Predators impairing the natural biological control of parasitoids

Abstract

A well known case of ineffective natural biological control: the puzzling coexistence of the coffee leaf miner, Leucoptera coffeellum (Guérin-Mèneville), and its natural enemies was analyzed. Despite being a suitable prey to eight parasitoid species and three wasp species, all occurring simultaneously, the coffee leaf miner too often presents populations far above the damaging level for the coffee plantation. It is demonstrated that predatory wasps and parasitoids interact negatively, possibly because predatory wasps kill parasitized miner's larvae. In doing so, predatory wasps indirectly kill parasitoids, thereby impairing the efficacy of the natural biological control. It is warned that biological control programs should be based on knowledge of food web interactions, rather than simply on strategies involving introduction of exotic natural enemies.

Analysis of digestive tract content of the larvae of Polybia scutellaris (White) (Hymenoptera, Vespidae)

“…The presence of arthropod remains, including some items identified as scales and mandibles, indicates that Polybia is a predator, as mentioned in previous works (Bruch 1936;Hunt et al 1987;Willink 1998;De Moura et al 2000;Reis et al 2000;Silva & Jaffe 2002). The adult wasps feed their larvae with chewed-up prey, since the larvae lack chewing mouth parts (Bruch 1936).…”

“…Species of Polybia prey on different arthropod orders (Bruch 1936;Richards 1978;Willink 1998;Silva & Jaffe 2002) and may be potential biological control agents for pests that affect both, human health (Bertoni 1911) and crops (Willink 1998;De Moura et al 2000;Reis et al 2000). They forage on flowers searching for nectar, and produce low amount of honey (Bertoni 1911;Bruch 1936;Tellería 1996;Willink 1998).…”

Suitability of leguminous cover crop pollens as food source for the green lacewing Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae)

“…The use of intercrop plant techniques in coffee crops increased the leaf miner predation by predatory wasps (Amaral et al, unpublished data). Furthermore, the provision of extra food sources such as nectar may also benefit parasitoids (Wackers 2004), which are important natural enemies of coffee pests in Brazil (Reis Jr. et al 2000, Reis et al 2002.…”

Insecticide use and organophosphate resistance in the coffee leaf miner Leucoptera coffeella (Lepidoptera: Lyonetiidae)

“…Predatory wasps are commonly reported as the main natural enemies of L. coffeella in Brazil (Reis & Souza, 1986;Souza et al, 1998). However, it seems that parasitism in this pest species is underestimated due to frequent predation of parasitized larvae (Avilés, 1991;Reis et al, 2000). The interaction between predatory wasps (Brachygastra lecheguana Latreille, Polybia scuttelaris (White) and Protonectarina silveirae (de Saussure) (all Vespidae)) and parasitic wasps (Colastes sp., Eubadizon sp.…”