Journal of Asia-Pacific Entomology 17 (2014) 151–154 Contents lists available at ScienceDirect Journal of Asia-Pacific Entomology journal homepage: www.elsevier.com/locate/jape Short Communication The number of cecidomyiid insect galls affects the photosynthesis of Machilus thunbergii host leaves☆ Meng-Yuan Huang a, Hsueh-Mei Chou b, Yung-Ta Chang c,⁎⁎, Chi-Ming Yang a,⁎ a Biodiversity Research Center, Academia Sinica, Nankang, Taipei 115, Taiwan b Department of Biotechnology, Yuanpei University, HsinChu 300, Taiwan c Department of Life Science, National Taiwan Normal University, Taipei 116, Taiwan article info abstract Article history: Previous studies of the impacts of galls on host leaf photosynthesis do not suggest any general trends, with a re- Received 21 July 2013 ported range of effects from negative to positive. In this study, photosynthetic characteristics such as chlorophyll Revised 21 November 2013 fluorescence (Fv/Fm), photosynthetic capacity, and stomata conductance were determined in two types of fruit- Accepted 2 December 2013 like galls (red ovoid and green obovate galls) induced by Daphnephila taiwanensis and Daphnephila sueyenae,re- spectively, in order to investigate whether the number of galls affects the photosynthesis of galled leaves of Keywords: Machilus thunbergii. In 2008, chlorophyll fluorescence and photosynthetic capacity were negatively correlated Gall number fi fi Host leaf with gall numbers, non-signi cantly and signi cantly, respectively, whereas stomata conductance was positively Photosynthetic capacity but non-significantly correlated with gall numbers. In 2009, photosynthesis capacity and stomata conductance Stomata conductance were negatively, but non-significantly, correlated with gall numbers. Results imply that photosynthesis in M. thunbergii leaves is slightly affected by the number of cecidomyiid insect galls, and that the higher the gall num- ber, the greater the negative effect that galls have on host leaf photosynthesis and subsequent infection. © 2013 The Authors. Published by Elsevier B.V. on behalf of Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society. All rights reserved. Introduction Tokuda et al. 2008). Among them, both ovoid and obovate types of galls were assessed in the present study. Ovoid galls are induced by Insect-induced galls are an atypical growth and differentiation form of Daphnephila taiwanensis. Obovate galls are induced by Daphnephila plant tissue. Gall inducers use these new structures as shelters for protec- sueyenae (Tokuda et al. 2008). According to our field observations, tion and sources of nutrition. Galls cause multiple physiological changes larvae hatch from eggs in the spring, mine directly into leaf tissue, and in host plants such as changes in pH and polarity, excess sugars and free stay undeveloped until fall. Galls then begin to develop around October amino acids, alterations in nutrient composition, deficiencies in pig- and mature soon thereafter. Larvae develop into the second and third ment–protein complexes, lower chlorophyll and carotenoid content, instars in mature galls and emerge in the early spring of the following and a higher content of secondary metabolites, all of which may impact year (Huang et al. 2009). the photosynthetic capacity of host leaves (Stone and Schönrogge, Previous studies on the impacts on host leaf photosynthesis by gall- 2003; Yang et al., 2003, 2007; Motta et al., 2005; Huang et al., 2009, 2011). formers do not suggest any general trends, which have been reported to Machilus thunbergii is an abundant and common subtropical tree have a range of effects from negative to positive (Yang et al., 2003). No species that is widely distributed in Asia. It is located 200–2000 m confirmation of this has been published in the past ten years, leaving the above sea level (asl) in Taiwan, and can grow to 18–20 m tall with pro- issue unresolved. fuse branching (Wu et al. 2006). Gall midges of the Cecidomyiidae are a Regardless of whether net photosynthesis is directly measured in major group of gall inducers, and most of them are highly host-specific. galls or estimated from radioactive labeling experiments, the photosyn- In Taiwan, five of eleven gall types found in Machilus, are induced by thetic rates of galls are usually much lower than in normal leaf tissues Daphnephila midges and are considered new species (Yang et al. 2002, (Dorchin et al., 2006). A lower photosystem (PS) II efficiency, as deter- mined by chlorophyll fluorescence (Fv/Fm), was found in Cecidomyia ☆ This is an open-access article distributed under the terms of the Creative Commons midge galls on Carya glabra leaves, Cynipid wasp galls on Quercus Attribution-NonCommercial-No Derivative Works License, which permits non- velutina leaves, and Eriophyidae mite galls on Ulmus alata leaves com- commercial use, distribution, and reproduction in any medium, provided the original au- pared to uninfected tissues of those leaf surfaces (Aldea et al., 2006). thor and source are credited. The photosynthetic rates of galled leaves as measured by gas ex- ⁎ Corresponding author. Tel.: +886 2 27871095; fax: +886 2 23142234. change were reduced in comparison to ungalled leaves on naturally ⁎⁎ Corresponding author. Tel.: +886 2 77346288; fax: +886 2 29312904. E-mail addresses: [email protected] (H.-M. Chou), [email protected] growing Prunus serotina and Rhus glabra (Larson, 1998). Water poten- (C.-M. Yang). tial, photosynthetic rate (indicated by gas exchange), transpiration, 1226-8615/$ – see front matter © 2013 The Authors. Published by Elsevier B.V. on behalf of Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society. All rights reserved. http://dx.doi.org/10.1016/j.aspen.2013.12.002 152 M.-Y. Huang et al. / Journal of Asia-Pacific Entomology 17 (2014) 151–154 and stomata conductance of host leaves were decreased when Epiblema Photosynthetic capacity and Fv/Fm strenuana galls were found on Parthenium hysterophorus (Florentine et al., 2005). Photosynthetic capacity was measured at saturating light intensi- In contrast to the above, Acacia pycnantha phyllodes hosting ties under 800 μmol m−2 s−1 photosynthetic photon flux density wasp-induced galls had higher photosynthetic rates than similarly- (PPFD) at ambient temperature. All measurements were taken be- aged phyllodes without galls, as indicated by gas exchange experi- fore 11:00 a.m. to avoid the midday depression in photosynthesis. ments (Dorchin et al., 2006). Photosynthesis (indicated by gas Chlorophyll fluorescence was detected at dawn on dark-adapted exchange), stomata conductance, and water potential were also galls for 20 min with leaf clips and uninfected tissues of the same leaf at increased on Silphium integrifolium leaves hosting Antistrophus ambient temperature with a Pocket Plant Efficiency Analyzer (Hansatech, silphii galls in comparison to ungalled shoots (Fay et al., 1996). U.K.). The maximum quantum efficiency of PSII (Fv/Fm) was calculated Scale insects on the leaves of Ilex aquifolium can also cause higher from (Fm − Fo) / Fm, where Fo, Fm, and Fv are background fluorescence, PSΙΙ energy transduction efficiencies in affected than uninfected tis- maximum dark-adapted fluorescence, and maximum variable fluores- sues, as indicated by chlorophyll fluorescence (Fv/Fm) (Retuerto cence, respectively (Weng et al., 2006). In our 2008 study, 93 leaves et al., 2004). with varying numbers of galls (0–26) were assessed for chlorophyll Additionally, several other studies suggest that no general trends fluorescence as presented by Fv/Fm. have been found in the impacts of gall-formers on host leaf photosyn- thesis (Andersen and Mizell, 1987; Fay et al., 1993; Bagatto et al., Statistical analysis 1996). Apparently, the way that insect-induced galls affect the photo- synthesis of galled and ungalled leaves is interesting and still under dis- Differences in photosynthetic parameters among tissues were ex- pute. In this study, therefore, we determined several photosynthetic amined using a completely randomized analysis of variance. The rela- characteristics of host leaves galled with various numbers of galls. tionships between parameters were examined using simple linear regression models. All statistical analyses were conducted using JMP software, version 5.01 (SAS Institute; Cary, NC). Materials and method Plant and galls Results and discussion Red ovoid galls induced by D. taiwanensis and green obovate galls in- We previously studied Fv/Fm and PSII values in three types of leaves duced by D. sueyenae were obtained from the Yangmingshan National on M. thunbergii. These were galled (GL) and gall-free leaves (GS) on Park located in the north-western part of Taipei, Taiwan. The healthy galled shoots, and gall-free leaves on gall-free shoots (FS). Fv/Fm values portions of galled leaves hosting various numbers of galls on Machilus in these three types were significantly higher than in green obovate- thunbergii trees in the field were used for the study (Fig. 1). We sampled and red ovoid-shaped galls, and no significant differences in Fv/Fm trees for each of the two types of galls and also collected data from gall- were observed among GL, GS, and FS leaves. These results suggest that infected leaf from each set in the early springs of 2008 and 2009, when PSII efficiency in galled and ungalled leaves of M. thunbergii may not the galls were mature. Leaves with one species and two species of gall be affected by galling (data not show). In our study, most (82/93) of insects were randomly chosen for measurements. the Fv/Fm values were between 0.75 and 0.80, which is normal based AB C Fig. 1. The morphology of green obovate and red ovoid galls residing on Machilus thunbergii host leaves. Pictures were taken in the lab. A and C, M. thunbergii leaf infested by only obovate- or ovoid-shaped galls, respectively; B, M. thunbergii leaf on which both galls were induced. Scale bar: 4 cm. M.-Y. Huang et al. / Journal of Asia-Pacific Entomology 17 (2014) 151–154 153 0.85 Photosynthetic capacity has negative and significant relationships with gall numbers for the 2008 and negative and non-significant for the 2009.