Psyllids as a Potential Source of Heavy Metals for Predators

Abstract

Covariance analysis of fluctuations in local populations of pear psyllids and anthocorid bugs Scutereanu, P.; Lingeman, R.; Drukker, B.; Sabelis, M.W. Abstract. 1. To test whether predatory anthocorids migrate into pear orchards when populations of pear psyllids are building up, a cross-correlation analysis was carried out on their population numbers. Predator and prey population sizes were assessed weekly in 3 consecutive years (1991±93) by sampling pear leaves for eggs and nymphs of psyllids and pear tree branches for adult psyllids, as well as adults and nymphs of predatory anthocorids. The time-series consisted of numbers (per leaf or branch) averaged over preselected pear trees in an orchard and, in addition, over other trees selected along the hedgerows ¯anking the orchard. 2. The ¯uctuations in populations of adult and juvenile anthocorids showed strong cross-correlations with those of the eggs and nymphs of pear psyllids, but less correlation with adults of pear psyllids, as expected based on their increased ability to escape from predation. The psyllids always appeared ®rst on the pear trees, resulting in positive phase shifts. The ®rst peak of adult anthocorids on pear trees was always later than the ®rst peak in the hedgerows, and the ®rst peak of nymphal anthocorids on pear trees was always later than the ®rst peak of adults on these pear trees. In each of the 3 years, anthocorids were rarely observed in the pear orchard during the ®rst part of the growing season (April±June), but during the second half of the growing season (July±August) there was a strong numerical response of the anthocorid populations to increasing population densities of pear psyllids. 3. These results provide support for the hypothesis that the numerical response of the predators to prey density is caused initially by migration of anthocorids into the pear orchard and then by a reproductive response. The migrants originate from the hedgerows and other trees elsewhere, where they feed on aphids during the ®rst part of the growing season.

Differential Uptake, Partitioning and Transfer of Cd and Zn in the Soil−Pea Plant−Aphid System

“…Concentrations of Cd and Zn in pea shoots were higher than those found in wheat shoots grown earlier in the crop rotation in the same plots, but the concentrations of both metals were lower in the pea aphids than in the grain aphids ( Sitobion avenae ) feeding on the wheat crop . In the Psyllidae (jumping plant lice), the concentration of trace metals has been reported to vary significantly among different species, even among those feeding on the same plant species . Psyllidae are phloem-feeding insects in the same suborder as aphids (the Sternorrhyncha).…”

“…Aphids are generally specialist herbivores and therefore different species of aphids are found on different crops. The efficiency of trace metal regulating physiology within arthropods is species specific and can vary significantly, even between closely related species , . Thus, the trace metal accumulation characteristics of the crop plant and its associated aphid species may combine to have an antagonistic or synergistic effect on the transfer of trace metal from the soil to the predator trophic level.…”

Sub-lethal effects of a copper sulfate fungicide on development and reproduction in three coccinellid species

“… Ropek and Para (2002) showed that copper fungicides inhibit the growth and infectivity of Verticillium lecanii , an entomopathic fungus that can be important for aphid control in citrus ( Rondon et al ., 1981 ; Michaud, 1999 ). Glowacka et al . (1997) studied heavy metal loads in 14 species of psyllids (Homoptera: Psyllidae) from polluted regions in Finland and found that wax and honeydew secretions were major routes of copper elimination that largely prevented significant bioaccumulation in these insects.…”

The transfer of trace metals in the soil-plant-arthropod system

“…Indeed, the phylum Arthropoda consists of a diverse range of organisms, which is reflected in the diversity of trace metal concentrations found in the species of this phylum (Dar et al, 2019). This is the case among even closely related species feeding on similar diets and is derived from inter-specific differences in physiology (Glowacka et al, 1997;Janssen et al, 1991;Laskowski and Maryanski, 1993;Rabitsch, 1995;Sá et al, 2008), which results in some species exhibiting a poor ability to regulate internal trace metal concentrations (Dallinger, 1993;Janssen et al, 1991;Kramarz, 1999b). This section examines the physiology of arthropods that affects the transfer and accumulation of trace metals from their food.…”