Host suitability, quality and host size preference of Leptomastix epona and Pseudaphycus flavidulus, two endoparasitoids of the mealybug Pseudococcus viburni, and host size effect on parasitoid sex ratio and clutch size

• Published in: Entomologia experimentalis et applicata Vol. 96; no. 2; pp. 149 - 158
• Main Authors: Karamaouna, Filitsa, Copland, Michael J.W.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01-08-2000; Blackwell
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Biological and medical sciences; biological control; clutch size; Demecology; Fundamental and applied biological sciences. Psychology; host size; Leptomastix epona; preference; Protozoa. Invertebrata; Pseudaphycus flavidulus; Pseudococcus viburni; quality; sex ratio; suitability; Host parasite relation; Insecta; Biological control; Coccoidea; Clutch size; Sex ratio; Host suitability; Pest; Parasitoid; Homoptera; Encyrtidae; Arthropoda; Chalcidoidea; Pseudococcidae; Quality; Body size; Hymenoptera; Invertebrata; Host preference
• ISSN: 0013-8703; 1570-7458
• DOI: 10.1046/j.1570-7458.2000.00690.x

Five host size classes which mostly consisted of one host stage (first, second, third instar nymph, young adult and preovipositing adult) of the mealybug Pseudococcus viburni (Signoret) Fernald, 1903 [Hemiptera: Pseudococcidae] were tested for susceptibility and suitability for the solitary parasitoid Leptomastix epona (Walker) Graham, 1969 and the gregarious Pseudaphycus flavidulus (Brèthes) De Santis, 1964 [both of them Hymenoptera: Encyrtidae] in no choice experiments. Hosts larger than 1 mm (third instar) were suitable for the development of the parasitoids. Choice experiments with all the host size classes offered simultaneously showed that L. epona and P. flavidulus are parasitoids of mainly larger hosts (>1 mm, third instar nymphs) therefore the parasitoids exploit the same host range. In L. epona, a faster development and a larger size of wasps occurred in host size class 1.83–2.33 mm (young adult mealybugs) indicating a greater host quality compared to other sizes. Proportion of male offspring decreased with the host size following the host size distribution models. In P. flavidulus there was no effect of host quality (size at parasitism) on developmental time, sex ratio or parasitoid size and fecundity. Larger clutch sizes of P. flavidulus emerged from larger hosts but overall this parasitoid was able to parasitize smaller hosts (<1 mm, second instar nymphs) compared to L. epona. Experience of oviposition for 24 h does not seem to affect host size preference or sex ratio of the offspring in L. epona. Implications of the findings for mass‐rearing and single applications of the parasitoids for the purpose of a biological control programme are discussed.