Are avian predators effective biological control agents for rodent pest management in agricultural systems?

Worldwide rodent pests are of significant economic and health importance. Controlling rodent pests will, therefore, not only benefit food security but also human and animal health. While rodent pests are most often chemically controlled, there is increased interest in biological control through avian predation. A rich body of research has addressed the impact of avian predators on wild rodent populations, but little is known about the effectiveness of avian predators as biological control agents of rodent pests in agricultural systems. In this study, we systematically reviewed research that investigated different aspects of avian predation on rodent pest populations in order to increase our understanding of the impact and effectiveness of avian predation on rodent pests. Several avian predators (Tyto alba, Elanus axillaris Falco tinnunculus, F. cenchroides, Bubo bengalensis, Buteo rufinus) were commonly cited in the biological control of rodents; however, barn owls (T. alba) are the most cited species (86% of studies). We found some support that the use of avian predators produced positive, measurable effects where increased presence of avian predators tended to lower rodent pest numbers, resulting in lower crop damage. However, our review highlighted several shortcomings related to research on avian predation of rodent pests. First, research concerning rodent pest control through avian predation was limited (1.86 articles per year). Secondly, we found that studies lack statistical rigor to detect and measure change in rodent pest species abundance. Finally, the majority of studies were short term and therefore not able to evaluate long term sustainable rodent pest population suppression. We suggest that current shortcomings could be adequately addressed with control-treatment studies that quantitatively investigate the effects of avian predation on rodent pest populations and agricultural impact. Such research could help develop recommendations regarding the use of avian predators in rodent pest management

Transmission electron microscopy study of the microstructure and dislocation configuration in Al \u3c inf\u3e 67 Co \u3c inf\u3e 8 Ti \u3c inf\u3e 25

The microstructure and dislocation configuration of the Al67Co8Ti25 intermetallic compound were observed and studied by transmission electron microscopy. It was shown that the matrix of the alloy with nominal composition Al67Co8Ti25 had the L12 crystal structure, and a small amount of second phase present in part of the grain boundaries was identified to be TiAl2Co. Two types of dislocation were observed to exist in this alloy: ⟨101⟩-type superdislocations and ⟨100⟩-type ordinary dislocations. The former were frequently observed to dissociate into partials bounding some planar faults, while ⟨100⟩ dislocations were usually single dislocations or dislocations in a dislocation row. © 1993 Taylor & Francis Group, LLC