Vegetation Manipulation Impact on Predator and Prey Populations in Louisiana Sugarcane Ecosystems

Mesure de la ressemblance de la faune utile du poirier avec celle de 43 espèces végétales pour optimiser la composition de haies réservoir d'auxiliaires

“…La prise en compte des divers résultats que nous avons exposés montre qu'il n'est pas utopique d'escompter manipuler spécifi-quement le cortège des auxiliaires aux abords des cultures [11]. Ce sont eux qui, à l'échelle de l'espèce végétale unitaire, possèdent la biodiversité dominante et il existe une spécificité du peuplement par espèce végétale permettant une utilisation orientée [12] ; il est donc possible de repérer les essences qui ont pour la culture visée le maximum d'intérêt [13].…”

Selected Abiotic and Biotic Environmental Stress Factors Affecting Two Economically Important Sugarcane Stalk Boring Pests in the United States

“…Weeds compete more effectively against sugarcane than many short-season row crops to an extent because of sugarcane's relatively wide row spacing (≈1.8 m) and slow seedling growth [116]. Less competitive annual weed species die back when the sugarcane canopy closes overhead [22,117], but uncontrolled annual summer weeds have been associated with reductions in sugarcane stalk density, biomass, and commercial sugar production of up to 24%, 19%, and 15%, respectively [22]. While weeds are clearly stress factors under many circumstances, in wet environments (e.g., southern Louisiana) they are not as likely to create conditions of water deficit stress in sugarcane [94] as they are to compete for sunlight during the early part of the growing season.…”

“…Using stable-activable rare earth elements as tracers to mark (presumably monogyne) S. invicta colonies, Showler et al [122] determined that the discrete foraging territories [120] are substantially smaller in weedy sugarcane plots, permitting denser colonization and that resulted in 60% less D. saccharalis injury to sugarcane stalks than in sugarcane field plots devoid of weed growth. In terms of the natural enemy complex, Louisiana sugarcane fields infested with monocot, dicot, and a mix of both were more diverse in terms of soil surface-and foliage-associated arthropods, including natural enemies of D. saccharalis, than bare-soil systems [117]. Sugarcane systems in Louisiana support ≥84 species of spiders, important egg predators of D. saccharalis [124], in 18 families [125] and spider diversity and abundances are increased by weed growth in sugarcane fields [22,[126][127][128].…”

“…), which attacks the New Guinea sugarcane weevil, Rhabdoscelus obscurus Boisd., in Hawaii [129]. Because uncontrolled weed growth is often deleterious, limited weed habitat "islands" within sugarcane fields [117] or confining weeds to furrows with early season weed control only on the row tops might be ways of conserving S. invicta, spiders, and other arthropods that parasitize and consume D. saccharalis [22].…”

The value of parasitoids in biological control

“…Such effort may take two forms: another biological control agent can be introduced, and/or conditions can be changed to allow optimisation of existing control systems. The details of such activities are beyond the scope of this contribution but in brief may comprise such considerations as ecotypic effects (e.g., Caltagirone 1985;Goldson et al 1992), allomone/ kairomones (e.g., Lewis et al 1975), crop modification, food plants for beneficial insects (e.g., Shahjahnan 1974), cultural practices, and the maintenance of refugia (e.g., Ali & Reagan 1985).…”