Plant oviposition preferences in a generalist herbivore: Tests of host plant selection and the Hopkins’ host selection principle

Why and how herbivorous insects choose to feed on some plant species and
not others can be influenced by many factors, including an insect’s
physiological state, individual preferences, or the abundance of the host
plants in the environment. Yet, it is not always clear why herbivorous
insect species will choose to lay their eggs on some plants over others.
The Hopkins’ host selection principle (hereafter HHSP) hypothesizes that
female insects prefer to lay eggs on host plants upon which they fed as
larvae, but there are studies that both support and refute the hypothesis.
Here, we test HHSP in a dietary generalist moth, fall webworm (Hyphantria
cunea, hereafter FW). Previously, local host plant abundance has been the
only factor found to determine FW host plant use; whether FW exhibit
individual host plant preferences is unknown. We tested for HHSP in FW by
conducting preference tests with females of the two FW morphotypes
(red-head and black-head), presenting females with the same four host
plants: their one natal host plant, two other potential host plants, and
one non-host plant for that morphotype that is a host plant for the other
morphotype. Overwhelmingly, females of both the red-head and black-head
morphotypes oviposited on a non-plant surface in the choice arena rather
than any plant (89% and 83%, respectively). When female FW did oviposit on
a plant, they did not oviposit on hosts more often than non-hosts. Of the
few FW females that oviposited on a host plant, neither morphotype showed
preference for their natal hosts and thus we found no support for HHSP.
Our results support previous findings that HHSP is not a driver of host
plant selection, suggesting that female FW are not selective in their
choice of host plants, which can facilitate generalism in this species.