Fitness costs and oviposition choice of C. nenuphar on blueberry and peach

In phytophagous insects, adult attraction and oviposition preference for a
host plant is often positively correlated with their immature performance;
however, little is known how this preference-performance relationship
changes within insect populations utilizing different host plants. Here,
we investigated differences in the preference and performance of two
populations of a native North American frugivorous insect pest, the plum
curculio (Conotrachelus nenuphar) ‒ one that utilizes peaches and another
that utilizes blueberries as hosts ‒ in the Mid-Atlantic United States.
For this, we collected C. nenuphar adult populations from peach and
blueberry farms and found that they exhibited a clear preference for the
odors of, as well as an ovipositional preference for, the hosts they were
collected from, laying 67-83% of their eggs in their respective natal
hosts. To measure C. nenuphar larval performance, a fitness index was
calculated using data on larval weights, development, and survival rate
from egg to fourth instars when reared on the parent’s natal and novel
hosts. Larvae of C. nenuphar adults collected from peach had high fitness
on peach but low fitness when reared on blueberry. In contrast, larvae
from C. nenuphar adults collected in blueberry had high fitness regardless
of the host they were reared on. In this study, we show that utilizing a
novel host such as blueberry incurs a fitness cost for C. nenuphar from
peaches, but this cost was not observed for C. nenuphar from blueberries,
indicating that the preference-performance relationship depends on the
particular insect population-host plant association.