Entomologia Experimentalis et Applicata (2001) 99, 331-339
Brigitte Dorn, Letizia Mattiacci, Anthony C. Bellotti and Silvia Dorn (2001)
Host specificity and comparative foraging behaviour of Aenasius vexans and Acerophagus coccois, two endo-parasitoids of the cassava mealybug
Entomologia Experimentalis et Applicata 99 (3), 331-339
Abstract: Two encyrtid parasitoids, Aenasius vexans Kerrich (Hymenoptera: Encyrtidae) and Acerophagus coccois Smith (Hymenoptera: Encyrtidae), were compared for their degree of dietary specialisation and the impact this has on their foraging strategies. Both parasitoid species are significant for biological control of the cassava mealybug, Phenacoccus herreni, Cox and Williams (Homoptera: Sternorrhyncha) a major Latin American pest of cassava, Manihot esculenta Crantz, an important root crop. Host acceptance and parasitism were analysed in seven mealybug species (with different levels of polyphagy) occurring in and around cassava fields. Results demonstrate that, in this ecosystem, An. vexans is a specialist for P. herreni while Ac. coccois is a generalist on the first and second trophic level. Of the seven mealybug species, P. herreni and P. madeirensis Green were the most acceptable hosts for Ac. coccois, followed by Ferrisia virgata Cockerell. Ac. coccois did not accept the other four mealybug species.
The foraging and oviposition behaviour of individual parasitoids was observed in bioassays with cassava leaves infested by P. herreni. The two species used different strategies to locate their host. Aenasius vexans spent significantly more time walking and standing on an infested leaf and examined a host longer than did Ac. coccois. Acerophagus coccois, in contrast, spent more time for oviposition. As a consequence An. vexans parasitised more hosts in a given time than did Ac. coccois. Because the rate of offspring production of the two species did not differ, we conclude that the gregarious Ac. coccois's strategy to deposit several eggs at once might compensate for its relatively low number of ovipostitions, compared with the solitary An. vexans. These findings suggest that, given the advantages and limitations of each species, a multi-species approach to biological control of P. herreni may yield best results.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Anthony C. Bellotti, Silvia Dorn, Brigitte Dorn
Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution
