Cavichiana bromelicola

Results View in CoL

Description of egg

Length 1.40–1.51 mm.

Not fertilised or in the preoviposition stage of Al-Wahaibi and Morse (2009). Narrow flattened ellipse-shaped (sausage or cigar-like; Figure 1 View Figure 1 (a)), pale yellow immediately after dissection of the abdomen, shiny, somewhat translucid, so that cytoplasm material and yolk are visible; surface smooth. SEM: external surface of chorion covered by delicate layer that is possibly derived from the ovary ( Figure 1 View Figure 1 (b)); this layer is easily damaged and peeled off. Anterior end (where the head of the embryo develops) narrower and more pointed than posterior end; ventral surface with apical angle and longitudinal keel located at anterior portion; no other distinctive structures apparent (head cap and eye spot).

Descriptions of nymphs

First stadium nymph

Total length 1.70–1.94 mm (see Table 1 View Table 1 for additional measurements).

Head, in dorsal view, approximately as long as wide, well produced anteriorly; crown ( Figure 2 View Figure 2 (a)) with median length approximately equal to interocular width and 0.50 of transocular width; without any kind of apical projection. Crown with anterior margin broadly round; with carina at transition to face; surface without conspicuous sculpturing or setae; with postfrons ( Figure 3 View Figure 3 (a)) distinct, somewhat rugose; vertex ( Figure 3 View Figure 3 (a)) smooth; frontogenal suture ( Figure 3 View Figure 3 (a,b)) distinct, delimiting frontal area and separating vertex from frons; coronal (= epicranial) suture ( Figure 3 View Figure 3 (a)) adjacent to ecdysial line, distinct. Antennal ledge, in dorsal view, not protuberant, with lateral carena; antenna greater than or approximately equal to total length of first stadium nymph; scape ( Figure 3 View Figure 3 (f,g)) cylindrical and smooth; pedicel ( Figure 3 View Figure 3 (f,g)) cylindrical, mostly smooth but with some scale-like sculpturing ( Figure 3 View Figure 3 (f-h)) irregularly distributed; flagellum ( Figure 3 View Figure 3 (f)) setiform with sensilla trichodea located basally. Compound eye ( Figure 3 View Figure 3 (a, b)), in dorsal view, oblong, longer than wide; ommatidia round ( Figure 4 View Figure 4 (a)); interommatidial spaces distinct, with sensilla trichodea ( Figure 4 View Figure 4 (a,c)) and s. coeloconica ( Figure 4 View Figure 4 (a,d,f)) irregularly distributed; length of compound eye varying from 0.24 to 0.26 mm. Ocelli absent; ocellar maculae inconspicuous, located on elevated areas at anterior vertex area. Frons ( Figure 3 View Figure 3 (b,i)) subtriangular; surface mostly smooth, with sensilla campaniformia and s. trichodea ( Figure 3 View Figure 3 (b,c)) irregularly distributed; cibarial muscle impressions ( Figure 3 View Figure 3 (b)) distinct; in lateral view, with slight protuberance on inferior portion. Subgenal suture ( Figure 3 View Figure 3 (i)) distinct, delimiting lorum area. Lorum ( Figure 3 View Figure 3 (i)) smooth, its main portion located laterally to clypeus, approximately semicircular, with sensilla trichodea irregularly distributed. Gena ( Figure 3 View Figure 3 (b,d,i)) smooth, located next to loral and frontogenal sutures and fused inferiorly with maxillary plate, extended upwards around posterior margin of compound eye; with sensilla trichodea ( Figure 3 View Figure 3 (d)) close to compound eye, s. campaniformia and s. placodea ( Figure 3 View Figure 3 (d,e)) irregularly distributed. Maxillary plate ( Figure 3 View Figure 3 (i)) smooth, located laterally to lorum, with distinct Evans organ ( Figure 3 View Figure 3 (i,j)). Epistomal suture ( Figure 3 View Figure 3 (b,i)) inconspicuous. Clypeus ( Figure 3 View Figure 3 (b,i,k)) smooth, located below frons, with lateral margins round and apex convex; in lateral view, continuing profile of frons, with sensilla campaniformia and s. trichodea irregularly distributed on apical portion, especially on lateral margins. Labrum ( Figure 3 View Figure 3 (k)) smooth, flat, located at apex of clypeus, covering base of labium, narrow and triangular, surface with microtrichia irregularly distributed. Labium ( Figure 3 View Figure 3 (k,l)) connected basally to cervical membrane, tube-like, three-segmented, extending as far posteriorly as insertion of middle legs; surface with sensilla basiconica and s. trichodea irregularly distributed; pair of apical sensory fields with conspicuous s. basiconica ( Figure 3 View Figure 3 (l)).

Thorax ( Figure 2 View Figure 2 (a)). Pronotum, in dorsal view, subrectangular, distinctly wider than long, maximum width less than transocular distance of head; anterior margin slightly produced anteriorly; lateral margins convergent anteriorly, with posterior portion narrowly round and slightly produced lateroposteriorly; posterior margin slightly concave, with median emargination; surface smooth, with irregularly distributed microsetae. Mesonotum and metanotum with smooth surface, sensilla trichodea irregularly distributed; posterior margin of mesonotum arched; wing pads indistinct, covered by irregularly distributed microsetae. Hind legs with tibia with four rows of dispersed macrosetae.

Abdomen. With eight visible segments plus pygofer (tergite of segment IX) and anal tube (strongly modified and reduced segments X and XI, the latter bearing the anal style). Broad basally, gradually tapering posteriorly ( Figure 2 View Figure 2 (a)); first two segments reduced in relation to others; microsetae forming two irregular rows along posterior portion of segments, in dorsal view; median longitudinal line of segments without microsetae. Pygofer with irregularly distributed microsetae. The sexes cannot be differentiated in this stadium based on the external morphology.

Colour ( Figure 2 View Figure 2 (a)). Ground colour of dorsum greyish white. Crown with anterior portion light brown to brown; pair of light brown to brown irregular stripes originating from anterior margin, adjacent to coronal suture; pair of light brown to brown arched stripes originating from lateral margin and ending next to aforementioned irregular stripes; pair of light brown to brown spots on posterior margin. Compound eyes dark red. Frons, gena and maxillary plate greyish white; superior portion of frons with brown to dark brown large spot, with stripe extending to median portion; posterior margin of maxillary plate, clypeus, and labrum darkened; labium greyish white. Pronotum without pair of contrasting orange longitudinal stripes. Mesonotum and metanotum somewhat hyaline; metanotum with pair of light brown to brown large spots near median portion and pair of light brown spots on anterior portion near lateral margins. Lateral and ventral portions of thorax, abdomen and legs mostly greyish white; abdomen, in dorsal view, with or without three pairs of light brown to brown spots on anterior portion, near posterior margin of metanotum; pygofer brown to dark brown.

Second stadium nymph

Total length 2.54–2.77 mm (see Table 1 View Table 1 for additional measurements).

Head, in dorsal view, wider than long; crown ( Figure 2 View Figure 2 (b)) with median length approximately 0.90 of interocular width and 0.50 of transocular width. Length of compound eyes varying from 0.30 to 0.34 mm; ommatidia subquadrangular ( Figure 4 View Figure 4 (b)),closer to one another than in previous stadium. Other features of head as described above for first stadium.

Thorax ( Figure 2 View Figure 2 (b)). Pronotum more developed in relation to head than that of first stadium, subrectangular; lateral margins broadly round, not lateroposteriorly projected as in first stadium. Mesoscutum and apex of scutellum also more developed than those of first stadium. Other features of thorax as described above for first stadium.

Abdomen. Microsetae forming two or three irregular rows along posterior half of segments, in dorsal view. General form and other features of abdomen as described for first stadium. Not yet possible to differentiate the sexes based on external features.

Colour ( Figure 2 View Figure 2 (b)). Anterior portion of crown brown to dark brown, with greyish white slender central line and two pairs of greyish white spots near coronal suture; pair of brown to dark brown spots on posterior portion of crown, near coronal suture. Pronotum with pair of distinct, contrasting irregular parallel longitudinal orange stripes near central line, extending from anterior to posterior margin. Other features of colour much as described above for first stadium.

Third stadium nymph

Total length 3.12–3.76 mm (see Table 1 View Table 1 for additional measurements).

Head. Crown ( Figure 2 View Figure 2 (c)) with median length approximately 0.85 of interocular width and 0.50 of transocular width. Length of compound eyes varying from 0.40 to 0.46 mm; ommatidia slightly hexagonal ( Figure 4 View Figure 4 (c)), located very close to one another. Other features of head as described for previous stadia.

Thorax ( Figure 2 View Figure 2 (c)). Pronotum subrectangular but more developed anteriorly than in previous stadia; its length greater than in second stadium; median longitudinal line of pronotum, along ecdysial line, without microsetae. Mesonotum also more developed than in previous stadia; lateroposterior angles expanded, covering anterior third of metanotum. Wing pads clearly visible from this stadium onwards, with irregularly distributed microsetae; wing pads of mesonotum covering those of metanotum. Hind legs with higher density of macrosetae than fore or middle legs. Other features of thorax as described for previous stadia.

Abdomen. Rudiments of the external male and female terminalia (gonapophyses) are visible from this stadium onwards, so that it is possible to clearly distinguish the sexes. Gonapophyses of both sexes consist of three pairs of triangular plates. In females, left and right parts of external plates are separated from one another along their whole length (see Figure 5 View Figure 5 (b), fourth instar). Male external gonapophyses are separated from one another for about half their length or less (see Figure 5 View Figure 5 (a), fourth instar). Gonapophyses I (from segment VIII), II, and III (both from s. IX) are destined to become, respectively, the first ovipositor valvulae, second ovipositor valvulae and the gonoplacs (ovipositor sheaths or third valvulae) of females. In males, the gonapophyses (all from s. IX) form the subgenital plates (the basal genital valve is not yet differentiated), connective and aedeagus (basal and distal portions of the intromittent organ, respectively), and styli (or parameres). Pygofer with irregularly distributed macrosetae. General form and other features of abdomen as described for previous stadia.

Colour ( Figure 2 View Figure 2 (c)). Pair of light orange to orange arched stripes extending from anterior margin to median portion of crown. Other features much as described in previous stadia.

Fourth stadium nymph

Total length 4.26–4.88 mm (see Table 1 View Table 1 for additional measurements).

Head. Crown ( Figure 2 View Figure 2 (d)) with median length approximately 0.75 of interocular width and 0.45 of transocular width. Length of compound eyes varying from 0.53 to 0.57 mm; ommatidia subhexagonal ( Figure 4 View Figure 4 (d)), without space between them. Other features as described for previous stadia.

Thorax ( Figure 2 View Figure 2 (d)). Pronotum more developed anteriorly than in previous stadia; its length greater than in third stadium. Mesonotum shorter than metanotum; wing pads of mesonotum extended beyond half-length of metanotum. Hind legs with tibial anterodorsal row of macrosetae interspaced by microsetae. Other features of thorax as described in previous stadia.

Abdomen. Microsetae forming three irregular rows along posterior half of segments, in dorsal view. Terminalia distinct and more sclerotised than in third stadium ( Figure 5 View Figure 5 (a,b)). Other features as described for previous stadia.

Colour ( Figure 2 View Figure 2 (d)). Much as described for previous stadia.

Fifth stadium nymph

Total length 5.49–5.73 mm (see Table 1 View Table 1 for additional measurements).

Head. Crown ( Figure 2 View Figure 2 (e)) with median length approximately 0.90 of interocular width and 0.50 of transocular width; anterior margin narrowly round. Ocellar maculae ( Figure 3 View Figure 3 (a)) distinct, highlighted by pair of round areas, located anterad of line between anterior eye angles. Length of compound eyes varying from 0.54 to 0.59 mm. Other features as described for previous stadia.

Thorax ( Figure 2 View Figure 2 (e)). Pronotum subrectangular but more developed anteriorly than in previous stadia; its length greater than in fourth stadium; anterior margin broadly round. Mesonotum length equal to or greater than length of metanotum. Wing pads of mesonotum covering almost completely those of metanotum. Other features as described for previous stadia.

Abdomen. Microsetae distributed in three or four irregular transverse rows at posterior half of segments ( Figure 2 View Figure 2 (e)), except in median longitudinal line, in dorsal view. Terminalia well developed and sclerotised. Other features as described for previous stadia.

Colour ( Figure 2 View Figure 2 (e)). Wing pads of mesonotum with or without pair of white semicircular spots. Other features much as described for previous stadia.

Material examined

South-eastern Brazil, Rio de Janeiro State, Bromeliad Collection of Jardim Botânico do Rio de Janeiro (JBRJ). Approximately 250 C. bromelicola nymphs were studied in this paper. Samplings were carried out from December 2015 to August 2018, as follows: 10 December 2015, 9 March 2016, 15 June 2016, 22 July 2016, 13 September 2016, 16 January 2017, 13 February 2017, 20 March 2017, 27 March 2017, 24 April 2017, 15 May 2017, 26 June 2017, 31 July 2017, 28 August 2017, 4 September 2017, 25 October 2017, 8 November 2017, 14 November 2017, 22 November 2017, 27 November 2017, 11 December 2017, 18 December 2017, 23 January 2018, 27 February 2018, 27 March 2018, 25 April 2018, 22 May 2018, 21 June 2018, 31 July 2018, 29 August 2018 (unfortunately, all material was lost due to the fire at the Museu Nacional on 2 September 2018). New samplings were carried out on 15 July 2019 and 19 September 2019 (DZRJ, MNRJ).

Biological notes

During the sampling work at the Bromeliad Collection of Jardim Botânico do Rio de Janeiro, a large number of C. bromelicola nymphs were collected (approximately 250), predominantly in the spring and summer (November to April). Study of this material suggests that C. bromelicola is a multivoltine species, with more than three generations per year, but additional studies are needed to test this supposition.

Despite our great effort, we have not been able to locate C. bromelicola eggs in the leaves of the bromeliads. The eggs studied here were found after dissection of the abdomen of adult females ( Figure 1 View Figure 1 ); they are morphologically similar to the preoviposition eggs of the sharpshooter Homalodisca vitripennis (Germar, 1821) described by AlWahaibi and Morse (2009) and to the eggs of H. insolita (Walker, 1858) described by Pollard (1965); they also resemble the eggs of Macropsis fumipennis (Gillette and Baker, 1895) (Macropsinae) and Orientus ishidae (Matsumura, 1902) (Deltocephalinae) , both described by Valley and Wheeler (1985). The absence of the head cap and the eye spot in the C. bromelicola eggs indicates that they were not fertilised or were in the undifferentiated stage of Al-Wahaibi and Morse (2009).

Only a small number of first and second stadium nymphs of C. bromelicola were collected, possibly in part because of their small size (1.70–1.94 and 2.54–2.77 mm, respectively, see Table 1 View Table 1 ). Also, these nymphs seek shelter between the bromeliad leaves near the water tank, making their sampling somewhat difficult. They were collected by active search inside the leaf rosette of the bromeliads, using an entomological aspirator. We also observed that, after moulting, nymphs seek shelter on the leaves near the soil, remaining protected until hardening of their new exoskeleton.

Adults and nymphs of C. bromelicola were collected on the following bromeliads from the Bromeliad Collection: Alcantarea imperialis (Carrière) Harms , Alcantarea glaziouana (Leme) J.R. Grant , Alcantarea sp. , Goudaea ospinae (H. Luther) W. Till and Barfuss , Guzmania sp. , Neoregelia compacta (Mez) L.B. Smith , Neoregelia sp. , and Vriesea hieroglyphica (Carrière) E. Morren. Additional details on the host bromeliads of C. bromelicola are provided in Table 2 View Table 2 . Curiously, many nymphs were collected on G. ospinae , an endemic species from Colombia that was donated to the Bromeliad Collection. It is thus clear that the trade of bromeliads can serve as a means for the artificial dispersion of the sharpshooter.

In addition to C. bromelicola , Portanus restingalis Felix and Mejdalani, 2016 ( Cicadellidae : Aphrodinae : Portanini) was also observed feeding on bromeliads at the Jardim Botânico do Rio de Janeiro ( Felix et al. 2020). Four species of spiders were found in the bromeliads and they may be possible predators of C. bromelicola and P. restingalis : Argiope argentata (Fabricius, 1775) (Araneidae) , Gasteracantha cancriformis (Linnaeus, 1758) (Araneidae) , Selenops melanurus Mello-Leitão, 1923 (Selenopidae) , and Theridion sp. (Theridiidae) . Interestingly, a Chrysopidae larva was observed carrying a dead C. bromelicola adult on its dorsum.

During the sampling period, a systemic insecticide of the neonicotinoid chemical group was used to control Lepidoptera caterpillars in the Bromeliad Collection. Unfortunately, the use of this insecticide caused a great reduction in the number of C. bromelicola adults and nymphs. However, we were still able to find specimens in bromeliads located in areas of the Jardim Botânico adjacent to the Bromeliad Collection.