Factors underlying the late seasonal appearance of the lepidopterous leaf‐mining guild on oak

Abstract

Abstract. 1. Most lepidopterous leaf mining species found on the oak Quercus robur in Britain develop in summer. At this time of year, externally feeding caterpillars remove little leaf area since most of these free living folivores are predominantly spring feeders. 2. I forced Phyllonorycter harrisella (L.) miners to oviposit in spring, then exposed developing larvae to a wide range of leaf damage levels. 3. Leaf miner survivorship and mean female pupal weight were significantly greater in the experimental spring generation on undamaged oak leaves, this being when oak foliage is of the highest nutritional quality. 4. Leaf miner survivorship in all generations is correlated with natural leaf damage levels. Experimental leaf damage also reduces miner survivorship. 5. Leaf damage reduces miner survivorship by increasing the probability of larval death due to wound induced responses. 6. The role of asymmetrical competitive interactions between caterpillars and leaf‐miners in determining the late seasonal appearance of miners is discussed. It is suggested that wound induced responses may play an important part in the structuring of phytophagous insect communities.