Karamaouna, F., & Copland, M.J.W. 2008a Life-table parameters and internal competition - A comparative evaluation of the parasitoids Leptomastix epona and Pseudaphycus flavidulus as biocontrol agents of the mealybug Pseudococcus viburni.. Proceedings of the XI International Symposium on Scale Insect Studies, Oeiras, Portugal, 24-27 September 2007. ISA Press Lisbon, Portugal 322 pp.

Notes: Leptomastix epona (Walker) and Pseudaphycus flavidulus (Brethes) (both Hymenoptera: Encyrtidae) are endoparasitoids of the mealybug Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae). Leptomastix epona is a solitary parasitoid, which is native of Europe whereas P. flavidulus is gregarious and originates in the Neotropical region (Argentina and Chile) (Noyes, pers. comm.). Life table parameters of the parasitoids were estimated in small and large hosts (1-1.8 mm and 1.8-3.3 mm, third-instar nymphs and adult females respectively) at 26°C in the laboratory with a view to determine the comparative efficacy of the two species as biological control agents of P. viburni. Pseudaphycus flavidulus had a slightly higher intrinsic rate of natural increase (rm = 0,08-0,13) than L. epona (rm = 0,07-0,12) when either small or large mealybugs were available. However, destructive host feeding on hosts smaller than 1 mm (second-instar nymphs) by L. epona, which is not measured in the calculation of rm, increased the parasitoid's efficiency (Karamaouna & Copland, 2000). Both parasitoids achieved a greater intrinsic rate of natural increase in large mealybugs compared with small ones but L. epona produced more female offspring per generation (R) than P. flavidulus in large hosts and P. flavidulus produced more female offspring per generation than L. epona in small hosts. Subsequently, the potential of both parasitoid species to control the mealybug seems to improve with the increase of host size but P. flavidulus may prove to be more efficient than the solitary parasitoid earlier in the season when mainly small hosts are present. Interspecific host discrimination and multiparasitism were examined in laboratory experiments at two time intervals (0-3 h and 24 h) between succeeding ovipositions of the parasitoid species in relation to prospects for multiple introductions. Leptomastix epona did not discriminate between unparasitized hosts and already parasitized hosts by P. flavidulus. Nevertheless, P. flavidulus discriminated between unparasitized hosts and hosts which had been parasitized 0-3 hours earlier by L. epona but oviposit without discrimination in hosts heterospecifically parasitized 24 hours previously. When multiparasitism occurred 0-3 hours after the first oviposition, L. epona was a superior competitor regardless of whether oviposition by L. epona took place before or followed oviposition by P. flavidulus. However, when the time interval between the two ovipositions was 24 hours, the probability of the offspring of P. flavidulus winning the competition with L. epona increased.