Monalonion velezangeli, (Carvalho & Costa) (Carvalho & Costa)

Noboa, Michelle, Castillo, Carmen, Carvajal, Vladimir, Merino, Jorge, Gaona, Pablo, Viteri, Pablo & Park, Chan Hwan, 2024, First record of Monalonion velezangeli (Hemiptera: Miridae) affecting avocado and cherimoya (Annona cherimola) as new hosts in Ecuador, Zootaxa 5519 (3), pp. 423-429 : 425-428

Damage and Host Plants Nymphs and adults of M. velezangeli were found on the leaves ( Fig. 1A ) and fruits of avocado trees ( Fig. 1B ). Punctures from the insect caused welt-like lesions on the branches, commonly concentrated at the tip ( Fig. 1C ). Lesions on the fruits reached sizes of two to five mm in diameter. Initially, they were welts, then depressions formed in the pericarp of the fruit ( Fig. 1B ). When the puncture is recent or fresh, there is oxidation of perseitol, a seven-carbon alcoholic compound released in the injured areas of the avocado ( Hoddle & Hoddle 2008), generating a solid white exudate in the form of splashes ( Fig. 1D ). When the puncture is older than 10 days, it turns into a dark circular spot with necrotic tissue and a depression is observed.

The attack occurs both on small fruits of two cm in equatorial diameter and large fruits over five cm in diameter. Analyzing the lesions caused by M. velezangeli , it was quantified that in seven days, an adult makes an average of 45.5 lesions or punctures per fruit. Consequently, the damage that a single insect can cause is of high impact on the productivity of the orchard. In the physiologically mature fruit, there is no evidence of pulp damage; however, the scarred lesions on the skin are evident as defects, affecting the commercial value of the fruit.

The damage caused by M. velezangeli on the fruit of cherimoya ( A. cherimola ) is characterized by dark depressions of one to two mm in diameter ( Fig. 2E ). The appearance of the damage varies when the puncture is fresh or old ( Fig. 2F ). The bug’s puncture likely facilitates the colonization of black saprophytic fungi by causing wounds in the fruit’s epidermis.

Taxonomic Description of M. velezangeli

Adults of M. velezangeli ( Fig. 3A ) have a shiny black head with segmented antennae covered with small black hairs and divided into four antennomeres. The first is glabrous compared to the other three ( Fig. 3B ). The rostrum extends beyond the first pair of legs and has four segments ( Fig. 3C ).

The thorax and abdomen are variable in color from black to orange. The pronotum and scutellum also show a diversity of tones ( Fig. 3D, 3E ). Intraspecific variability shows that colors vary among specimens of the same species ( Carvalho 1972). There is also variability in coloration among adults depending on sex, with variations between black and red ( Giraldo et al. 2010). For this reason, color is not a good descriptor for species determination ( Gamboa et al. 2020). The hind legs are toned from chestnut to black, with femurs thickened toward the distal part, a creamy white band toward the middle, and densely hairy tibiae ( Fig. 3F, 3G ).

The hindwings are membranous in texture, light cream to transparent in color; the hemelytra (forewings) are variably colored from ochre to black in the corium; depending on the individual’s morphotype, they present one or two spots inside the cell with the main vein near the cuneus and two outside the cell near the red vein ( Fig. 3H, 3I ), which matches the description by Giraldo et al. (2010) and differs from what Carvalho & Costa (1998) reported: two spots inside the cell near the cuneus and another outside the cell near the vein.

The male genitalia of the analyzed specimens match the description by Carvalho & Costa (1988) presenting a generic type aedeagus with a large membranous portion ( Fig. 4A ) and an elongated basal plate. The left paramere is approximately twice the size of the right one, with a rounded apex ( Fig. 4B ). The right paramere is small, simple, and curved with a sharp apex ( Fig. 4C ). The genitalia description in the reference is brief, and it seems the variations of this structure within the genus Monalonion are subtle and sometimes nonexistent, with no taxonomic descriptions clearly separating the species; however, we recognize that visually they resemble those described by Carvalho & Costa (1988) and Giraldo et al. (2010). To clarify the taxonomic status of the genus Monalonion, Gamboa et al. (2020) proposed a nomenclature for the male genitalia as a taxonomic tool, detailing the structures that compose this reproductive organ ( Fig. 4A ), but no differentiated descriptions for each species are presented, only a general one for the genus Monalonion .

The identification of Monalonion species lacks sufficient taxonomic tools, and studies for understanding the interspecific and intraspecific morphological variations within the genus are scarce ( Gamboa et al., 2020). Consequently, molecular studies of all described species and their holotypes are necessary to clarify the variation of the morphological characteristics to determine whether they are one or more species and understand the phylogeny of the genus.

Regarding the molecular results of the present study, all specimens were similar. Amplicons of approximately 700 bp were observed ( Fig. 4D ), suggesting that coloration is not an indicator of genetic differences, at least for the cytochrome oxidase I (COI) gene region. These assembled sequences were compared with the NCBI GenBank nucleotide database, and the matches were null for this species; therefore, this report constitutes the first molecular reference of Monalonion velezangeli in the GenBank (Accession numbers: PQ046647.1, PQ046646.1 PQ046645.1, PQ046644.1), which can be used for future research.

Figures

FIGURE 1. A. Nymph of M. velezangeli on an avocado plant. B. Adult of M. velezangeli on an avocado fruit. C. M. velezangeli bites on young avocado branches. D. Damage to small fruit of 2.2 and 2.4 cm in polar diameter.

FIGURE 2. Confirmation test for M. velezangeli damage in avocado and cherimoya. A. Healthy fruit. B. Fruit confined with an adult M. velezangeli. C. Fruit of 6.3 cm in polar diameter with damage due to the bug’s puncture. D. Fruit confined with an adult M. velezangeli. E. Fruit affected by M. velezangeli. F. Fruit with recent pitting (left) and fruit with old pitting (right) and beginnings of a saprophytic fungal infection.

FIGURE 3. A. M. velezangeli adult in vivo. B. Antennae with four segments. C. Rostrum of M. velezangeli with its four segments. D and E. Coloration diversity in the M. velezangeli pronotum (P), scutellum (S). F and G. Coloration diversity in the legs of M. velezangeli and creamy white strip in the middle of the femurs (CWS). H and I. Coloration diversity in forewings in cuneus (Cu) and corium (Co), spots inside (Si) and outside the vein in the membrane (Me).

FIGURE 4. Structures of the male genitalia of M. velezangeli. A.Aedeagus: teak opening (at), teak (te), endosoma (en), seminal duct (sd), phallus base (bp), captured process. B. Left paramere: basal region (br), paramere body (pb), apical region (ar). C. Right paramere: basal region (br), paramere body (pb), apical region (ar). D. Agarose gel with PCR products for the COI fragment of five of the collected samples (MM= molecular weight marker, CN = negative control).