ZOBODAT - www.zobodat.at Zoologisch-Botanische Datenbank/Zoological-Botanical Database Digitale Literatur/Digital Literature Zeitschrift/Journal: Denisia Jahr/Year: 2006 Band/Volume: 0019 Autor(en)/Author(s): Mitchell Paula Levin Artikel/Article: Polyphagy in True Bugs: A case study of Leptoglossus phyllopus (L.) (Hemiptera, Heteroptera, Coreidae) 1117-1134 © Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at Polyphagy in True Bugs: A case study of Leptoglossus phyllopus (L.) (Hemiptera, Heteroptera, Coreidae)1 P.L. MITCHELL Abstract: The polyphagous species Leptoglossus phyllopus (L.) was examined with respect to host plant preference, tissue feeding specificity, seasonal dispersal among host plants, and life history. Mark-recap- ture, census, and rearing experiments demonstrated that this species exhibits true polyphagy, in that in- dividual bugs feed on plants from more than one family. Developmental parameters such as growth and survivorship did not differ among plants from several families, but did vary significantly with quality of host (e.g., wild vs. cultivated). Stadium duration, however, varied among wild host plant species in la- boratory experiments. Specialization on reproductive plant parts, coupled with sequential polyphagy and dispersal among a variety of seasonal host plants, allows multiple generations per year. Modes of fee- ding and preferred target tissues among coreids are discussed. Key words: leaffooted bug, Leptoglossus phyllopus, polyphagy, stylet sheath, target tissue. Introduction spp.), for example, employ a macerate-and- flush process, whereas an osmotic pump For phytophagous insects with piercing- mechanism is associated with coreids (MILES sucking mouthparts, feeding selectivity op- & TAYLOR 1994). However, some pentato- erates on two levels: preferred target tissue mids and lygaeids shift between salivary and host plant species. Tissue preference is sheath formation and lacerate-and-flush considered to be a conservative evolution- feeding (MILES 1972). ary character (TONKYN & WHITCOMB 1987); for example, specialization on xylem, Preference for a particular plant devel- phloem, or parenchyma is characteristic of opmental stage or structure (e.g., growing subfamilies or families in Auchenorrhyncha shoots, buds, ripe seeds), may also be associ- (PORT 1978). Phytophagous Heteroptera ated with specific groups. Pyrrhocoroidea have been extensively analyzed with respect feed predominantly on mature seeds, tingids to several factors associated with target tis- prefer mature leaves, while phytophagous sue preference: mouthpart morphology, sali- mirids concentrate on flowers, buds, and vary chemistry, preference for plant parts or new foliage (SCHUH & SLATER 1995). In structures, and mode of feeding (MILES some cases, however, such trends only be- 1972; COBBEN 1978; MILES & TAYLOR 1994; come evident at the tribal or even generic HORI 2000). The enzyme components of level. SCHAEFER & MITCHELL (1983) noted heteropteran saliva are considered to be a that an affinity for vegetative or reproduc- family-level character (MILES, cited in HORI tive structures is characteristic of tribes 2000), although induction of proteolytic en- within the Coreidae. Among Australian zymes has been demonstrated in a zoophy- coreids, KUMAR (1966) recognized two dif- tophagous mirid (ZENG & COHEN 2001). ferent types of feeding – exclusive sap feed- The mode of feeding may also be associated ing is found in some genera whereas others with particular taxa. Mirids (e.g., Lygus feed on both sap and fruit. However, such Denisia 19, zugleich Kataloge 1Dedicated affectionately to Ernst Heiss, my delightful colleague on the Executive Committee of the International der OÖ. Landesmuseen Heteropterists’ Society and heteropterist extraordinaire. Neue Serie 50 (2006), 1117–1134 1117 © Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at diversity of feeding was considered by phytophagous groups, he proposed that sap- COBBEN (1978) to indicate a “phase of un- feeding originated from polyphagous seed- balanced equilibrium.“ feeding, with the former mode of feeding tending toward a more restricted host range Even fewer generalizations may be made (COBBEN 1978). In Hemiptera in general, regarding host-plant specificity. Curiously, tissue-feeding specialization has been associ- the question of diet breadth in Heteroptera ated with host plant specificity (BERNAYS & has not been explored with the intense fer- CHAPMAN 1993), but this observation is vor devoted to insect-plant interactions in based primarily on the British fauna, and is Lepidoptera, Orthoptera, and other orders biased toward Sternorrhyncha and Auchen- of chewing insects. COBBEN (1978) charac- terized the Tingidae as monophagous while orrhyncha. Clearly, more information on suggesting that “polyphagy prevails“ among polyphagy in Heteroptera is needed. the phytophagous Miridae; but he provided The objective of this research was to no comparable analysis for the Pentatomo- conduct a detailed study of polyphagous morpha. Nearly 30 years have passed since feeding behavior in a single coreid species, the publication of COBBEN’s (1978) monu- the leaffooted bug Leptoglossus phyllopus mental study of mouthparts and feeding (L.). Host range and dispersal, seasonal pat- strategies, but our understanding of het- terns of host plant use, preferred feeding eropteran-plant relationships remains limit- site, and target tissue were examined in or- ed. Neither facultative zoophagy nor the ex- der to characterize the factors influencing treme polyphagy associated with some het- host plant selection. Leptoglossus phyllopus eropterans is properly understood (ZENG & damages legumes, tomatoes, tree nuts, and COHEN 2001). WHEELER (2001) observes citrus in the southern and eastern United that despite an extensive literature on crop States (MITCHELL 2000), and is considered a injury, there are “large gaps in our knowl- minor economic pest. The primarily edge of mirid-plant interactions.“ Informa- Neotropical genus Leptoglossus GUERIN was tion for some heteropteran groups is lacking, selected for study because it includes species detailed ecological studies of bugs outside of exhibiting widely disparate feeding strate- agroecosystems are uncommon, and adult gies ranging from strict monophagy to ex- host plant records are not always reliable in- treme polyphagy, as well as a number of dicators of breeding hosts (SCHAEFER & species of economic importance. Several MITCHELL 1983). Leptoglossus species are presently expanding Polyphagy in Heteroptera is of great in- their ranges – and potential for economic terest from both an economic and an evolu- damage – geographically. The highly tionary standpoint. Many of the major agri- polyphagous L. zonatus (DALLAS), a pest of cultural pests (e.g., Nezara viridula (L.), Rip- many crops in Mexico and South America, tortus clavatus (THUNBERG), Leptoglossus has recently invaded the southeastern Unit- zonatus (DALLAS), Lygus lineolaris (PALISOT ed States to Florida (BUSS et al. 2005) and DE BEAUVOIS)) have a wide range of host has become a pest of Satsuma oranges in plants (SCHAEFER & PANIZZI 2000). Howev- Louisiana, displacing L. phyllopus (HENNE et er, it is important to distinguish between al. 2003). Leptoglossus occidentalis HEIDE- generalist species composed of more special- MANN, once restricted to conifers in western ized populations and polyphagy at the indi- North America, has spread rapidly eastward vidual level (i.e., diet mixing) (FOX & MOR- across the continent to Ontario and New ROW 1981; BERNAYS & MINKENBERG 1997). England (RIDGE-O’CONNOR 2001). Acci- The evolution of omnivory has been shown dentally introduced into Italy in 1999 (TAY- to correlate with polyphagy in Heteroptera LOR et al. 2001), this species has now spread (EUBANKS et al. 2003), and these authors to Central Europe (RABITSCH & HEISS proposed that polyphagous, seed-feeding 2005). Thus, information on the feeding be- herbivores may be more likely to expand the havior of L. phyllopus may be applicable not diet to consume animal prey. COBBEN (1978, only in the southeastern United States, but 1979) considered polyphagous carnivory to to congeneric species of economic impor- be plesiomorphic within Heteroptera. For tance elsewhere. 1118 © Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at Materials and Methods Both L. phyllopus and another coreid, Eu- thochtha galeator (F.), were monitored. Num- Study site: Research was conducted pri- ber of adults, nymphs of all instars, and cop- marily at Brackenridge Field Laboratory ulations were counted. Location of bugs on (BFL), operated by The University of Texas the plant was noted in greater detail than in at Austin. This field station is located inside earlier censuses, differentiating between the city limits of Austin, Texas, along the bud, stem, and leaf primordia as well as be- shores of the Colorado River, and comprises tween mature plant organs. The 1979 cen- 32 hectares of grassland, cedar-post oak sus covered the entire reproductive life span scrub and semi-deciduous woodland. of the host plant Cirsium texanum BUCKL., Four study plots, each measuring 92.9 from bolting through seed set. 2 m , were established at BFL to investigate A plant census was conducted monthly seasonal activity of L. phyllopus and other in each study site in conjunction with the coreids. All plots were located in either ear- bug censuses in 1977 and 1978. Each plot ly successional or cultivated garden areas. was subdivided