Preference and performance of the hyperparasitoid Syrphophagus aphidivorus (Hymenoptera: Encyrtidae): fitness consequences of selecting hosts in live aphids or aphid mummies

Abstract

1. Theoretical models predict that ovipositional decisions of parasitoid females should lead to the selection of the most profitable host for parasitoid development. Most parasitoid species have evolved specific adaptations to exploit a single host stage. However, females of the aphid hyperparasitoid Syrphophagous aphidivorus (Mayr) (Hymenoptera: Encyrtidae) display a unique and atypical oviposition behaviour by attacking either primary parasitoid larvae in live aphids, or parasitoid pupae in dead, mummified aphids.2. In the laboratory, the correlation between host suitability and host preference of S. aphidivorus on the host Aphidius nigripes Ashmead parasitising the aphid Macrosiphum euphorbiae (Thomas) was investigated.3. The relative suitability of the two host stages was determined by measuring hyperparasitoid fitness parameters (survival, development time, fecundity, sex ratio, and adult size of progeny), and calculating the intrinsic rate of population increase (r m ). Host preference by S. aphidivorus females and the influence of aphid defence behaviour on host selection was also examined.4. Hyperparasitoid offspring performance was highest when developing from hosts in aphid mummies and females consistently preferred this host to hosts in parasitised aphids. Although aphid defensive behaviour may influence host selection, it was not a determining factor. Ecological and evolutionary processes that might have led to dual oviposition behaviour in S. aphidivorus are discussed.

Nitric oxide is an upstream signal involved in the multisignalling network during the Russian wheat aphid resistance response and its application enhances resistance

“…Since the role of NO in the RWA resistance has already been established (Moloi and van der Westhuizen 2014), it would be interesting to know whether exogenous application of NO (SNP) could have any effect on the RWA r m . This parameter has often been used as an index for herbivore performance (Calvitti and Remotti 1998;Buitenhuis et al 2004). In addition, alternative host suitability can be quantified using growth rate parameters, such as the r m (Pucherelli et al 2011).…”

Integrated Pest Management of Aphis spiraecola (Hemiptera: Aphididae) in clementines: enhancing its biological control

“…are polyphagous mummy parasitoids and they may develop as a facultative tertiary parasitoid if they attack a mummy containing hyperparasitoids such as Alloxysta sp., P. villosa and also S. aphidivorus, which has the dual oviposition behavior as explained above. However, mummy parasitoids do not always win the competition with hyperparasitoids (Sullivan, 1972;Buitenhuis et al, 2004). Interestingly, strict mummy hyperparasitoids were less abundant suggesting that they may be competitively inferior.…”

“…The latter category can also develop as facultative tertiary parasitoid if they attack an aphid mummy containing a hyperparasitoid (Müller and Godfray, 1998). Furthermore, it is known that at least one parasitoid species, Syrphophagus aphidivorus (Mayr) (Hymenoptera: Encyrtidae), can have hyperparasitoid and mummy parasitoid development (Sullivan and Völkl, 1999;Buitenhuis et al, 2004; but it is unknown whether it also develops as a tertiary parasitoid. Considering that all modes of attack result in the death of the primary parasitoid, hereinafter we simply refer to all secondary parasitoids as hyperparasitoids.…”

“…S. aphidivorus also develops as a koinobiont endohyperparasitoid that can attack primary parasitoid larvae when aphids are still alive, but prefers to attack the pre-pupae or pupae of the primary parasitoid after the aphid has been killed and mummified (Sullivan and Völkl, 1999;Buitenhuis et al, 2004;. Therefore, at the end of the season it might be harder for Alloxysta sp.…”

Comparación de la abundancia y biodiversidad de artrópodos auxiliares entre parcelas de cultivo ecológico y convencional, en plantaciones de cítricos, caqui y nectarina

“…Lysiphlebus testaceipes (Imenes et al, 2002;Buitenhuis et al, 2004). Microterys nietneri (Motschulsky) ha sido citado sobre diversas especies de cóccidos entre las que se encuentran Coccus hesperidum (Kapranas et al, 2007;Trjapitzin, 2008) y Coccus pseudomagnoliarum (Tena y García-Marí, 2008).…”