Mating strategies in solitary aphid parasitoids: Effect of patch residence time and ant attendance

Abstract:
Mate finding and dispersal from the natal patch in parasitoid Hymenoptera

are influenced by the availability of host resources and interactions with other

organisms. We compared the mating behavior of three solitary aphid parasitoids,

Aphidius ervi Haliday, Lysiphlebus hirticornis Mackauer and Pauesia pini (Haliday)

(Hymenoptera: Braconidae: Aphidiinae) that differ in host resource exploitation and

ant mutualism. In L. hirticornis, which is obligately ant-attended, the residence time

on the natal patch was approximately 4 h compared with less than 2 h in the

facultatively ant-attended P. pini; the sexes did not differ in residence time. Females

of A. ervi, which is not attended by ants, stayed for slightly more than 2 h on the

natal patch while their male siblings remained for only 1 h. In L. hirticornis, 90% of

all siblings in a clutch mated on the natal patch but only 13% in A. ervi and 42% in P.

pini did so. Off-patch matings (23%) were observed only in A. ervi. Males and

females of L. hirticornis were 12-times more likely to mate on the natal patch when

aphids and ants were present than when either of the latter species was removed; and

patch residence time declined from approximately 4 h to approximately 2.5 h in the

absence of either aphids or ants. We propose that, in aphidiine wasps and perhaps

other quasigregarious parasitoids, mating behavior is influenced by the availability

of resources on the natal patch and the presence or absence of trophobiotic ants