Effect of ground cover vegetation on the abundance and diversity of beneficial arthropods in citrus orchards

Abstract

The effect of ground cover upon the communities of beneficial arthropods established in the canopy of lemon trees was investigated, by comparing three ground-cover management treatments applied: RV, resident vegetation; S, sowed selected species; and BS, bare soil by controlling weeds with herbicide. Over two consecutive years, arthropod communities in the tree canopy were sampled periodically by beating and suction techniques. Significantly higher numbers of beneficial arthropods were found in the RV and S treatments in comparison with bare soil. Spiders and parasitoid wasps were the two most common groups, representing, respectively, 70% and 19% of all catches in beating samples and 33% and 53% in suction samples. For the RV and S treatments, significant seasonal deviations from the bare soil treatment were observed using principal response curves. Similar seasonal patterns were observed over the two years. The RV and S treatments showed significant positive deviations from the BS treatment in late spring and summer, accounted for the higher numbers of parasitoid wasps, coccinelids and lacewings present. By contrast, the seasonal deviations observed for the spider community differed from those of the remaining arthropods. During late winter and early spring, the RV and S treatments presented a higher abundance of spiders in the tree canopy, in comparison with bare soil, whereas in the summer significantly more spiders were found in the bare soil treatment. Spider movements between tree canopy and ground vegetation layers may justify this result.

Abundance, movements and biodiversity of flying predatory insects in crop and non-crop agroecosystems

“…Thus, our first hypothesis based on the supposition that lacewings would find more complementary food from the many flowering weeds of the ground vegetation, which was supported on previous studies that found high abundance of many predatory insects at ground vegetation level (e.g., Bianchi et al 2006;Silva et al 2010) was wrong. There may be several reasons explaining this behavior: the comparative higher disturbance at the ground vegetation level (mowing, fruit picking, etc), the better refuge against wind and extreme temperatures that shelterbelts represent (wooded habitats provide more moderate microclimate (Forman and Baudry 1984)), and/or the higher abundance of non-flying competing predators in the above ground layer (some of them can act also as predators of lacewings).…”

Impactos do controle de plantas daninhas e da aplicação de herbicidas em inimigos naturais

“…Weeds benefit different arthropods, providing habitat, additional sources of food (pollen and nectar), favorable microclimate for the development of natural enemies, parasitoids and other insects, shelter and refuge from predators and to overcome disturbances caused by agricultural practices (Jonsson et al, 2008;Silva et al, 2010). Natural enemies benefit from the resources available for these plants, which favors their efficiency as pest regulators (Landis et al, 2000).…”

“…These plants are a source of shelter, refuge, food and favorable microclimate for the development of different insects and breeding sites for predators and parasitoids (Steinbauer et al, 2006;Silva et al, 2010). However, weed control can alter the abundance and flora of different plant species, which can damage the associated arthropods (Landis et al, 2000;Albajes et al, 2009).…”

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

“…Según estos autores el manejo del hábitat se puede abordar a nivel de la parcela, de la explotación o del paisaje. En los últimos años se ha publicado una gran cantidad de estudios sobre el papel que pueden cumplir los distintos componentes del sistema agrícola, tales como las cubiertas vegetales (Bugg y Waddington, 1994;Wyss et al, 1995;Sirrine et al, 2008;Gámez-Virués et al, 2009;Silva et al, 2010), los márgenes de los cultivos (Rieux et al, 1999;Holland y Fahrig, 2000;Olson y Wäckers, 2007), los corredores vegetales (Nicholls et al, 2001) y, en general, las denominadas áreas no cultivadas (Gurr et al, 2003;Boller et al, 2004;Bianchi et al, 2006). …”