Living on the Edges: Spatial Niche Occupation of Asian Citrus Psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), in Citrus Groves

Abstract

The spatial niche occupation of the Asian citrus psyllid, Diaphorina citri Kuwayama, 1908, was evaluated to determine its field colonization and food resource exploitation strategies in citrus groves. Mature grapefruit and sweet orange groves were surveyed as part of an area-wide program in 2009–2010 to determine D. citri population densities and between-tree distribution. In both cultivars, significantly more psyllids were found on perimeter trees throughout the study period suggesting a strong edge effect in D. citri distribution in the groves. D. citri densities and infestation levels gradually declined from the edge to the center of grove. Higher numbers of D. citri were recorded on trees located on the east and south sides of the groves than those on the west and north sides. Citrus groves located at the outer edge of the study with at least one side non-surrounded to other citrus groves harbored significantly more D. citri than groves located within the block cluster and entirely surrounded by other groves. In detailed field studies during 2012, infestation of D. citri started from border trees in the grove where possibly one generation is completed before inner trees become infested. In addition, psyllid densities decreased significantly with increasing distance from the grove edge. Using the selection index, D citri exhibited a strong niche occupation preference for border trees.

Quality Matters: Influences of Citrus Flush Physicochemical Characteristics on Population Dynamics of the Asian Citrus Psyllid (Hemiptera: Liviidae)

“…Although total and essential amino acid concentrations were higher in phloem sap during the spring relative to the fall flush cycle (Table 2), this was not accompanied by concomitant higher psyllid densities in spring as shown in Fig 5. A possible explanation for this disparity could be that the spring flush, though nutritionally richer than fall flushes, follows a long psyllid overwintering period—from November to February under South Texas conditions [24]. Therefore, fewer adult psyllids would be available to initiate reproduction during the spring relative to more abundant adults in the fall.…”

“…Young and mature shoots were excised from trees during the fall flush cycle on 23 September 2014 in the experimental block and immediately inserted into aquatubes containing hydroponic solution (General Hydroponics, Sebastopol, CA) to maintain their turgidity. Sétamou and Bartels [24] have previously reported higher D . citri populations during the fall flush cycle (September-October) than any other cycle during the year.…”

“…In citrus, young flush shoots are mostly produced during the discrete flush cycles occurring between post-winter dormancy and early fall in most citrus producing states in the U.S. which often correlate with peaks of ACP density [24]. It has been shown that D .…”

“…It has been shown that D . citri population density on host plants is tightly linked to the presence of young flush shoots on such plants [10,24,25]. Therefore, it is plausible that adult D .…”

Edge-biased distributions of insects. A review

“…Such distribution pattern, especially that of O. lignaria, was linked to the presence of big leaf lupine, Lupinus polyphyllus Lindley (Fabales: Fabaceae), planted along field edges (Sheffield et al 2012). In addition, a study of the spatial distribution of Asian citrus psyllids, Diaphorina citri Kuwayama (Hemiptera: Liviidae), in citrus groves (grapefruit and orange) showed strong season-long edge-biased distributions (Setamou and Bartels 2015).…”