Observational Notes on Short-Lived and Infrequent Behaviors Displayed by Reticulitermes ﬂavipes (Isoptera: Rhinotermitidae)

BEHAVIOR Observational Notes on Short-Lived and Infrequent Behaviors Displayed by Reticulitermes ﬂavipes (Isoptera: Rhinotermitidae)

1 J. G. WHITMAN AND B. T. FORSCHLER

413 Biological Science Building, UGA, 120 Cedar Street, The University of Georgia, Athens, GA 30602

Ann. Entomol. Soc. Am. 100(5): 763Ð771 (2007) ABSTRACT Behaviors displayed by worker termites, which make up 80Ð90% of any eastern subterranean termite population, provide the foundation for understanding the details of termite social organization. Individually marked termite workers were placed in an enclosed, darkened arena and videotaped for three 24-h periods. Behaviors observed in detail include ecdysial assistance, gallery excavation, oscillatory movements, worker feeding and adult mating. Primary reproductive pairs were observed to mate, on average, once every 3 d. Ecdysis lasted 43 min and involved multiple allogrooming attendants. Excavating termites manipulated the substrate with their mouthparts and showed Þdelity to the site of excavation but not the site of deposition. Four different types of oscillatory movements were characterized with the type IV always ending in defecation. Worker feeding behaviors are described that involve swallowing materials obtained by Þve different routes and evoke use of the superorganism concept. The relevance of these observations for a better understanding of a variety of topics, including biology, management, and evolution of these economic pests, is included.

KEY WORDS subterranean termite, worker behavior, feeding, social interactions, allogrooming

Our understanding of termite biology is impaired by Materials and Methods conundrums that would beneÞt from detailed descrip- Detailed descriptions of the arena and experimental tions of various behaviors (Thorne et al. 1999, Laine design can be found in Whitman (2006). Marked ter- and Wright 2003). The majority of published reports were conducted by visual observations made in real mites were videotaped in three-chambered, glass- time. Descriptive accounts of short-lived or infrequent topped, artiÞcial arenas made of Densite. The narrow behaviors, taken as they occur, are complicated by rapid conÞnes of a termite gallery were simulated by an movement or frequency of occurrence. Reviewing Þlm arena depth of 2 mm. The three chambers, each mea- has several advantages, including the opportunity to suring 2.3 by 3 cm, were connected by 3-mm-wide score events at a later time, detailed examination of openings in the 1-mm-thick walls that deÞned separate ␣ short-term or rapid movements, and simultaneous scor- chambers. Chambers were half-Þlled with -cellulose ing of multiple subjects. Examples of Þlming in the lit- powder and kaolin clay as feeding and tunneling sub- erature include several studies of termopsid vibratory strates, respectively. Three Jai coefÞcient of variation- behavior (Howse 1962, 1965; Stuart 1988) and one each M50IR charge-coupled cameras, two equipped with on kalotermitid group interactions (Maistrello and Navitar 7000 zoom lenses and one with a 35-mm tele- Sbrenna 1996), Coptotermes delate behavior (Raina et al. photo zoom lens, were placed above the arena to 2003), and feeding of Coptotermes, Reticulitermes, and record termite behaviors with one camera per cham- Incisitermes (Indrayani et al. 2007). ber. Recordings used two Panasonic AG-2560 SVHS We recently concluded an experiment that re- and one Emerson DA-4 Head brand VCR. AEC Box-18 quired reviewing Ͼ400 h of videotape of Reticuli- video time-code generators allowed precise determi- termes ﬂavipes Kollar (Isoptera: Rhinotermitidae) that nation of behavioral start and stop times. The VCRÕs yielded several interesting qualitative observations. In “extended play” mode enabled8hofcontinuous re- this article, we describe Þve behaviors not previously cording but resulted in a loss of video quality. The discussed in detail such as mating between 18-mo-old movement of small body parts such as the maxillae and kings and queens, ecdysis in the worker caste, “tail- maxillary palps were obscured, but there was sufÞ- chasing,” feeding, and excavation. In addition, we pro- cient clarity to observe movements of the body, an- Þle four types of oscillatory movements (OM) and tennae, and mandibles. conclude with a discussion of the implications of these Six arenas were Þlmed involving two treatments, observations. laboratory colonies that were 18-mo-old and equal- sized groups of workers randomly selected from Þeld- 1 Corresponding author, e-mail: [email protected]. collected populations. The six replicates, containing

0013-8746/07/0763Ð0771$04.00/0 ᭧ 2007 Entomological Society of America 764 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 100, no. 5

Ϸ50 termites per arena, were Þlmed for 24 consecutive lose powder. It was assumed that the maxillary and hours on three separate days: days 1, 4, and 7 after labial palps performed the bulk of shaping the mac- placement in the arena. The behaviors described in- erated substrate, into a pill, by pressing against the cluded a review of all 432 h of video on fast-forward labrum. to catch the mating, tail-chasing, and ecdysial events Pill formation was initiated by a lateral extension of reported. Feeding, OMs, and excavation behaviors the mandibles followed by forward movement of the were scored on six workers per replicate for 12 evenly body (tarsi remaining stationary) that pushed the spaced 15-min intervals over the course of a 24-h day, head capsule into, as the mandibles closed and cut, totaling 3 h per worker per d to obtain the frequency the substrate simultaneous with alternating rotations and time-spent data. (describing a 45Њ arc) of the head capsule. The overall Glossary of Behavioral Terms. In the interest of dis- impression was that the substrate was “shoveled” into cussion, we provide a glossary of terms, listed alpha- the mouthparts. This distinctive head motion, de- betically, used in the behavioral descriptions. Video scribed by Stuart (1967) as “a characteristic side-to- Þles of selected behaviors can be viewed and down- side motion of the head” and “pulling activity” by loaded at http://www.ent.uga.edu/termitebehavior. Indriyani et al. (2007), was observed in both pill for- htm. mation and deposition. Pill formation was accompa- Allogrooming is deÞned as grooming of one individ- nied by a barely discernible rocking motion of the ual by another in contrast to self- or autogrooming. entire body as the head capsule was pushed into and Allogrooming was characterized by rhythmic lateral pulled away from the substrate. The movements de- movements of the mandibles while the head capsule scribed for pill formation were displayed by termites remained in contact with various body parts (i.e., the obtaining a bolus of cellulose from the arena but was head, antenna, legs, thorax, and abdomen) of another differentiated from excavation by chewing and con- termite. This type of grooming did not physically dis- sumptionÑin successionÑto encompass the act of place the subject being groomed. autofeeding cellulose. Pill formation is analogous to Chewing behavior was described by movement of the three “activities” describing as “feeding behavior” the mouthparts indicative of macerating a substrate in Indrayani et al. (2007). before ingestion. Chewing was characterized by Pill deposition was characterized by repeated, al- rhythmic lateral movement of the mandibles. The sub- ternating head capsule rotations combined with a strate being chewed was often clearly visible as it was backward movement of the body mimicking pill for- manipulated by the mouthparts before consumption. mation in reverse. Pill transportation and deposition Consumption was deÞned by cessation of chewing were readily distinguished from chewing by the ab- with no visible signs of having donated or deposited sence of mandibular movement and characterized by the macerated material. We divided consumption into the mandibles being held in an extended or open two classes (autofeeding and allofeeding) based on posture. how the food was acquired. Trophallaxis, as described Pumping is indicative of the hydrostatic swelling of by Wheeler in 1918 (Sleigh 2002) and applied in later the body during ecdysis before rupture of the ecdysal studies by Wilson (1975), is an exchange of food and suture (Chapman 1998). In termite workers, pumping information that could be either stomodeal (by was characterized by peristaltic-like contractions of mouth-to-mouth contact) or proctodeal (by mouth- the body that started at the tip of the abdomen and to-anus contact). Trophallaxis and feeding on wood progressed to the thorax. was found to be inadequate to describe the distribu- Tail-chasing is a behavior characterized by two tion of behaviors we term “consumption” by worker workers chasing the tip of each otherÕs abdomen re- termites. Materials that were procured through some sulting in tracing circles with their movement. action by the consumer are termed Autofeeding events Vigorous allogrooming was strong enough to phys- and included ␣-cellulose obtained from the arena ically displace or move the subject being groomed, (autofeeding cellulose, assumed analogous to feeding often for a distance of several body lengths. on wood); a bolus formed during the act of allogrooming (autofeeding allogrooming); and a clear, viscous bolus formed after regurgitation (autofeeding regur- Results and Discussion gitation). Allofeeding was deÞned by consumption of a donation from the anus of a nestmate (allofeeding Mating. Three mating events were observed in 18- proctodeal) or the mouth (allofeeding stomodeal). mo-old R. flavipes laboratory cultures that contained Excavation was the act of extending a gallery primary reproductives, soldiers, larvae, and workers. through one of the two substrates provided (kaolin Eggs were not present in any replicate throughout the clay or cellulose powder) and was accomplished in experiment. Reproductives from one culture mated four distinct phases: pill formation, pill transportation, twice, on day 1 and day 7, whereas one replicate pill deposition, and return to the excavation site. displayed one mating event, on day 7, and the third Pills were formed by a termite facing the active site pair never mated. The adult females were not physo- of excavation. Pills were “barrel-shaped” objects gastric; thus, we could not differentiate males and whose width and length were presumably established females with certainty. Mating events lasted 34Ð42 s by the size (width) of the mouthparts and were (mean duration, 38.7 Ϯ 4.2 s) and involved three formed, in our study, of either kaolin clay or ␣-cellu- phases: antennation, positioning, and coupling. Adult September 2007 WHITMAN AND FORSCHLER:SHORT-LIVED BEHAVIOR BY R. flavipes 765 behaviors were noted 20 min before and after each ers, soldiers and larvae but no eggs. Matings occurred mating episode. in our R. flavipes study once every 3 d, a Þgure that Mating events were determined to begin when one agrees with the conclusions of Costa-Leonardo and adult approached and rapidly antennated the otherÕs Patricio (2005) that spermatheca size speaks to mul- head capsule. This behavior was almost instanta- tiple matings. The variability of termite behavior is neously returned in kind. The rapid antennations by illustrated by the one reproductive pair we observed each adult started from the head and proceeded at to mate twice, a second pair mated once, and the third roughly equal speed to the tip of the abdomen. The was never observed to mate over 3 d. forward motion this required, combined with the fo- Tail-Chasing. We observed eight separate pairs of cus each had on the otherÕs abdomen, caused each workers performing a tail-chasing behavior similar to reproductive to describe a rough half-circle at which the “half-turn” described with adults during the rapid point antennation ceased. The head of the Þrst adult antennation phase of mating. Tail-chasing was initi- was adjacent to the abdominal tip of the second and ated by a worker that seemed to solicit a proctodeal vice versa ending the antennation phase which lasted exchange by antennation of the abdominal tip fol- 7Ð9 s (8.7 Ϯ 1.5 s). lowed by the intended donor turning and attempting The positioning phase followed as the adults to solicit the same by antennation. Workers would straightened their bodies and walked forward until the then describe full circles with the tandem movement tips of their abdomens were roughly parallel, and, with as each tried to maintain antennal or head capsule slight adjustments by both, brought their abdominal contact with the otherÕs abdominal tip. Chewing by tips together. The positioning phase lasted 3Ð8 s (5.0 Ϯ either participant was never observed after a tail- 2.6 s) and was followed by coupling, which was main- chasing episode. There was no rapid antennation, and tained for 22Ð30 s (25.0 Ϯ 4.4 s). Mating events ended tail-chasing did not end with an attempt to bring the with uncoupling and the adults, after walking a short abdominal tips together, indicating that this behavior distance, resumed what they had been doing earlierÑ was not a mimic of the mating half-rotation displayed standing still. by the adults. Tail-chasing events persisted longer Afzal (1985) studied mating in Ͼ300 reproductive (mean duration 413 Ϯ 201 s, range 157Ð725 s, n ϭ 8) pairs, established and recently paired, of the drywood and described numerous complete circles (each rev- termite Bifiditermes beesoni (Gardner). Afzal reported olution taking 9.6 Ϯ 1.7 s, range 8Ð12 s, n ϭ 8) com- a complex mating ritual involving antennation, head- pared with the single half-turn executed by the adults butting, allogrooming, and “abdominal quivering” during the antennation phase (mean duration 8.7 s, reminiscent of OMs, without providing durations. The range 7Ð10 s, n ϭ 3). mating episodes we observed did not involve any ob- Tail-chasing behavior has never been mentioned in vious preparation beyond the initial antennation. subterranean termites. We hypothesize this display is The pair that was observed to mate twice also per- the result of miscommunication of the signal to solicit formed several episodes of the antennation phaseÑas proctodeal material and suggests antennation of the had preceded the other mating eventsÑwithout pro- abdominal tip, alone, does not signal a request for ceeding to the positioning or coupling phases. There donation. The state of the donor should play a role in were three displays of rapid antennation behavior allofeeding proctodeal events and the rarity with observed on day 4 (successful matings were recorded which this behavior was observed would indicate mis- on day 1 and 7 with this pair), with 10 min elapsing communication. However, tail-chasing could simply between the Þrst and second episodes, whereas 30 min be a high-speed rehearsal for the adult mating half- passed between the second and third rapid antenna- turn. Unfortunately, we did not identify the sex of the tion displays. performers and so cannot provide support for the Raina et al. (2003) analyzed time-lapse video re- latter hypothesis. cordings and determined that Coptotermes formosanus Ecdysis. We witnessed two molting events during (Shiraki) reproductives (n ϭ 19 pairs) mated, on av- our experimental observations. The Þrst began around erage, 2.2 times in the 48-h immediately after ßight and 2:28 p.m. on day 7, lasted 43 min, and included three pairing. Raina et al. (2003) noted “extensive groom- phases: pumping, ecdysis, and recovery. The subject ing” between reproductives immediately before mat- began pumping with contractions increasing in inten- ing, a behavior we did not observe, and that C. for- sity and duration over 12 min. The ecdysis phase began mosanus“matings” lasting 27.9 Ϯ 7.8 s, which is close to with the cuticle splitting along the upper dorsal mid- the coupling phase (25.0 Ϯ 4.4 s), we recorded for R. line of the thorax as the not-yet sclerotized insect flavipes. C. formosanus laid eggs in batches over the emerged from the old cuticle. The time from suture course of weeks rather than daily (Raina et al. 2003). rupture to removal of the old cuticle took Ϸ10 min. It is clear from our9dofvideo that egg laying is not The recovery phase lasted 20 min and consisted of the a daily occurrence in R. flavipes as assumed by Grube transition from a near motionless state (there was and Forschler (2004) in their population growth periodic leg ßexing) in a side-laying recumbent posi- model. tion to the return to an upright posture and self- This is the Þrst detailed account of mating events in locomotion. R. flavipes. Undoubtedly, primary reproductives mate Pumping attracted the attention of a single nestmate shortly after ßight, as evidenced by the 18-mo-old that began allogrooming at 2:40 p.m., and this individ- laboratory cultures we Þlmed that consisted of work- ual continued allogrooming throughout the ecdysis 766 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 100, no. 5 event. The number of workers performing allogroom- pleting the molt through extracting the lower thorax ing varied over the course of the ecdysis as the subject and abdomen. The jack-knife position would occur as was continually allogroomed by as many as Þve nest- a notable event in bioassay as the result of no assis- mates at any given time. Termites involved in ecdysis- tance during molting and possibly indicating a signal allogrooming displayed various degrees of Þdelity, that the affected termite is “not normal.” ranging from 30 s to 5 min, and only one individual Excavation. Termites involved in excavation did not groomed throughout the entire event. The vigorous differentiate the food quality of the substrate. It should allogrooming observed during ecdysis displaced the be noted that termites involved in pill formation were subject over an area of 3 cm2. Allogrooming of a never observed consuming either substrate nor were nonecdysing worker never displaced the subject over termites observed to use a body part other than more than a body length. mouthparts during gallery construction. Gallery for- The exuvia was constantly attended, during and mation involved excavation in either ␣-cellulose pow- after the molt, by at least one termite that seemed to der or kaolin clay (n ϭ 136). Excavation was charac- be engaged in allogrooming. It was never evident that terized by three stages beginning with obtaining and any termite attempted to consume the exuvia during manipulating the substrate to form a pill (pill forma- ecdysis, but once it was completely removed the old tion), which was transported from the excavation site cuticle was torn apart and consumed by 16 different (pill transportation) and placed at another location termites over the next 28 min. The newly molted (pill deposition). Deposition of a pill was usually fol- subject solicited and procured a proctodeal allofeed- lowed by return to the excavation site to continue the ing 10 min after the recovery phase ended. task of gallery construction. During the course of the Þrst molting event, a sec- Excavation sites were often attended by more than ond termite undergoing ecdysis was dragged onscreen one termite. The width of a developing gallery allowed at 2:45 p.m. by vigorous allogrooming. At the time of a single termite to extend the gallery by pill formation, appearance, several terminal abdominal segments of which forced others intent on excavation to line up or the second subject still remained in the old cuticle. wait at points adjacent to the gallery entrance. The The second event proceeded as the Þrst, including the worker that was excavating would form a pill and back gradual decrease in allogroomers and consumption of out, at which point those waiting would push forward exuvia. Comparing the ecdysis timelines, the second in an attempt to gain access to the developing end of ecdysis seemed to have begun Ϸ3 min before the Þrst. the gallery. La Fage and Nutting (1978) state that consumption Pills, once formed, were immediately transferred of exuvia by termites is primarily an act of sanitation out of the developing gallery and placed along the with the secondary role of nitrogen recycling. Rosen- periphery of one of the chamber walls. A limited gaus and Traniello (1993), working with Zootermopsis, number of pills were deposited on the ßoor near the mention the act of nestmate assistance with molting, excavation site before return to the queue or to pill although their description does not detail the number formation at the excavation site. These “errant” pills involved or percentage of molting events that involved were later moved to the chamber walls, but it was not assistants. Su and Scheffrahn (1993) likewise mention, determined whether the same termite was involved in without elaboration, that molting is a group event. The the later movement. Chamber walls were lined with molting episodes we described are the Þrst detailed pills within the Þrst 24-h in Þve of the six replicates, description of ecdysis being an activity that attracts with the exception being a replicate where excavation the attention of up to 16 different workers. began between days 4 and 7. Group-assisted molting behavior has implications Individuals involved in excavation had several lo- for a diversity of topics such as toxicant transfer and cations where pills were deposited with no indication evolution of social behavior. The beneÞt of developing of site Þdelity. The route to and from the deposition a life history dependent on group-assisted growth site was often circuitous especially in chambers where (molting) would be to hold immatures to a social other termites obstructed a direct path. Return to the lifestyle analogous to the dependent larval stage of the excavation site was, on occasion, interrupted by a stop social Hymenoptera (Wilson 1971, Nalepa 1994, Shell- at another excavation site but the worker would al- man-Reeve 1997). The mechanisms used to explain ways leave this “secondary” site and return to the toxin transfer, for example, mention mortality during original to form a pill. Individuals were seen at differ- ecdysis (Su and Scheffrahn 1993, Sheets et al. 2000) ent excavation sites at different observation intervals, without considering the mechanism of group-assisted but they were never observed to excavate at more than molting. The “jack-knife” position of workers exposed one site during a particular 15-min scoring interval, to a chitin synthesis inhibitor described by Su and indicating a degree of excavation site Þdelity. Scheffrahn (1993) is analogous to the condition we The literature on termiticide efÞcacy has, for 20 yr observed at the beginning of the ecdysis phaseÑafter (Su and La Fage 1984), endeavored to account for the hydrostatic pumping and suture ruptureÑwhile the importance of behavioral reaction to soil treatments not-yet sclerotized termitesÕ upper thorax emerge but (Forschler 1993, Gold et al. 1996, Valles and Woodson the lower thorax, legs, and abdomen remain in the old 2002), but the details of the mechanics of excavation cuticle. We can speculate on a reason for Þnding have yet to be considered (Laine and Wright 2003). termites in this position in those bioassays assuming Recent studies on termite tunneling have focused on that allogrooming nestmates assist in ecdysis by com- the direction, distance, and angle without examining September 2007 WHITMAN AND FORSCHLER:SHORT-LIVED BEHAVIOR BY R. flavipes 767 the mechanism (Pitts-Singer and Forschler 2000, Cor- played as a single event did, on occasion, signal a nelius et al. 2002, Su and Puche 2003, Campora and nestmate to cease grooming or move aside. The type Grace 2004). Fifty years ago, Ebeling and Pence III OMs performed in succession induced no apparent (1957) reported that R. hesperus used the head and reaction from nestmates. It is worth noting that OMs body to compact sand while small particles were taken were never performed by termites waiting for another into the “buccal cavity” and mixed with a “gluey sub- to vacate an excavation site. stance” for placement along gallery walls, whereas Howse (1962) coined three terms to describe the larger particles were carried in the mandibles. The use distinctive jerking or jittery movements observed in of dried fecal pellets as building blocks and liquid feces termites. The Þrst, called vertical oscillatory move- as cement has been noted in Zootermopsis (Stuart ment (VOM), was described as a rapid up-and-down 1967, Howse 1968) and Macrotermes (Gerber et al. motion of the termite head capsule. The second, 1988). However, we observed none of these practices termed longitudinal oscillatory movement (LOM), in R. flavipes. Whether the differences indicate spe- was indicated by a back and forth motion of the entire cies-speciÞc repertoires or are merely artifacts of our body, whereas complex oscillatory movement (COM) experimental design will require further experimen- involved both vertical and horizontal body move- tation. It is clear from our study that gallery construc- ments. Oscillatory movements have been described tion through substrates with a small particle size is from numerous termite species and referred to as an linked to pill formation. Close examination of shelter “alarm reaction” (Howse 1962, 1964, 1965), as evoking tubes suggests that pills are the basic building blocks attraction (Stuart 1963, Reinhard et al. 1997, Reinhard of subterranean termite construction. We have ob- and Clement 2002), dispersal (Rosengaus et al. 1999a), served, in structural infestations, shelter tubes com- or eliciting building and repair activities (Stuart 1963, posed of pills of earth, polystyrene insulation, and 1967). The occurrence of OMs suggest this behavior gypsum several feet from the assumed source of those has purpose, yet the disparate associated activities materials. Understanding this aspect of termite behav- clearly indicates additional study is required to fully ior would shed light on the potential for movement of understand the reason or function of this behavior. toxicants using pill formation/construction behavior. We observed termites being groomed perform a Gallery construction involving extensive manipula- single type III OM at which point the grooming ter- tion of the substrate using mouthparts would certainly mite immediately ceased. Additionally, termites mov- play a role in understanding transfer of substrate- ing through an arena were observed to perform a borne termiticides. Our data indicates that 50% of the single type III OM if their path was blocked by a time spent during gallery construction (pill formation, nestmate, which typically resulted in the obstructing transportation, deposition, and return to the excava- termite moving to create a clear path. This observation tion site; n ϭ 136) involves contact with a pill, exposing agrees with a point by Maistrello and Sbrenna (1996) excavating termites to an oral dose of toxicant. that Kalotermes performing OMs are responding to a Oscillatory Movements. We recorded four dis- short-term need rather than an alarming stimulus. tinctly different OMs but because of the overhead Linking the type IV OM with defecation is the Þrst view it was difÞcult to determine any vertical com- substantive (100%; n ϭ 85) connection between an ponent. An OM was described by longitudinal oscil- OM display and a resultant behavior. The type IVs lations that moved approximately one-quarter of a slow, rhythmic mimic of the rapid type I-III OMs body length in alternating forward and backward allows comparison to the longitudinal body move- movements that began with a clearly deÞned forward ments involved in pill formation. We hypothesize that lunge. The termiteÕs tarsi remained stationary on the the rocking motion that accompanies extraction of a substrate while its body was in motion. OMs, from our mouthful of substrate during pill formation, also de- observations, involved the same movements but were scribed by Indriyani et al. (2007) for three species differentiated by speed, duration, and repetition. feeding on wood, are one and the same and the genesis The type I OM was brief, lasting Ϸ0.5 s from the Þrst of the movements involved in OMs. oscillation to the last, with the rapid motion blurring Feeding Behavior. Observations on the mechanics the video-taped image (n ϭ 390). The type II OM was and distribution of feeding behaviors can provide in- much slower taking Ϸ2 s to complete (n ϭ 140). The sights into the digestive physiology of subterranean type III OM type involved a type I followed immedi- termites. There were Þve routes by which the workers ately by a type II (n ϭ 269). The type III OM was often in our study consumed something: autofeeding cellu- performed three times or more in succession. The type lose (n ϭ 311), autofeeding regurgitated (n ϭ 198), IV OM was Ϸ3 s in duration and contained the slowest autofeeding allogrooming (n ϭ 146), allofeeding sto- oscillations with each movement clearly visible on modeal (n ϭ 246) and allofeeding proctodeal (n ϭ video (n ϭ 85). 336). The nutritional value of each material was not The type IV OM was associated with defecation. examined but can be inferred based on the source of Type IV OMs always immediately preceded deposi- the material. tion of visible frass. Assigning clear associations to any Autofeeding cellulose was assumed to be analogous of the other OMs was difÞcult, because we did not to termites feeding on wood and was the only source detect an apparent precursorÑbehavior or inci- of unaltered cellulose we observed to be consumed by dentÑthat triggered an OM, nor could we assign a the worker caste. Three routes involved partially di- consistent nestmate response. The type III OM dis- gested materialsÑautofeeding regurigated and both 768 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 100, no. 5 allofeedings. Autofeeding allogrooming (n ϭ 146 of the donorÕs behavior did not change (i.e., it was chew- 2,983 allogrooming events) has never been reported as ing when the event began). However, the literature a feeding behavior, and the food quality of this ma- often does not differentiate, in experiment design, terial should be examined in future research. Termites between stomodeal and proctodeal trophallaxis and autofeeding allogrooming were never solicited for a usually assume a one-way transfer (Rosengaus et al. donation to initiate an allofeeding stomodeal event 1986; Cabrera and Rust 1999; Sheets et al. 2000; Suarez perhaps, indicating it has little nutritional value. We and Thorne 2000a, 2000b; Saran and Rust 2005). also observed termites that displayed no previous ac- Liquid held in the labial gland reservoirs of R. san- tivity, as conÞrmed by review of video for 2 min prior, tonensis is taken from sources outside the body and suddenly begin chewing. The material was assumed to used both to moisten building material and maintain be regurgitated because it was thin, clear, and unlike humid conditions within the network of galleries the white pulp typically seen in autofeeding ␣-cellu- (Grube et al. 1997, Grube and Rudolph 1999). Labial lose. This is the Þrst delineation of R. flavipes workers gland secretions also are involved in chemical com- “recycling” gut contents by regurgitation and this munication including feeding site selection (Kaib and route represented 16% of the “consumption” or feed- Ziesmann 1992, Reinhard et al. 1997, Reinhard and ing events (n ϭ 1237) recorded in our study. Kaib 2001). We propose that our observations support Worker-to-worker allofeeding was observed to in- the hypothesis that chewing exudes a feeding-stimu- volve three phases: initiation, procurement, and chew- lus, perhaps including labial and/or salivary gland con- ing. Allofeeding was observed to be a recipient-driven tents. The hypothesis of a chemical signal Þts the processÑ100% initiated by antennation followed by observation that recipient-workers moved directly to eventual mouthpart contact with the donor. Initiation a chewing nestmate to initiate an allofeeding stomo- always involved either antennation and/or allogroom- deal event. There was little attraction to workers ing. Approximately 50% of allogrooming events ended chewing autofeeding regurgitation, which repre- in an allofeeding donation. Allogrooming preceded sented 1.3% of all allofeeding events. The rarity with half of the proctodeal and two-thirds of stomodeal which we observed sharing of regurgitated material allofeedings. The antennation that preceded allofeed- cannot be explained by the behavior of the potential ing always involved the body part of the donor used in donors because all chewing termites acted the same. the donation, and it provided equivalent durations It seemed that there was simply no interest on the part proceeding either proctodeal (1.5 Ϯ 0.61 s) or stomo- of the potential recipientsÑas if termites were not deal (1.1 Ϯ 0.68 s) allofeeding. Allofeeding stomodeal chewing. It should be reiterated that termites was observed to always involve a donor that was al- “ ” autofeeding allogrooming were never solicited and ready chewing material obtained by four of the afore- therefore never shared that material. mentioned Þve routes of food acquisition. Termites It was observed that allofeeding proctodeal recip- autofeeding ␣-cellulose were donors in 39.1% of allofeeding stomodeal events. However, allofeeding ma- ients often completed the event with a quick and terials made up the majority of stomodeal donations, sudden separation of mouthparts from the anus of the with 32.4% taken from termites chewing after allofeed- donor. Three anecdotal observations further illustrate ing proctodeal and 27.3% from those chewing al- the “sticky” nature of proctodeal material. On one lofeeding stomodeal. The remaining 1.3% of allofeed- occasion, a termite backed into another termiteÕs leg ing stomodeal events involved termites autofeeding and was instantly stuck as evidenced by the lateral Ϸ regurgitation. movement of the stuck termite for 1 cm before Procurement of proctodeal material (8.1 Ϯ 36.5 s) separation. A second involved a termite that seemed took more time than stomodeal (6.8 Ϯ 15.6 s) and was to glue itself to the chamber ßoor by backing into it characterized by movement of donor mouthparts in immediately after a proctodeal donation. The stuck contact with the appropriate recipient body part. termite struggled for several seconds before it was able Time spent chewing proctodeal donations before con- to separate from the ßoor and move freely. We also sumption was slightly less (137 Ϯ 168 s; median 72 s) recorded a worker that obtained proctodeal material than allofeeding stomodeal (167 Ϯ 188 s; median from a nestmate, but the separation was not clean. A 103 s). Autofeeding ␣-cellulose powder was the most thin strand of material could be seen connecting the time-consuming food-procurement activity we re- two that quickly became rigid, as evidenced by syn- corded (184 Ϯ 169 s; median 122 s). chronous movement of the donorÕs abdomen and the The traditional deÞnition of trophallaxis has its ob- recipientÕs head for 80 s after the completion of the servational roots in food exchange between adult and proctodeal event. Proctodeal transfers have been larval Hymenoptera (Wilson 1971). Stomodeal tro- cited as a mechanism for reestablishing the hindgut phallaxis used in reference to termites often assumes fauna lost during molting (Weiss 2006). The Þrst feed- a two-way exchange of materials (Nalepa 1994, ing observed by freshly molted termites (n ϭ 2) was Cabrera and Rust 1999, Valles and Woodson 2002), allofeeding proctodeal and occurred within 10 min of although others have deÞned it as a one-way transfer the conclusion of ecdysis. Based on our observations, of alimentary liquids (Suarez and Thorne 2000a, we propose that the viscous, sticky nature of proc- 2000b). In our observations, stomodeal allofeeding todeal material serves to protect protists during trans- seemed to be a one-way transfer, although a two-way port through the upper alimentary tract in newly exchange would have been difÞcult to detect because molted individuals. September 2007 WHITMAN AND FORSCHLER:SHORT-LIVED BEHAVIOR BY R. flavipes 769

In conclusion, behavioral observations can address lofeeding stomodeal. Unaltered consumables (457 questions affecting numerous aspects of biology and autofeeding cellulose and allogrooming of 1,237 con- this manuscript illuminated additional avenues of in- sumption events) make up 37% of the worker diet, quiry examining a diversity of topics involving sub- whereas the remaining 60% is partially digested (both terranean termite biology. The frequency of mating allofeedings and autofeeding regurgitated). Assuming reported herein corroborates statements by Raina et that time spent in the different major feeding cate- al. (2003) and Costa-Leonardo and Patricio (2005) gories was indicative of amounts consumed (medians that morphology can be used to infer mating fre- for autofeeding cellulose, 122 s; autofeeding regurgi- quency. Additional work on the relationship between tated, 23 s; allofeeding stomodeal, 103 s; and allofeed- mating and egg laying also would resolve whether the ing proctodeal, 72 s) easily half the food consumed by incidence of mating we observed in three laboratory worker termites involves substrates subjected to a cultures without eggs is typical of reproductive pairs digestive process before acquisition. in that segment of the egg-laying cycle. Clearly egg The frequency and type of allofeeding we described laying is not a daily occurrence in the rhinotermitids, also has implications for interpreting toxicant transfer and models of colony growth should account for this data that often provide equivocal results (Ibrahim et phenomenon. al. 2003, Remmen and Su 2005). Our observations, for The conclusion that ecdysis in Reticulitermes is a example, could explain the “less than expected” trans- group-assisted event should be acknowledged as im- fer of [14C]sucrose by termites in a recent study (Sa- portant for understanding the evolution of eusociality ran and Rust 2005). Their experimental design fed (Thorne 1997) in addition to partially explaining col- donors and recipients in different arenas thereby per- ony-level immune response as inßuenced by group mitting transfer by two food acquisition schemes: al- size (Rosengaus et al. 1999b, Traniello et al. 2002). The lofeeding proctodeal and autofeeding allogrooming. observation that 15 termites consumed the exuvia Two other routes, allofeeding stomodeal from nest- should increase the accuracy of toxicant-transfer mod- mates autofeeding regurgitation and consumption of els, including group-assisted molting. Our observa- exuvia, are possible but occurred at such low fre- tions on group-assisted molting suggest recognition of quency that their impact would be negligible. The intoxicated workers could be manifested by jack- presence of salivary cellulase (Nakashima et al. 2002) knifed cadavers in bioassay and further work could and removal of sugars in the alimentary tract supports illuminate how communication of health-status im- the hypothesis that the experimental design used by pacts toxin transfer. The literature contains comment Saran and Rust (2005)) would have shown very little on cannibalism in toxicant transfer without quantify- trophallaxis of [14C]sucrose. ing the incidence or impact (Su and Scheffrahn 1993, “ ” Our observations on OMs have described a response Sheets et al. 2000, Valles and Woodson 2002). We did to this behaviorÐthat of the type IV with defecationÑ not observe cannibalism in the current study, but have noted it in bioassay control groups using paint-marked and detailed the similarity of the movements involved termites (B.T.F., unpublished data). The cues that in OMs and feeding/excavation behavior. It is our lead to cannibalism in subterranean termites also hope that describing the mechanics and incidence of needs further study. behaviors obtained in this study will stimulate further The role that pill formation/deposition plays in gal- research. lery construction with its attendant oral manipulation of the substrate opens new approaches to understanding termite foraging behavior. The mechanics of gal- References Cited lery construction through pill formation should be considered when modeling foraging, interpreting ter- Afzal, M. 1985. Courtship and copulation in the termite Bi- miticide tunneling bioassay data, and explaining ﬁditermes beesoni (Gardner) (Isoptera). 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