Effects of sex and age of a dioecious tree, Forchhammeria pallida (Capparaceae) on the performance of its primary herbivore, Murgantia varicolor (Hemiptera: Pentatomidae)

The effects of sex and age of a dioecious tree, Forchhammeria pallida, on the survival and development of a Mexican harlequin bug, Murgantia varicolor, were examined. In the laboratory, bugs reared on fruits or fruits and leaves developed rapidly and had a high rate of survivorship, whereas bugs reared on leaves alone developed slowly after the second instar and died by the fifth instar. Murgantia varicolor showed a preference for leaves from juvenile plants over leaves from mature plants, and bugs reared on leaves from juvenile plants survived significantly longer than those reared on leaves from mature plants. Murgantia varicolor showed no preference for feeding on leaves of mature male versus mature female plants. In the field, M.varicolor occurred on male, female and juvenile plants. Although nymphs were less common on male than female F.pallida, their presence in substantial numbers shows that M.varicolor oviposits on both male and female plants. However, adult M.varicolor were rare on male plants. This result is supported by the inability of nymphs to complete their development on vegetative parts of F.pallida in the laboratory. These observations suggest that dioecy in F.pallida may be disruptive to populations of M.varicolor.