Predators In Orchards Research Articles

Abundance, interannual variation and potential pest predator role of two co‐occurring earwig species in citrus canopies

AbstractEarwigs are usually considered pest predators in orchards. Because of its worldwide distribution, most research on earwigs focuses on the European earwig Forficula auricularia Linnaeus (Insecta: Dermaptera: Forficulidae). However, very little is known of this species in Mediterranean citrus orchards. Earwigs and aphids were collected monthly during 5 years (2006–2010) from citrus canopies. Two species of earwigs were found: F. auricularia and Forficula pubescens Gené (=Guanchia pubescens), with the latter seldom cited in the literature. The goals of this study were (i) to document the abundance of these two earwig species in Mediterranean citrus canopies; (ii) to determine whether they are positively or negatively associated with each other, or randomly distributed; (iii) to measure the interannual variation of the abundance of both species during a 5‐year period and (iv) to evaluate the potential role of earwigs as pest predators in citrus canopies. As compared to colder regions, F. auricularia active period in citrus canopies in our study site lasted longer. Both species co‐occurred randomly in canopies. In 2006, both species showed approximately the same abundance, but in 2010, F. pubescens abundance in canopies was 28 times greater than that of F. auricularia. The potential role of earwigs as pest predators is higher in the Mediterranean than in other colder regions, because of the longer active period. F. auricularia is a sedentary generalist predator, already present in citrus canopies at the onset of most pest outbreaks, while F. pubescens arrived later to the canopies, but most likely was abundant enough to contribute in the control of citrus pests.

Persistence, phytotoxicity, and management of arsenic, lead and mercury residues in old orchard soils of New York State

Lead arsenate was used for pest control in fruit orchards for many years in the United States, and its residues remain in most of these soils. Since arsenic and lead are toxic and only slightly mobile in soils, an analytical survey was conducted in 1993 to determine the concentrations of these elements persisting in soil samples from 13 older and newer orchards in New York State. Concentrations of arsenic and lead ranged, respectively, from 1.60 to 141 and from 1.48 to 720 (ppm, dry wt). Significant ( P < 0.01, n = 13) pairwise correlations were observed among concentrations of these elements: As vs. Pb r = 0.97), As vs. Hg (r = 0.79), and Pb vs. Hg (r = 0.83). Despite previous reports of phytotoxicity to fruit trees, elevated arsenic concentrations did not significantly reduce the dry weights of apple ( Malus domestica) seedlings grown in pasteurized soil from these orchards. The general environmental effects and best management strategies for arsenic and lead in orchard soils are discussed including phytotoxicity of arsenic and its uptake and accumulation in plants, ingestion by small mammal herbivores and their predators in orchards, and ways to minimize potential adverse effects on humans.