Psyllids in Natural Habitats as Alternative Resources for Key Natural Enemies of the Pear Psyllids (Hemiptera: Psylloidea)

Abstract

The pear psyllids (Cacopsylla spp.; Psylloidea) comprise ~24 species of sap-feeding insects distributed in Europe, temperate Asia, and (as introductions) in the Americas. These pear-specialized insects are among the most damaging and difficult to control pests in orchards. Biological control increasingly is being used to replace or partially replace insecticidal management of pear psyllids. Many key natural enemies of pear psyllids regularly occur in non-orchard habitats on native plants. The presence of beneficial species both in orchard and non-orchard habitats (here referred to as “spillover”) has prompted suggestions that native plants and their associated psyllids should be conserved as alternative resources for natural enemies of pear psyllids. The expectation is that the natural enemies will move from those habitats into psyllid-infested orchards. This review shows that psyllids in native habitats are important resources for several key predators and parasitoids of pear psyllids. These resources are critical enough that some beneficials exhibit an almost nomadic existence as they move between plant species, tracking the seasonal appearance and disappearance of psyllid species. In contrast, other natural enemies show minimal or no spillover between orchard and non-orchard habitats, which likely is evidence that they exhibit limited movement at best between orchard and non-orchard habitats. To show conclusively that spillover also indicates that a beneficial species disperses between native habitats and orchards requires difficult research on insect movement. This review concludes with a brief discussion of these difficulties and possible solutions.

Potent and selective ‘genetic zipper’ method for plant protection: innovative DNA psyllidicides againstTrioza alacrisFlor based on short unmodified antisense oligonucleotides targeting rRNA of the pest

“…The main problems connected with the use of chemical insecticides are the emergence of resistance and lack of selectivity in action. Of note, psyllids in native habitats are an important alternative resource for key natural enemies of pest psyllids (Horton, 2024). Oligonucleotide insecticides, due to their unique sequences of nitrogenous bases, are able to provide both, selectivity in action and avoidance of target-site resistance by insect pests (if conservative sequences of target genes are used).…”