Powdering of egg nests with brochosomes and related sexual dimorphism in leafhoppers (Hemiptera: Cicadellidae)

Abstract

Leafhoppers from 16 New World genera currently placed in the tribes Proconiini (13) and Cicadellini (2) of the subfamily Cicadellinae, in the subfamily Phereurhininae (1), and one undescribed genus exhibit a suite of morphological specializations associated with a unique type of maternal care. The females produce a specific type of brochosomes (secretory particles manufactured in the Malpighian tubules of most leafhoppers and usually forming a non-sex-specific hydrophobic coating of the integument), which they store prior to oviposition on their forewings in the form of pellets and then apply as a powdery coating to the egg clusters placed under the epidermis of leaves or, in one genus, exposed. The function of the brochosome coating is unknown, but may include protection of eggs against parasitoids and pathogens, and facilitating gas exchange. Observations on several species from the genera Phera, Homalodisca, Oncometopia, Quichira, Cuerna, and the undescribed genus are reported, complementing scanty existing data on this behaviour. Its taxonomic occurrence is described for the first time based on study of collections, where ready-tooviposit females are occasionally preserved with pellets of brochosomes on their forewings. A comprehensive survey of associated female-specific structural modifications is presented based on examination of c. 80 predominantly Neotropical species. These modifications include (1) production of modified brochosomes (2) modified setation of the forewing area upon which pellets of such brochosomes are placed, and (3) elongation of the metathoracic tibial macrosetae, which transfer the brochosomes onto the egg nest. The traits are absent or rudimentary in males. The specialized brochosomes display remarkable interspecific diversity and can be used for taxonomic identification of eggs. Egg-powdering apparently has evolved as a modification of the anointing and grooming behaviours involved in making coatings of integumental brochosomes in most leafhoppers. Morphological similarity, extending to characters not related to oviposition, suggests that all genera containing 'powdering' species may form a single lineage, but this hypothesis yet needs to be tested by phylogenetic analyses. Several such genera include species displaying powdering-associated traits and species lacking these, suggesting multiple independent losses or origins of powdering. This peculiar kind of maternal care provides an interesting model for study of the evolution of novel functional complexes of traits.

Adult Tea Green Leafhoppers, Empoasca onukii (Matsuda), Change Behaviors under Varying Light Conditions

“…Cleaning is an essential behavior that enhances hydrophobicity through the coating of their integuments with brochosomes, thus protecting the adults from being washed off from leaves by water [19, 20]. Locomotion activities, such as walking, jumping and flying, are considered important elements of survival as they are usually related to avoiding danger (for instance, enemies), foraging, finding places to stand and social interactions [21, 22]. Searching is crucial especially during courtship as the male leafhopper continually flies among plants until it finds a mate.…”

Egg Brochosomes of Proconiini (Hemiptera: Cicadellidae, Cicadellinae) species associated with cultivation of grapevines

“…Comment -These are similar to the M. consolida egg brochosomes found in the present study, however, they can be easily distinguished for their conspicuous, significantly larger reticula, and for the lack of depressed areas; the species has egg brochosomes very similar to Pseudophera contraria (Walker), especially in relation to the reticulum shape and arrangement discussed by Rakitov (2004).…”

“…Egg brochosomes generally display an elongate shape, but spherical shapes can be found in some species of the following genera: Homalodisca; Oncometopia, and Tapajosa (Rakitov, 2004). This species has egg brochosomes very similar to those of Tapajosa spinata Young, discussed by Rakitov (2004).…”

Egg Stage of Homalodisca vitripennis and Homalodisca liturata (Hemiptera: Cicadellidae): Ovometrics, Embryonic Development, and Nonparasitic Mortality

“…One such method is the use of the powdery material, referred to as brochosomes, deposited by female Homalodisca during oviposition. Al-Wahaibi (2004), based on work by Hix (2001) and Rakitov (2000Rakitov ( , 2002Rakitov ( , 2004, outlined a compound microscope method for differentiating the two species using the shape of the brochosomes deposited by females on the surface of egg masses. De Azevedo Filho and Carvalho (2005) and De Azevedo Filho et al (2008) used variation in the morphology of brochosomes (discerned using scanning electron microscopy) to produce keys to differentiate among seven and eight species of Proconiini leafhoppers occurring, respectively, on citrus and grape vines in Brazil, respectively.…”

“…One possible method for identiÞcation of egg masses of the two Homalodisca species might be quantitative assessment of egg size and egg clutch size. Hix (2001) and Rakitov (2004) developed a method of differentiating eggs of the two species based on microscopic examination of the shape of brochosomes that form a powdery covering that the female deposits over egg masses after they are laid. However, this method is laborious and time-consuming because it requires examination under a high-magniÞcation compound microscope after making sure a sufÞcient amount of clean brochosomes is placed on a microscope slide.…”