner) on their parasitoid species Bonnetia comta (Fallen) (BCW), and Lydella thompsoni Herting and Macrocentrus grandii Goidanich (ECB). Host microsporidian infections had detrimental effects on all three parasitoids. Vairimorpha necatrix (Kramer) and Vairimorpha sp. both decreased the number of B. comta able to pupate from BCW hosts, the days required for adult eclosion, and the weights of the puparia. These effects increased with an increase in the intensity of the host infection. Nosema pyrausta (Paillot) and Nosema sp. within ECB hosts reduced eclosion of adult L. thompsoni by 36 and 100%, respectively. Nosema sp. was found to infect most ECB tissues as opposed to the limited infection caused by N. pyrausta. Lydella thompsoni maggots consume most of the ECB host tissues; therefore the more severe impact that the Nosema sp. had on the parasitoid could be explained by the difference in the number of spores consumed. Similarly, V. necatrix, which infects primarily the ECB host fat body tissue, and Nosema sp., had more detrimental effects on M. grandii developing in infected hosts than did the N. pyrausta. Again, it appeared that the impact of the microsporidian on the parasitoid was a function of the pathology of the pathogen within the host and the developmental biology of the parasitoid resulting in essentially a dosage response. Vairimorpha necatrix- and N. pyrausta-infected female M. grandii were unable to transovarially transmit these pathogens to their offspring.;A nuclear polyhedrosis virus from a mint looper, Rachiplusia ou (Guenee) (RoMNPV) had no detrimental effect on B. comta or L. thompsoni developing in RoMNPV-infected BCWs or ECBs, except indirectly, when the virus killed the hosts before the parasitoids were able to emerge. The RoMNPV polyhedral inclusion bodies were found only in the gut lumen of these parasitoids.;Bacillus thuringiensis Berliner subspecies kurstaki, although not pathogenic to BCW larvae, did reduce B. comta parasitism in treated hosts. Bacillus thuringiensis spores or crystals caught in the intersegmental membranes of the BCW host cuticle may have been encountered and ingested by B. comta planidia entering the hosts, causing them to die

Control of the Apple Clearwing Moth, Synanthedon myopaeformis, with Tree-Trunk Applications of Reduced-risk Insecticides, Nematodes and Barriers

Apple clearwing moth (ACM), Synanthedonmyopaeformis Borkhausen (Lepidoptera: Sesiidae), wasdiscovered in an apple orchard in Cawston, British Columbia in 2005.  This xylophagous, invasive Europeanspecies has become a serious problem in high-density apple orchards wheresize-controlling rootstocks are attacked by the wood-boring larvae.  Seven screening trials with reduced-riskinsecticides for conventional (seven treatments) and organic apple production (threetreatments) were established in two commercial high-density mixed-variety appleplantings in Cawston.  Our objectiveswere (1) to screen several new synthetic insecticides having novel chemistriesthat purportedly have reduced risks, (2) to evaluate use of several organically-approvedspray materials, including nematodes, and (3) to compare the efficacy ofvarious products when applied at different times during the growing season.  Single, hand-gun sprays delivering treatmentsin 2000 L of water ha-1 at 200 psi were applied as curative sprays targeting mature larvae inrootstock-scion graft unions in May and October 2008, and June 2009.  Among seven treatments tested, only theinsect growth regulator, Rimon® 10 EC (10% novaluron), at 2.4 L a.i.ha-1, caused significant reductions in adult emergence compared withuntreated controls in all experiments.  Whenapplied twice as preventativetreatments during flight of male ACM in 2008, Altacor®, Belt®,Delegate™ and Rimon all caused significant reductions in adult emergence thefollowing year; Rimon caused the greatest reduction (-96.4%).  In a similar 2009 trial only Rimon reducedpopulations the following year.  One curative or two preventative applications of the organic materials, Entrust®,Crocker’s Fish Oil®, or Purespray Green Oil™, at anyspray timing, did not control ACM.  The nematode,Steinernema feltiae (Filipjev) (1×105infective juvenile nematodes / 100 ml of water / tree) provided significant controlof ACM in one spring 2008 trial.  In two 2009nematode-only experiments, a sawdust paste tree-trunk barrier applied over nematodeapplications made either in May or August, caused significant reductions in emergenceof ACM adults.  Curative tree-trunk spraysof Rimon 10 EC at the tested rate are recommended for control of ACM inconventional apple orchards.  There is noeffective organic control for ACM at this time, but tree-trunk barriers andnematodes may warrant further study