The importance of assessing the population structure and biology of psylla species for pest monitoring and management in pear orchards

Abstract

The species of pear sucker, also called pear psylla or pear psyllid, which are destructive insects belonging to the genus Cacopsylla (Hemiptera: Psyllidae) cause substantial damage to pear tree plantations. Two consecutive years of research were conducted on the population structure and biological cycle of psylla in a small, elderly, and unmaintained pear orchard in northern Romania. Of the two identified species (C. pyri L. and C. pyricola Forster), C. pyri dominated the psylla population with a percentage of 77.8-80.1%. Adults of both species emerge from hibernation in the first part of March and produce three generations per year. First-generation adults emerge in the first decade of June, the second generation in the last decade of July, and the third generation in the first decade of September as they enter the hibernation phase. Larvae of the first generation appear in the second half of April, the second generation at the end of June - the beginning of July, and the third generation in the second decade of August. There have been reports of up to 11 adults and 27 larvae per leaf, 9 larvae per petiole, and 14 larvae per fruit. The number of adults captured on yellow sticky traps exposed on the southern side of the tree crown was significantly higher compared to the northern side. Following the intense attack, the well-known cv. ‘Williams’ was heavily affected, pear trees were badly defoliated, blackened, and aged prematurely. The climatic conditions of the two years did not influence the phenology of the pests, but the importance of monitoring psyllids is widely argued, considering that it remains the key to integrated protection programs in pear orchards.

Comparative Analysis of Phenotypic and Molecular Data on Response to Main Pear Diseases and Pest Attack in a Germplasm Collection

“…Even though pathogens and psyllid pressure were lower in the study years than in previous years, when psylla and E. amylovora caused significant damage [ 37 , 42 ], including the total loss of some genotypes, the calculation of DA % levels confirmed the susceptibility of some valuable and widely used cultivars worldwide. Among the new Romanian cultivars, Haydeea stood out, confirming previous findings that its response to biotic stress factors, including psylla, is appropriate [ 41 ].…”

“…Due to the enormous economic interest, numerous procedures have been developed for the evaluation and monitoring of the main pathogenic agents. In the case of harmful insects, the scenario remains the same [ 41 ]. These procedures are of great interest both for orchards, where it is desired to obtain high yields and quality fruits in ecological conditions that are as good as possible for the health of the consumer and the environment, as well as in fruit tree breeding and the development of new cultivars [ 56 ].…”

“…The pear sucker species, also known as pear psylla or pear psyllid, are the most dangerous insects in the genus Psylla (or Cacopsylla , Hemiptera: Psyllidae) [ 99 , 100 ]. They can cause substantial damage to pear tree plantations and have already provoked substantial damage in the HRS area [ 41 , 42 ]. C. pyri L. and C. pyricola Förster were detected in the collection, with C. pyri exhibiting greater dominance in the psylla population.…”

“…or Cacopsylla sp.) were among the pests that were most reported, and they were also examined because of the significant damage they had previously caused in the HRS’s experimental fields and neighbouring areas [ 37 , 41 , 42 ]. The assessment of disease and insect attack was carried out over four years, following the standard methodology recommended by each stressor.…”

“…or Cacopsylla ), which can cause great production losses and even affect the sustainability of orchards [ 37 , 39 , 40 ]. These are the most frequent diseases and pests in Romania, including the fruit-growing areas of Transylvania, a historical region inside Romania’s Carpathian arc [ 37 , 41 , 42 ], as well as in the Republic of Moldova [ 43 , 44 , 45 ]. They cause significant losses in both fruit yield and fruit quality.…”