Notes on the mating system of Hylesinus varius (F.)(Col., Scolytidae), a putatively bigynous bark beetle

Abstract

Previous research has left confusion about central features of the mating system of the common ash bark beetle Hylesinus varius; in particular, reports conflict as to whether this species is monogynous or bigynous. It was found that females initiated egg tunnel construction; copulation takes place either on the bark in the initial phase of egg tunnel construction, or inside the tunnel system. Observations of one male copulating with several females and of solitary females in galleries with eggs suggested that the males sometimes leave after copulation. In contrast to findings for populations in Slovakia, Norwegian male H. varius were most commonly paired with only one female. Bigynous galleries contained significantly more eggs than monogynous galleries, but bigynous males did not double their reproductive success as found in some other bigynous bark beetles. This suggests that bigynous galleries at first are the work of one female but some males are later joined by a second female.

Contribution to bionomy of Hylesinus fraxini (Coleoptera: Curculionidae: Scolytinae) and its monogamy in the Czech Republic

“…In the case of H. fraxini, suitable host trees are infested first by females, which immediately begin creating entry holes and a system of galleries for eggs (Loyning & Kirkendall 1999). To attract males, females produce primary attractants (Lieutier et al 2004).…”

“…To attract males, females produce primary attractants (Lieutier et al 2004). While constructing maternal galleries, mating occurs on the bark or inside the gallery system (Loyning & Kirkendall 1999).…”

“…The species is stated as being monogamous in Germany, Spain, France, and England. In Norway, bigamy occurred only in rare cases (in 4 out of 114 gallery systems) (Loyning & Kirkendall 1999). Assuming that H. fraxini was a bigamous species, each female would inhabit one of the gallery system's two branches (Rudinsky & Vallo 2009).…”

“…The scientific literature contains a number of conflicting opinions as to the bionomics of H. fraxini. Inconsistencies in the data mainly concern questions about the number of females in gallery systems (Loyning & Kirkendall 1999;Rudinsky & Vallo 2009; and the number of generations per season (Procházka 2009;Křístek & Urban 2013). Knowledge of these characteristics is important for forest managers to prepare timely and effective preventive and protective measures against this pest, and particularly to determine the number of trap tree series.…”