Galls induced by Calophya latiforceps (Hemiptera: Calophyidae) reduce photosynthesis, chlorophyll and leaf growth of Brazilian peppertree saplings

Understanding how insect herbivores affect weed performance is essential to predict the outcomes of classical biological control programs. Because of its aggressive growth and absence of natural enemies, Brazilian peppertree is considered one of the worst upland weeds in Florida. Calophya latiforceps Burckhardt induces leaf galls on Brazilian peppertree; however, its effects on leaf perfomance and sapling growth are unknown. The objectives of this study were to measure the effect of gall formation on photosynthesis, chlorophyll and growth of leaves. Photosynthesis was measured on 8-month-old saplings with and without C. latiforceps. In plants infested with insects, leaves with galls had 2.2, 2.7 and 4.1-times lower photosynthesis compared to leaves without galls after 15, 30 and 45 d of nymph settling, respectively. To measure the impact of gall formation on leaf chlorophyll and leaf area, we followed performance of plants with and without C. latiforceps under greenhouse conditions. We haphazardly tagged three young leaves per plant and followed their performance over a 70 d period. After 15 d, the chlorophyll content of leaves with galls was on average 1.1-times lower compared to leaves without galls. After 69 d, the change in leaf area of leaves with and without galls was 92.0 ± 11.0 and 130.8 ± 6.0 cm², respectively. This indicates that folding and shedding of leaves with galls was responsible for a loss of 30% in leaf area compared to non-galled leaves. Our results demonstrated that damage by C. latiforceps reduces leaf performance of Brazilian peppertree. Under field conditions, high densities of galls are likely to have a negative impact on branch growth and eventually reproductive output.