Abrupt Geographical Transition between Aposematic Color Forms in the SpittlebugProsapia ignipectus(Fitch) (Hemiptera: Cercopidae)

Abstract

Over most of its range populations of the spittlebugProsapia ignipectus(Fitch) (Hemiptera: Cercopidae) are monomorphic for black dorsal coloration. At the far northeastern margin of the species range in Maine, a cluster of populations is monomorphic for the presence of traverse orange dorsal lines against a black background. The narrow gap separating monomorphic black and monomorphic lined populations is less than 10 km wide, shows no evidence of a hybrid zone, and is without consequential physical barriers or ecological breaks. This sharp and unexpected division of color forms seems to have persisted for at least 90 years. It appears to be the sharpest divide ever recorded between geographically adjacent populations monomorphic for alternative aposematic color forms. About 45 kilometers to the southwest of this dividing line, three closely situated populations, surrounded by monomorphic black populations, are polymorphic for the two color forms. These observations are at variance with several expectations for aposematic species: (1) that local populations will be monomorphic for warning coloration, (2) that adjacent populations monomorphic for different local color forms will be linked by populations with mixed or hybrid forms, and (3) that geographic boundaries between contrasting aposematic color forms should be temporally unstable.

Wolbachiain the spittlebugProsapia ignipectus:Variable infection frequencies, but no apparent effect on host reproductive isolation

“…Collection sites were on the verges of public rights of way or privately owned land. In two cases (New Vineyard and New Portland) they correspond to sites reported in Thompson and Carvalho (2016).…”

“…Prosapia ignipectus (Fitch) (Hemiptera: Cercopidae) is one of about 14 species of Prosapia and one of two commonly found in the USA, the other being its sister species P. bicincta (Say) (Hamilton, 1977). P. ignipectus occurs in southern Ontario, Canada and the northeastern USA from Minnesota to Maine (Hamilton, 1977(Hamilton, , 1982Peck, 1999;Carvalho and Webb, 2005;Thompson and Carvalho, 2016). These species vary in male genital morphology and in associations with host plants, with P. ignipectus monophagous on the late season C4 perennial grass Schizachyrium scoparium (Little bluestem) (Hamilton, 1982;Thompson, 2004) and P. bicincta polyphagous on a variety of C4 grasses, but not including Little bluestem (Fagan and Kuitert, 1969;Thompson, 2004).…”

“…About 45 km southwest of this abrupt transition between aposematic color forms, three other P. ignipectus populations were found to be polymorphic with both black and lined formsthese populations are surrounded by monomorphic black populations. It has been hypothesized that Wolbachia determined RI may contribute to preservation of the sharp Maine morphological contact zone (Thompson and Carvalho, 2016).…”

Prey colour biases in jumping spiders (Habronattus brunneus) differ across populations

“…The chemical defences of these two groups are poorly understood (Lin, ; Wood, , ), but at least some species such as Umbonia crassicornis (oak treehopper) and Platycotis viltata (thorn bug) have striking aposematic colouration and are rejected by lizards as prey on the basis of taste (Wood, , ). Indeed, there is extensive evidence for aposematism in many related families of larger and better studied hemipterans (e.g., frog hoppers/spittle bugs (Peck, ; Thompson & Carvalho, ), stink bugs (Gamberale‐Stille, Johansen, & Tullberg, ; Krall, Bartelt, Lewis, & Whitman, ), milkweed bugs (Skow & Jakob, ), harlequin bugs (Fabricant, Exnerova, Jezova, & Stys, ), and firebugs (Exnerova et al, )). While we have evidence of Habronattus frequently feeding on green leafhoppers in the field, we have never observed them feeding on species with bright colour patterns (pers.…”

“…If separate prey populations face selection pressures from predators with different colour biases, this may drive rapid divergence in prey colour patterns. Such a scenario may explain previously unresolved geographic variation in prey colouration (Fabricant & Herberstein, ; Lozier, Jackson, Dillon, & Strange, ; Ritland, ; Thompson & Carvalho, ).…”