Source or Sink? The Role of Residential Host Plants in Asian Citrus Psyllid Infestation of Commercial Citrus Groves

Abstract

Citriculture landscapes in the U.S. are typically habitat mosaics of commercial groves interspersed with residential areas supporting a variety of unmanaged citrus. Diaphorina citri the vector of Candidatus Liberibacter asiaticus, the causal agent of Huanglongbing feeds on citrus in both habitats. We postulated that residential citrus function as a ‘source’ of D. citri that infest groves, functioning as sinks. Here we report on an experimental mark-release-recapture study conducted at the interface of a residential neighborhood and groves. Adult D. citri marked with colored fluorescent powders were released in both habitats (n = 15,300) and their movement within and between milieus monitored. Although the recapture rate of marked psyllids was very low (0.23%), the results were instructive. Most of the recaptured psyllids in residential trees (84.6%) were released within that habitat. In contrast, approximately half of the marked psyllids recovered in groves were released in residential areas. Of all the recaptured psyllids, about 40% changed habitats, but the change was skewed toward movement from residential to grove habitat. These data strongly suggest that there is a constant exchange of D. citri adults between the two habitats, with residential citrus trees functioning as a source habitat of psyllids. The further the residential trees are located from groves, the less likely they will serve as sources of D. citri. Hence, to reduce the risks of citrus grove colonization by D. citri, new groves should be established away from residential habitats where possible, and psyllid management practices must also be implemented in residential habitats.

Cry1Ba1-mediated toxicity of transgenic Bergera koenigii and Citrus sinensis to the Asian citrus psyllid Diaphorina citri

“…an alternative host plant that is highly attractive to the psyllid but is not a host for CLas or CLam. As psyllids move into citrus groves from neighboring smaller habitats ( 15 ), trap plants surrounding the grove would function to intercept ACP prior to grove entry. We and others have previously reported on B. thuringiensis -derived pesticidal proteins with toxicity against ACP ( 16 , 17 ), and the production of transgenic Indian curry leaf plant, Bergera koenigii expressing one of the psyllid-active proteins, Cry1Ba1 ( 18 ).…”

Grove-level analysis of titer and prevalence of “CandidatusLiberibacter asiaticus” andWolbachiainDiaphorina citri,vector of citrus Huanglongbing

“…Abandoned groves have also been shown to maintain high D. citri populations that travel frequently between managed and abandoned areas (Sétamou et al 2022; Boina et al 2009) with equally high C Las titers and infection rates as alive and managed groves (Hall 2018). Prior to 2010, Tiwari et al (Tiwari et al 2010) studied the D. citri-C Las infection rate and found 1.9 % in abandoned and 1.2 % in managed grove populations while the mean C Las Cq value was 32.52 in abandoned and 25.95 in managed groves.…”

“…Abandoned groves have also been shown to maintain high D. citri populations that travel frequently between managed and abandoned areas (Sétamou et al 2022;Boina et al 2009) with equally high CLas titers and infection rates as alive and managed groves (Hall 2018).…”

An optical system to detect, surveil, and kill flying insect vectors of human and crop pathogens

“…Adult D . citri are typically 2.7–3.3 mm long 158 and can disperse widely across landscapes 159 – 161 . Growers rely heavily on insecticides to control D .…”