Louis M. Roth.
Oviposition Behavior and Water Changes in the Oöthecae of Lophoblatta brevis (Blattaria: Blattellidae: Plecopterinae).
Psyche 75:99-106, 1968.

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OVIPOSITION BEHAVIOR AND WATER CHANGES
IN THE OOTHEC~AE OF LOPHOBLATTA BREVIS
(BLATTARIA : BLATTELLIDAE : PLECTOPTERINAE)* BY Louis M. ROTH
Pioneering Research Laboratory, U. S. Army Natick Laboratories, Natick, Massachusetts 01 760
Oviposition behavior and changes in the water content of cock- roach oothecae during development of the eggs has been related to the evolution of ovoviviparity and viviparity in the Blattaria (Roth and Willis, 1955a, 1958; Roth, 1g67a, 19671)). Based on the shape of water uptake curves, I suggested (1967a) that ovoviviparous cock- roaches (Blaberidae) may have evolved from blattellid-like ancestors whose oothecae I ) had low water contents ( <W%} initially, 2) were carried externally until the eggs hatched, and 3) had S-shaped water uptake curves during embryogenesis. This stage in the evolu- tion of ovoviviparity was indicated with a query (Roth, 1967a, Fig. 14) because no species was known to fit the category. At that time, the only forms known that carried their eggs externally for the entire embryogenetic period were species of Blattella, Chorisia fulvo- testacea Princis, and a third questionably identified genus (Roth, 19671') ; these are members of Blattellinae, genera of Blattellidae which rotate their oothecae go0 after they are formed. The oothecae of Blattella and Chorisia initially have a high water content (usually >56%), and do not have an S-shaped water uptake curve; I sug- gested that they could be placed more logically in the pathway for the evolution of viviparity than for that of ovoviviparity. Among the cockroaches I collected in the Amazon (see acknowl- edgements) was a female of Lophoblatta brevis Rehn. It was taken on a banana plant in the town of Moura, on the Rio Negro, July 21, 1967. The female was carrying an ootheca with the keel upright and the eggs hatched the day after the specimen was collected. The otitheca of Lophoblatta is not rotated and this plus other characters places this genus in the Plectopterinae of McKittrick (1964) ; it is the first plectopterine genus known which carries its ootheca until the eggs hatch.
The ootheca of L. brevis is relatively thin, contains very few
crystals of calcium oxalate, and the serrations of the keel are greatly reduced (Fig. 3). The egg case has an unusual shape, being wider *Manuscript received by the editor March 20, 1968



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Figs. 1-6. Oiithecae of LofhoblaHa spp. Figs. 1-3. L, brrvh. Fig. 1. Lateral view (Xl2). Fig. 2. Dorsal view (X 11.5). Fig. 3, Portion of keel region (X 67.6). Figs. 4-6. L. arlei. Fig. 4. Lateral view (X 9.4). Fig. 5. Dorsal view (X 9.4). Fig. 6, Portion of keel region (X 67.6). The keel region (Figs. 3 and 6) is an inner view of one half of the oothecal wall, cleared in xylene and mounted in Permount. In Fig. 3, the protruberancea (arrow) are spongy-like bodies, normally found above each egg; in Fig. 6, these bodies were removed to show the actual margin of the keel. The main part of the keel (double-beaded arrows) lies flat against the eggs and only the small reduced serrations protruda upwards. than high, and somewhat flattened dorsally and ventrally (Figs. 1, 2). It does not appear to increase in size or change shape as the eggs develop. The end of the &theca in the vestibulum of the fe- male is lighter in color than the remainder of the egg case and ap- parently is permeable to water. Except for its unique shape, the Stheca of L. brevis resembles that of some species of Blaitella. Other species of Lophoblalta have thick, hard Gthecae that are deposited shortly after their formation (Roth, 1968a : Lophoblatta sp. A = Lophoblatta fssa Saussure and Zehntner, Fig. 76; and Lophoblam



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19681 Roth - Oothecae of Lophoblatta 101 sp. B, Fig. 78). Perhaps, a closer study of LophobZatta may reveal sufficient differences in species like L. brevis to warrant placing them (or the others) in different genera. The dorso-ventral flattening of the ootheca of L. brevis and L. arlei (see below) may have adaptive significance in that it would allow the female to rest or crawl into more narrow spaces and re- duce the chances of losing the oothecae prematurely, than if the egg cases were of the usual shape
(i.e., taller than wide) and carried
with the long axes of the eggs in the vertical position. Females of Blattella germanica (L.) that carry the ootheca in a horizontal posi- tion could crawl into a space which averaged 0.4 of a mm. narrower than females that were still carrying the egg case ~er~endicularly (i.e., before rotation) (Wille 1920). The adaptive value of rota- tion in the Blattellinae may well be to allow the female to crawl into narrow crevices while carrying its ootheca, and also to reduce the chances of the egg case being knocked off accidentally while crawling in these narrow spaces. In the ovoviviparous Blaberidae, rotation of the ootheca reorients the eggs so that their long axes lay in the plane of the cockroach's width and would thus allow for growth of the eggs by stretching the uterus, principally in a lateral direction, in insects that are usually quite flat (Roth, 1967b). The significance of rotation of the ootheca in the oviparous Blattellidae differs from its importance in the ovoviviparous and viviparous Blab- eridae, but its occurrence in oviparous forms preadapted them for the evolution of species which incubated their eggs internally. A colony of L. brevis was established from the female collected in Moura, and from another female in Puraquequera, Rio Negro, July 3 I, 1967. Water determinations were made on Gthecae of different ages (removed from females at various times after oviposition). The results are shown in Fig. 7. The initial water content of the ootheca is about 36%. Little change in this percentage takes place until about the ninth day. A marked increase in water content occurs between days 9 and 11, followed by a more gradual rise in percentage of water until just before the eggs hatch, at which time it reaches about 75%. The water uptake curve is S-shaped as was predicted (Roth, 1967a) and compares well with other plectopterines that drop their oothecae after forming them and which have <50% water at the time of oviposition (see Roth, 19673. Fig. 3). The shape of the water uptake curve also is very similar to that of the ovoviviparous cockroach Nauphoeta cinerea (Olivier) (see Roth, 1967a, Fig. 8). The ootheca of L. brevis is carried for 31 to 34 days (Figs. 9, and after the eggs hatch a new eggcase is formed 9 to 10 days later.



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Psyche
Lophoblatta brevis
14
a ft å
5 10 15 20 25 30 3 5
AGE IN DAYS
Fig. 7.
Changes in water content, with age, in the oothecae of Lophoblatta brewis. Arrows indicate days when eggs hatched. The first adults appeared in the culture in 84 to 85 days after the eggs hatched. After the first ootheca oviposition occurs about every 40 to 44 days. If the ootheca is removed manually from the female prematurely, a new ootheca is formed much earlier than it would be if the eggs were allowed to remain attached to the female until hatching. The younger the age of the ootheca when detached from the female, the longer it takes to form a new egg case (Fig. 8). Recently formed Gthecae that are removed from the female lose water rapidly and the egg case collapses. These results are similar to those obtained with Blattella germanica (L.) and Blattella vaga (Roth and Stay, 1962) and show that the presence of an ootheca in



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19681 Roth - Oothecae of Lophoblatta 103 the vestibulum of the female inhibits the development of the ovaries. The inverse relationship between time of removal of the ootheca and time required to ovulate again can be explained by the fact that the basal oocytes in females carrying eggs near hatching time are larger than those in females that have recently oviposited and, therefore, less time is required for the oocytes to mature once the inhibiting influence of the ootheca is removed (Roth and Stay, 1962). At the time of ovulation, the ovariole of L. brevis contains only one oocyte in Zone V, and there are only 6 oocytes in Zone IV. Thus, the ovariolles resemble those of oviparous Blattella and Chorisia and certain Blaberidae (Roth 1968b).
AGE OF OOTHECA WHE.N DETACHED
Fig. 8. Relationship between age (days) of the oothecae when removed from the female and the time required by Lofhoblatta brevis to ovulate again.




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104 Psyche [June
The structure of the Gtheca and ovaries, as well as oviposition behavior of Laphobhifa brevis indicate that, with the exception of rotation of the olitheca, reproduction in the FIectopterhae has evolved along the same general pathway as that which occurred in the Blat- tellinae* However, at the time of oviposition, most plectopterine o4thecae have <SO% water whereas the Blattellinae have >SO% water. Although the water uptake curve of the plectopterine L. brevis can be used as an example to link the oviparous Blattel1ida.e with the ovoviviparous BIaberidae, it is likely that ovoviviparity arose from a Elattdinae-like form because rotation of the &them was a pre- adaptation necessary for the evolution of the BIaberidae (Roth, ig67b). Because the initial water content of the otithecae of prac- tically all Blattellinae examined have been found to be more than 50%, I suggested that viviparity (in the only viviparous species known, Diphpter~ punctata (Ed. ) the eggs initially contain about 65% water) arose from a blatteHine stock and B/atteZla spp. was an important 'link between oviparous and viviparous forms (Roth, Figs. 9-10.
Dorsal and ventral views of a female of Laphablatta brevis, carrying an Gtheca (line = 3 mm.).




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19681 Roth - Oiithecae of Lophoblatta 105 1967a). However, it is probable that there are Blattellinae whose oothecae contain <50% water initially, which are carried attached externally by the female for the entire embryogenetic period, and which have an S-shaped water uptake curve. Such blattellines when eventually found will add additional support to the hypothesis that ovoviviparity also arose from a blattellinae-like stock. Lophoblatta arlei (R. S. - Albuquerque) , a closely related but much larger species than L. brevis, was collected in an oriole nest near Serra Tamendaui, Rio Negro, July 18-19, 1967. Its ootheca is similar but larger (Figs. 4-6) than that of L. brevis, and it too is carried externally for the entire embryogenetic period. The water content of the ootheca when first formed is 38.6ko.o (N = 2). Calcium oxalate crystals appear to be absent, or if present, are very sparse in the wall of the ootheca. There is only I oocyte in Zone V, and '; in Zone IV of the ovariole. Unfortunately, I could
not establish a culture of this species, but, undoubtedly, water up- take is similar to that of L. brevis.
SUMMARY
The blattellids Lophoblatta brevis, and L. arlei are the first mem- bers of the Plectopterinae found that carry their otothecae externally until the eggs hatch. Except for the absence of rotation of the ootheca, their oviposition behavior is similar to Blattella and Chorisia, both genera of Blattellinae.
The structure of the ovaries and ootheca, as well as the oviposi- tion behavior of L. brevis and L. arlei show that, except for not rotating the ootheca, reproductive evolution in the Plectopterinae has followed the same general pathway as that undergone in the Blattellinae.
The water uptake curve of the eggs in the ootheca of L. brevis is sigmoid-shaped and typical of species that have a low water content ( <50%) at the beginning of embryogenesis. This is the first dem- onstration in the Blattellidae that the curve for water uptake by eggs in an externally carried ootheca can be S-shaped and similar to ovoviviparous species that incubate their eggs internally. Because rotation of the ootheca was a necessary prerequisite for the evolution of ovoviviparity in the Blaberidae, Blattellinae-like species were probably the forerunners of this family. However, though they likely exist, no Blattellinae are known whose oothecae initially have low water contents, are carried by the mother during embryogenesis, and whose eggs have an S-shaped water uptake curve.



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Psyche
ACKNOWLEDGEMENTS
I thank Dr. Ashley Gurney for determining the species. The
specimens were collected in Brazil during Phase C of the Alpha Helix Expedition to the Amazon in 1967.
I am grateful to the
National Science Foundation for support on the Amazon Expedition under grant NSF-GB-59 I 6.
REFERENCES CITED
MCKITTRICK, F. A.
1964. Evolutionary studies of cockroaches. Cornell Univer. Agric. Exp. Sta. Mem. 389, 197 pp.
ROTH, L. M.
1967a. Water changes in cockroach oothecae in relation to the evolution of ovoviviparity and viviparity. Ann. Entom. Soc. Amer. 60: 928-946.
1967b. The evolutionary significance of rotation of the ootheca in the Blattaria. Psyche 74: 85-103.
1968a. Oothecae of the Blattaria. Ann. Entom. Soc. Amer. 61: 83-111. 1968b. Ovarioles of the Blattaria. Ann. Entom. Soc. Amer. 61: 132-140. ROTH, L. M. and B. STAY
1962. Oocyte development in Blattella germanica and Blattella waga (Blattaria). Ann. Entom. Amer. 55 : 633-642. ROTH, L. M. and E. R. WILLIS
1955a. The water content of cockroach eggs during embryogenesis in relation to oviposition behavior. Jour. Exp. Zool. 128: 489-509. 1958. An analysis of oviparity and viviparity in the Blattaria. Trans. Amer. Entom. SOC. 83: 221-238.
WILLE, J.
1920. Biologie und Bekampfung der deutschen Schabe (Phyllodromia germanica L.). Monogr. Angew. Ent. Nr. 5, Zeit. Angew. Ent. Beiheft 1, Band 7, 140 pp.




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