Density‐dependent and density‐independent responses of three species of Telenomus parasitoids of hemlock looper eggs

• Published in: Entomologia experimentalis et applicata Vol. 137; no. 3; pp. 296 - 303
• Main Authors: Carleton, Drew, Quiring, Dan, Heard, Steve, Hébert, Christian, Delisle, Johanne, Berthiaume, Richard, Bauce, Eric, Royer, Lucie
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.12.2010; Blackwell
• Subjects: Biological and medical sciences; Biological control; Control; density dependence; egg parasitization; Fundamental and applied biological sciences. Psychology; Geometridae; Hymenoptera; IPM; Lambdina fiscellaria; Lepidoptera; Phytopathology. Animal pests. Plant and forest protection; population regulation; Protozoa. Invertebrates; Scelionidae; sex ratio; Telenomus; Telenomus coloradensis; Canada, Quebec; Canada, Newfoundland and Labrador, Newfoundland; Host parasite relation; Population regulation; Insecta; Biological control; Telenomus; IPM; Lambdina fiscellaria; Sex ratio; Scelionidae; Parasitoid; Entomophagous; Geometridae; Beneficial animal; Oophagous; Arthropoda; egg parasitization; Lepidoptera; Density dependence; Parasitism rate; Hymenoptera; Invertebrata
• ISSN: 0013-8703; 1570-7458
• DOI: 10.1111/j.1570-7458.2010.01065.x

We examined patterns of host exploitation by natural populations of three Telenomus species (Hymenoptera: Scelionidae) parasitizing hemlock looper, Lambdina fiscellaria Guenée (Lepidoptera: Geometridae), eggs in sentinel traps in eastern Quebec and western Newfoundland (Canada). The percentage of eggs parasitized by Telenomus flavotibiae Pelletier and Telenomus coloradensis Crawford in autumn, and by Telenomus droozi Muesebeck in spring either were not or only weakly related to host egg density. In contrast, the percentage of eggs parasitized by T. coloradensis in the spring was positively related to host egg density. Telenomus flavotibiae and T. droozi parasitized eggs in fewer traps than T. coloradensis, suggesting that they were less abundant or less efficient locating host patches. Eggs parasitized by T. droozi only occurred in traps with eggs parasitized by T. coloradensis, suggesting that it may be responding to kairomones emitted by T. coloradensis. In contrast, neither the number nor sex ratio of T. coloradensis emerging from eggs in traps with T. droozi differed from those in traps without this congeneric. Secondary sex ratios of all three species were significantly female biased. Our study suggests that only T. coloradensis has the potential to regulate hemlock looper populations.