Mechanical ecology of fruit-insect interaction in the adult Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae)

Role of Fruit Epicuticular Waxes in Preventing Bactrocera oleae (Diptera: Tephritidae) Attachment in Different Cultivars of Olea europaea

“…Indeed, a reduction of traction force of B. oleae on a hydrophobic surface compared with a hydrophylic one was clearly visible: the safety factor was higher on hydrophilic glass (contact angle = 19.94 ± 0.41 • ) than on hydrophobic glass (contact angle = 112.62 ± 1.50 • ). A significant decrease in the attachment force on artificial surfaces with an increasing surface contact angle has been reported also in another Diptera species, C. capitata [32], and in different other insect species belonging to Coleoptera, such as Gastrophysa viridula (De Geer) (Coleoptera, Chrysomelidae) [22], Cylas puncticolis Boheman (Coleoptera, Brentidae) [56], Cryptolaemus montrouzieri Mulsant, (Coleoptera, Coccinellidae) [57] and Coccinella septempunctata L. (Coleoptera, Coccinellidae) females [24,58] as well as to Heteroptera, such as N. viridula [55]. These results are explained by the reduction of the attachment force on microstructured substrates owing to the reduced role of the adhesive fluid in generation of capillary forces, by either too low or too strong affinity of the insect adhesive fluid to the microstructured substrates [59].…”

“…This suggested that the contact angle of the host plant might rule the attachment behavior of species on different surfaces in relation with adaptation [60]. In this regard, as above reported, the comparison between the attachment ability of two Tephritidae species, such as the polyphagous C. capitata [32] and the monophagous B. oleae, is particularly interesting. However, the similar results regarding the attachment ability to smooth hydrophilic and hydrophobic surfaces (the same glass surfaces were tested) obtained in these two species do not confirm the hypothesis (at least in Tephritidae) that the effect of the substrate chemistry on insect attachment could depend on insect species and its level of specialization.…”

“…The importance of 3D EWs in decreasing surface wettability is known [2,8], and their role in reducing insect attachment to the plant surface has been studied in many insect and plant species using different experimental approaches [27][28][29][30][31] (see also reviews in [10][11][12]). In our recent investigation, testing the attachment ability of females of another Tephritidae, the Mediterranean fruit fly Ceratitis capitata Wiedemann (Diptera: Tephritidae) to fruits of various host plants characterized by different surface morphology (smooth, hairy, waxy) [32], a strong reduction in attachment ability was recorded on Prunus domestica, compared with other tested fruit surfaces, due to the dense and regular 3D EW coverage. This last in P. domestica is composed of numerous, very short, thin-walled tubules oriented at different angles to the surface, making the fruit surface superhydrophobic.…”

“…The reduction of insect adhesion of B. oleae could be linked better to the roughness hypothesis [42,47], stating that wax projections reduce insect adhesion owing to the surface microroughness, similar to the effect of microrough polishing paper with 0.3-1.0 µm asperity sizes minimizing insect pad contact areas due to small surface irregularities. Such a reduction has been demonstrated in many different insect species [44,[48][49][50][51][52][53][54][55], among which the Mediterranean fruit fly C. capitata [32].…”

Attachment devices and the tarsal gland of the bug Coreus marginatus (Hemiptera: Coreidae)

“…Note that the unguitractor plate (UP), the claws (CL), the pretarsal apodeme (PR), the tarsal apodeme (TA), the basipulvilli (BP) and the dorsal portion of the pulvilli are sclerotised, while the lamina (LM) located below and around the unguitractor plate and the ventral side of the pulvilli (VS) contain high proportion of resilin. T3 third tarsomere (Roth and Willis 1952;Clemente and Federle 2008;Schmitt and Betz 2017), the stick insect Carausius morosus Sinéty (Phasmatodea) (Scholz et al 2008), the grasshopper Tettigonia viridissima (L.) (Slifer 1950;Henning 1974;, the locusts Schistocerca gregaria (Forskål) (Kendall 1970) and Locusta migratoria (L.) (Orthoptera) (Perez Goodwyn et al 2006), Karoophasma biedouwense Klass (Mantophasmatodea) (Eberhard et al 2009) and the honeybee (Hymenoptera) (Federle et al 2001) and with hairy attachment pads, such as the fly Ceratitis capitata (Diptera) (Salerno et al 2020) and the beetles Philonthus marginatus (Müller) (Betz and Mumm 2001) and Gastrophysa viridula (De Geer) (Coleoptera) (Eimüller et al 2008). The specialised cuticle on the ventral side of adhesive pads Fig.…”