Alternative techniques to study characters of the genitalia in Lepidoptera

Abstract

-The present note aims to describe two alternative methods for observing genitalia in Lepidoptera. The fi rst one provides means to examine both male and female genitalia without spoiling the scales of the abdomen, preserving it attached to the thorax and aesthetically similar to an unexamined specimen. The second one provides ways of observing certain characters on the male genitalia in a non-destructive way, and does not depend on time-consuming removing and dissection of the abdomen. It is expected that the presented techniques will help on morphological studies and on identifying similar species which consistently differ in genitalic armatures.KEY WORDS: Morphology, identifi cation, valva, uncusAs noted by Niculescu (1976), many authors recognize the importance of the genitalia as the most informative specifi c character in the Lepidoptera, especially the valvae of the male genitalia due to their variation (Fox 1953). It is well known that closely related species or species under similar selective pressures tend to show similar patterns, and those patterns are often obscured by intraspecifi c variations and/ or seasonal forms, thus adding an element of confusion in identifi cation. Several of these species are only distinguished by genitalic preparations. The present scientifi c note aims to make known two alternative techniques to access these structures.The first technique provides means to remove both male and female genitalia without spoiling the scales of the abdomen, preserving it attached to the thorax and aesthetically similar to an unexamined specimen, while allows morphologic study. The researcher should carry out the following steps: 1) detach the abdomen from the thorax and sink it in distilled water for some 18h to 24h; 2) transfer the abdomen to a petri dish with paraffi n wax on the bottom fi lled with water; 3) fi x the abdomen sideways with thin insect pins (size 0 or 1) and cut it antero-posteriorly through the pleura using ophthalmologic scissors (Fig 1a), and cut throughout the inter-segmental membrane between the seventh and eight segments in females or between the eighth and ninth segments in males (Fig 1b); 4) open the abdominal cavity, fi xing the tergites and sternites with thin insect pins on the paraffi n wax; 5) using a thin forceps, remove the genitalia and with it the abdominal content. After removed, the genitalia may be further prepared as usual. Be careful while removing membranous parts of the genitalia, especially the female's bursa copulatrix which is very easily damaged. To preserve defi nitively after dissection, put the genitalia in a glycerin-fi lled small test tube, which should be pinned with the insect afterwards; 6) put the emptied abdomen resting on absorbing paper for a while, and then mount it with insect pins on polystyrene foam. Take it to a low temperature stove (circa 30 o C) for a couple of days until it dries completely, then reattach it to the thorax using white glue.This method has proven to be useful for several taxa of Papilionoidea and Hesper...

Identifying Memphis: A comprehensive and comparative description of the immature stages and natural history of Memphis acidalia victoria (H. Druce, 1877; Lepidoptera: Nymphalidae)

“…A useful method for the determination of male species is the direct observation of the tip of the genitalia under a stereoscopic microscope (Dias et al . ). Using this method, M .…”

“…The genitalia were directly examined (Dias et al . ) before being dissected and soaked in heated 10% potassium hydroxide solution for approximately 5–10 min. The genitalia were then further examined under a stereoscopic microscope, and illustrations prepared with a camera lucida or digital photographic camera.…”

“…c, g, k, o, s = 1 mm.Yellow arrows-distal spine of the valva; red arrow-spined sacculus; grey arrows-strongly keeled and straight uncus. species is the direct observation of the tip of the genitalia under a stereoscopic microscope (Dias et al 2010d). Using this method, M. acidalia victoria can be distinguished from most similar sympatric species of Memphis by the presence of a medial spine at the tip of the valva, absent in all subspecies of M. moruus, M. oenomais, and in M. philumena corita (Fig.…”

DNA Barcoding Simplifies Environmental Risk Assessment of Genetically Modified Crops in Biodiverse Regions

“…Furthermore, despite development of non-destructive anatomical examination protocols for some taxa, morphological identification of arthopods frequently requires destructive removal of internal organs for reliable diagnosis [59]. In these cases, it may not be possible to verify identification at a later date through re-examination of the same specimen, should the accuracy of diagnosis be in doubt or else should taxonomic revision generate fresh ambiguity (e.g.…”

Morphology of Immature Stages and Adults of Helicoverpa Armigera

“…Correct identification of the pest is an essential requisite for devising effective IPM strategies (Chakravarty et al, 2018). The external morphological characters of life stages (Ranjith and Chellappan, 2015), wing colour patterns (Ethier and Despland, 2015), and genitalia morphology (Pogue, 2004;Dias et al, 2010), have been found to be highly informative and useful for species recognition in lepidopteran insects. Though much has been published concerning general morphology, biology and behavioural aspects of H. armigera (King, 1994;Ali et al, 2009;Kingsolver et al, 2011;Tang et al, 2016, Queiroz-Santos et al, 2018, studies offering details on key identification features of this species from India are still limited and scattered.…”