Neuroendocrine deficiency effects on trophic metabolism and water balance in the cockroach, Blaberus discoidalis

J. Insect Physiol., 1975, Vol. 21, pp. 501 to 510. Pergamon Press. Printed in Great Britain

NEUROENDOCRINE DEFICIENCY EFFECTS ON TROPHIC METABOLISM AND WATER BALANCE IN THE COCKROACH, BLABERUS DISCOIDALIS LARRY

L. KEELEY

Texas Agricultural Experiment Station, Department of Entomology, University, College Station, Texas 77843, U.S.A. (Received

24 June

Texas A & M

1974)

Abstract-Unoperated, sham-operated (SO) and allatectomized (CA-) adult, male Blhberus discoidalis lost cu. 300 mg of live weight (LW) during the first 10 days after ecdysis. This decrease resulted from losses in both dry weight (DW) and water. An additional 100 mg LW loss was found in allatectomizedcardiacectomized (CA-+CC-) animals as a result of increased water loss. The LWs of operated and unoperated controls remained nearly constant between 10 and 30 days of age as DW increased and water decreased in comparable amounts. However, the LW of 30-day-old CA-+ CC- animals was 100 mg greater than the controls due to increased water retention. Compared to controls, food consumption and faecal production were reduced by 50 per cent in CA- and CA-+ CC- animals, but the percentage of food digested was unchanged. Efficiency of converting food to DW in CA-+ CC- animals was twice that of SO and CA- animals and four times that of the unoperated controls. These results indicate that extirpation of the retrocerebral complex decreases food intake but not digestion. Nutrient storage or conversion to body matter is apparently enhanced by neuroendocrine deficiency. Therefore, a gross nutritional deficiency is unlikely in CA- + CC- animals. The LW changes occurring after neuroendocrine deficiency were related to changes in water content. DW changes were comparable in all control and experimental groups. The results indicate both diuretic and antidiuretic effects by the neuroendocrine system depending on the age of the animals. INTRODUCTION

THE FEEDINGactivities of insects often act as a stimulus for the release of neurohormones. WIGGLESWORTH (1934) demonstrated that feeding initiated the moulting process in Rhodnius prolixus. Blood engorgement of Rhodnizks activated abdominal stretch receptors which neurally stimulated the brain to release ecdysiotropin. A similar series of events was postulated for Locusta migratoria migratorioides where swallowing activated pharyngeal stretch receptors to stimulate the release of stored neurohormones from the corpora cardiaca (CLARKE and LANGLEY, 1963). Recently KEELEY (1974) reported that prevention of chewing or swallowing by oral blockage inhibited a neuroendocrine-mediated phase of respiratory maturation in the fat body mitochondria of adult Blaberus discoid&. Lack of 501

502

LARRY

L. KEELEY

food and/or water did not prevent the mitochondrial development. The above reports suggest that chewing, swallowing, or stretching of the pharynx or crop of insects cause neural stimuli which result in the release of neurohormones. Neurohormones reportedly influence insect digestive processes. Corpora cardiaca extirpation (CC-) reduced midgut protease activity in C~~Z~~~~~~y~~~ocephala (THOMSEN and MOLLER, 1963). However, ENGELMANNand WILKENS (1969) demonstrated that reduced protease activity in the midguts of neurosecretory cell extirpated (NSC-) Sarcophaga bullata resulted from decreased food intake caused by operational trauma rather than neuroendocrine deficiency, EN~EL~NN (1968) reported a similar 50 per cent decrease in food consumption after CC- of Leucophaea maderae. DOGRA and GILLOTT (1971) reported that stored neurosecretory materials were released 20 min after feeding in starved, female Melanoplus sanguinipes. This response was followed several hours later by increased synthesis of intestinal protease. However, they failed to show that the increased protease levels were a direct response to the, release of the neurohormones. The above studies indicate that neurosecretory oscillations may influence digestive processes through effects on food consumption or the efficiency of its digestion. Neurohormones regulate the levels of insect basal metabolism. SLAMA (1964) found allatectomy (CA-) stopped reproduction and reduced the respiration of female ~y~~oc~~ aptem. CC- further reduced the respiration of ~yr~~oco~~. SLAMAinterpreted this to mean that CA- reduced reproduction-related metabolism while CC- decreased ‘trophic’ (digestion and basal) metabolism. CONRADILARSEN(1970) reported that the respiration of Oneopel& fascia&s decreased after feeding on a nutritionally deficient diet (3 per cent glucose) or after NSC-. Subsequent feeding on milkweed seeds increased the respiration of glucose-fed U~op~l~~ but not that of NSC- insects. Both studies indicate trophic functions and basal metabolism decrease after NSC-, but neither study discriminates between primary and secondary events. The decreases in basal metabolism may result from nutritional deficiencies following the previously discussed reductions in feeding, digestion, and absorption that occur after NSC-. CA- + CC- decreased whole body respiration by 24 per cent in adult, male Blabems (KEELEY and FRIEDW, 1967). Later, this decrease in whole body respiration was shown to reflect a decrease in the respiratory enzyme activities of fat body mitochondria (KEELEY, 1972). The disruption in fat body mitochondria after CA-+ CC- may result from decreased trophic functions, since WALKER (1965) reported that starvation caused a structural degeneration of fat body mitochondria in ~~ub~us. Indeed, CA--l- CC- drabs lost up to 25 per cent of their live weight during the first 10 days after surgery, indicating an initial period of starvation (KEELEY and FRIEDMAN,1967). By 30 days, both their live and dry weights had returned to normal, showing a resumption of feeding activity. Nevertheless, respiration did not return to normal. Considering the changes that occur in food consumption and digestion after neuroendocrine disruption in other insects, the lack of mitochondrial development

NEUROENDOCRINE EFFECTS ON TROPHIC METABOLISM AND WATER

503

in the ~~~ fat body could result from a nutritional inadequacy rather than from an endocrine deficiency. Therefore, the folfowing studies were undertaken to clarify the effects of sustained neuroendocrine deficiency on food consumption, digestion and utilization in adult, male Blaberus. STORIES

AND METHODS

Experimental animals were newly ecdysed, adult, male B. discoidalis, Rearing and glandular surgical procedures have been described previously (KIZELEYand FRIEDMAN, 1967). All surgery was performed within 24 hr of adult ecdysis (0 day old). The integrity of the recurrent nerve was substantiated in all cases of endocrine surgery. Studies on weight changes and e@ciency of food convex&n For weight studies and studies on food consumption and faecal production, O-day, experimental animals were placed in 17 x 26 x 13 cm plastic rat cages with fresh wood shavings. The body weight gain-loss experiments were also used to determine if endocrine deficiency had any effect on food consumption, digestion and conversion to body matter. Preliminary observations indicated B~&YZG adults did not eat for the first few days after ecdysis. The crops of newly ecdysed adults contained no food but did contain a considerable amount of cuticular debris. This material had moved into the midgut by 4 to 5 days after ecdysis.The experimental groups used in the weight change experiments were starved between 0 to 10 days to permit the gut to clear so that the faecal pellets collected to measure food conversion did not consist of the materials in the gut at ecdysis. Water was presented ad lib. throughout the experiment. At 10 days all cages were cleaned and a weighed amount of dog food was added to each cage along with fresh wood shavings. A similar sample of dog food was dried for 24 hr at 125 2 5°C to determine its dry matter content for calculating the amount of dry food added to each cage. At 30 days the animals, remaining food and faecal pellets were removed and dried 24 hr at 125°C to determine final dry weights. Animals used in-the weight studies to show changes in live weight (LW) and dry weight (DW) were weighed initially and again at the termination age and dried to constant weight as described. Statistics are based on Student’s t-test using the unoperated group as the control for comparison. RESULTS

Live weight changes Initial studies measured the changes in live weight (LW) in response to endocrine gland extirpation. Using O-day LW as the base value, the data in Fig. l(A) show the changes in LW with adult age. In unoperated controls, a LW loss normally occurred during the first 10 days after adult ecdysis during which time food was not provided. This loss was between 200 and 300 mg or 10 per cent of

504

LARRY

L. KEELEY

the LW for this 2000 mg insect. LW loss in sham-operated (SO) and CAgroups was similar to the unoperated control group. By comparison, the IO-day LW loss of CA-+ CC- animals was about 406450 mg or about 20 to 25 per cent of the total LW. This additional LW loss was significant when compared to both the SO (PC O-01) and unoperated (PC O*OOl) controls. The LW changed little in the SO or CA- surgery control groups during the lo- to 30”day period. The LW of CA-+ CC- animals had increased by the fifteenth day, and from then on until the thirtieth day did not differ signi~~antly from the unoperated controls. (Q)

(b) 1 Food.ad libitum

Food abeen? 300

_

fP
200

IO0

100

z

0

0 400

Unoper. [I 01 O-SRam.oper [I 01 *-Al latect. 191 q-Allatect. 5 Cardiacecti81 l-

nn

-JYY

%

5

IO

Days after

15

20

25

30

adult ecdysis

FIG. 1. Time-dependent changes in the live weight of adult, male B. discoidalis. Weight changes are based on differences from either the O-day weight (A) or the lo-day weight (B). Numbers in brackets indicate numbers of animals tested. F-values shown in parentheses are based on Student’s t-test between the experimental and unoperated control groups. Lack of a P-value indicates no significant difference from unoperated controls.

The data in Fig. l(B) used the lo-day LW as a new base to show LW changes following the presentation of food. The results indicate little change from the unoperated controls for LW gained or lost in either the SO or CA- groups. In contrast, immediately after the addition of the food, the CA-+ CC. group showed a 100 mg LW increase which did not change until days 25 to 30 when a further 190 mg LW gain occurred. Dry weight a;7adwater changes It was essential to determine whether the fluctuations in LW after CA-+ CCreflected changes in the dry weight (DW) or water content of the animals. To

NEURORNDOCRINE EFFECTSON TROPHICMETABOLISMAND WATER

505

determine which was affected, it was necessary to know the absolute LWs, DWs and percentages of dry matter at the various ages. These values could be obtained only be sacrificing replicate groups of appropriately aged animals. This required predetermination of the variability in weights between replicate groups in order to ensure reliability in their estimated weight changes. The data in Table 1 show the range of LWs and DWs of comparable groups of Blabems. These were found to be within a reasonable biological variability of 10 per cent. For example, the range of LWs between all the groups at 0 day was only 223 mg, a value + 5 per cent of the group mean of 2243 mg. Likewise, comparable IO-day-old groups consistently lost similar amounts of LW. TABLE ~-EFFECTS -OF STARVATIONAND ENDOCRINESURGERYON THE BODY COMPOSITIONOF ADULT MALE B. discoidalis

(1)

Age

Experimental group

Stamed

at termination

O-10 days; food lo-30

Unoperated Unoperated so (10) CA- (10) CA- + CCUnoperated so (10) CA- (9) CA- + CC-

(10) (10)

(8) (10)

(8)

(2)

O-Day body wt

Final body wt

(mg)

(mg)

days

(3)

(4)

(5) %DWof final LW

ALW (mg)

0 10 10 10 10 30 30 30 30

2224 rl:89 2298 + 83 2176 + 78 2216 + 62 2170 + 81 2280 + 75 2234 + 83 238lk 64 2307 t 69

-

-

2016 + 75 1942259 1953256 1758 + 75 1988 + 92 2043 rl:75 2071 f 72 2113 +61

-283+28 -234+26 -263 i:27 -411 f 50 -292k75 -191+71 -3lOk54 -194f65

714+40 654 zk 39 617 + 38 652 + 23 605 + 35 693 + 41 683 _+29 690 + 30 674+15

32.0 + 0.8 32.3 + 0.9 31.5 + I.2 33.4 fi 0.8 34.4 * 1.3 34.9 + 0.6 33.4+0.6 33.2 f 0.7 32.2 + 0.6

10 10

2228k85 2158586

1938+90 1780296

-290+21 -378+31

650+39 615~28

33*4+0*8 34.7 + 0.8

Food O-10 days Unoperated (7) CA- + CC- (7)

Numbers in parentheses indicate numbers of animals tested. Values are means + S.E.

Because of the consistency between the groups and the reproducibility in weight changes observed at the various ages, it was possible to estimate the LW parameters undergoing fluctuations. Differences between the 0-, lo- and 30-day LWs and DWs permitted estimations of the dry matter and water changes (Table 2). For example, based on DW changes between 0 and 10 days for the unoperated and CA-+ CC- animals, the unoperated animals lost 84 mg of dry matter compared to 92 mg for CA-+ CC- animals. This suggested that of the additional 128 mg LW lost by the CA-+ CC- group, 120 mg was water and only 8 mg was dry Therefore, the increased water loss was a specific response to CC matter. deficiency. However, 69 mg of the original DW loss in the CA-+ CC- animals 17

506

LARRY L. mI.RY

was recovered by 30 days, and the 30-day DW of CA-+CCanimals was comparable to both the unoperated and surgery controls. The LW of CA- + CCanimals increased by 217 mg between 10 and 30 days. Since only 69 mg of the increase was DW, the other 148 mg was water. In contrast, all the control groups showed further water loss between 10 and 30 days offset by a DW gain thus resulting in no significant net LW change (Fig. 1A; Table 2). TABLE~-ACTUAL ANDESTIMATED CHANGES IN DRY MATTERANDWATERCONTENTOF ADULT, MALEB. discoidalis IN RESPONSE TO ENDOCRINE SURGERY

(4 Age

Experiment Starved

span studied

Estimated O-day DW1 (mg)

(b)

(4-t

(4

Actual DW at termination (mg)

Actual ALW (mg)

Estimated ADW: O-IO days2 or IO-30 days3 (mg)

(4

Estimated Awater : O-IO days4 or 1O-30 days5 (mg)

O-IO days; food IO-30 days

Unoperated

O-IO IO-30

738

654 693

-283 - 292

-84 +39

- 199 -48

so

O-IO IO-30

699

617 683

- 234 - 191

-82 +66

-152 -23

CA-

O-10 IO-30

711

652 690

- 263 -310

-59 +3s

- 204 -85

CA-+CC-

O-IO IO-30

697

605 674

-411 -194

-92 +69

-319 +I48

O-IO O-IO

715 693

650 615

- 290 - 378

-65 -78

- 225 - 300

Food O-IO days Unoperated CA-+CC-

Calculations used in estimating weights (small letters in parentheses refer to those above the columns): 1 Est. O-day DW = O-day LW of experimental group x 0.32 (DW/LW of the O-day group in Table 1). 2 ADW O-IO days = (a),_,, days- (h),_,, dasB. 3 ADW lo-30 days = (b),,,, days- @Lo days. 4 AWater O-10 days = (c)o-10 days- (d),_,, days. ’ AWater IO-30 days = C(c)10_30 davg- (4a-lo da& - (d)10-80ditys. + From Table I, column 3.

The presence of food during the 0- to lo-day period had no affect on observed weight losses. The LWs and DWs of 0- to lo-day starved, unoperated and CA-+ CC- groups were identical to the LWs and DWs of groups fed during the same period (Table 1).

NEUROENDOCRINE

EFFECTS ON TROPHIC METABOLISM

507

AND WATER

Food consumption, digestion, and conversion The data on the amounts of food consumed, faeces produced, per cent digestibility and efficiency of conversion are shown in Table 3. Unoperated and SO controls had comparable food consumption, faecal production, and values for digestibility. The CA- and CA-+ CC- groups were considerably different from the controls. They consumed half as much food and produced half as much faeces. However, the ratio of food : faeces was proportional to the surgery controls so no significant change was noted concerning the digestive capacity as a result of endocrine deficiencies_ TABLET-EFFECTS DIGESTIBILITYAND

OF GLAND DEFICIENCY ON FOOD CONSUMPTION, FARCAL PRODUCTION, CONVRRSIONTO BODY MATTER FROM THE PERIOD OF 10 TO 30 DAYS OF AGE l2W DW Estimated ADW lo-30 days Approximate Food consumption Faecal production (mg/animal) (mg/animal) (Table 2) ECD+ digestibility*

Experiment Unoperated (10) so (10) CA- (8) CA-+CC(9)

70 72 77 80

87 80 30 27

295 284 131 137

+39 -t66 +3s +69

19 -32 38 63

* Approximate digestibility =

DW food ingested - DW faeces x 100 DW food ingested

(WALDBAUER, 1968).

t Efficiency of conversion of digested food to body matter Estimated DW gained (lo-30 =

(DW of food ingested)-(DW

days) of faeces)

x100

(WALDBAUER, 1968).

Data based on a pooled study consisting of the number of individuals shown in parentheses.

Digestibility reflects breakdown and absorption of the consumed food, but tells nothing concerning the efficiency of the animal in converting the food to body matter. This latter factor is reflected in the ECD coefficient (efficiency of conversion of digested food to body matter). The formula for ECD must be based either on the gain in LW or on the DW of a comparable group of animals (WALDBAUER, 1968). Changes in LW may reflect changes in water content rather than body matter. We know water changes considerably in the CA-+ CC- animals. Therefore, since the LWs and DWs are consistent between our different groups the estimated changes in DW between 10 and 30 days (Table 2) were used for determining the ECD (Table 3). No corrections were made for food and faeces remaining in the animal since the DWs of gut contents were measured in 30-day unoperated animals and found to comprise usually less than 6 per cent of the total animal DW.

508

LARRYL. KEELEY

The data in Table 3 indicate an ECD of 19 per cent for unoperated controls. The ECD increased by about twofold after surgery. The SO controls consumed the same amount of food-and produced the same amount of faeces as unoperated controls but gained more weight, CA- animals consumed half the food, produced half the faeces, but gained an amount of weight comparable to the controls, thus suggesting a twofold greater conversion. Finally, CA-+ CC- animals had food consumption and faecal production values comparable to CA- animals but gained twice as much weight. Therefore, the ECD of CA-+CCanimals was twice that of the operated controls and four times that of normal, unoperated animals.

DISCUSSION

This research indicates sustained neuroendocrine deficiency changes certain trophic-related aspects of insect intermediary metabolism. Food consumption and faecal production were reduced but percentage digestibility remained constant. The conversion of food to body matter increased and body water shifts were dramatic. The greater DW-ECD for CA-+CCanimals between 10 and 30 days of age probably reflected their decreased basal metabolism. Extirpation of the CC from Blabems depresses whole body respiration by 25 per cent and fat body respiration by 40 per cent (KEELEY and FRIEDMAN, 1967). This reduction in metabolism apparently resulted in nutrient storage rather than its expenditure for energy production. Even though the CA- + CC- groups consumed 50 per cent less food; they were more efficient at converting it to body substance. The CAanimals also consumed 50 per cent less food, but compared to the DW gain of the CA-+ CC- group, the CA- groups gained only 45 per cent. Our earlier data indicated CA- had no effect on the respiratory metabolism so that consumed food probably was expended more rapidly and no net gain in body matter occurred. Surgery appeared to stimulate food conversion to body matter. The SO and CA- groups had ECD values of twice the unoperated controls. No reason can be suggested at this time for this increased nutrient storage other than an injury induced stress response. There was no evidence of reduced digestion after glandular extirpation of Blabems. Our results indicate gland extirpations depressed food consumption by 50 per cent; however, faecal production remained proportional so that the overall percentage digestibility was unchanged. The raison S&e for reduced food intake after glandular extirpation of Blabems remains obscure, but it correlates to CA-, most likely as a response to removing the gland rather than the resulting endocrine deficiency. The results show the most significant action of CC- on changes in LW were However, the data are contradictory. the result of changes in water content. Initially after CA-+ CC-, water is lost suggesting the deficiency of an antidiuretic neurohormonal factor. Later, between 10 and 30 days, the opposite occurs in that water content increases in CA-+ CC- animals suggesting the absence of a

NBUROENDOCRINE

EFFECTS ON TROPHIC METABOLISM

AND WATER

509

diuretic factor. Neither change is noted after CA- or sham surgery so that both changes correlate to neuroendocrine deficiencies. The literature on the endocrine regulation of water balance in insects indicates antagonistic regulatory hormones from the same neurosecretory source. Both diuretic and antidiuretic brain neurohormones are reported (WALL and RALPH, 1965; WALL, 1967; MORDUE, 1969; JARIAL and SCUDDER, 1971). A similar contradictory situation exists for the ventral nerve ganglia. MADDRELL(1963) reported a diuretic hormone from the metathoracic ganglion. MILLS and WHITEHEAD (1970) reported b ursicon was identical to the diuretic hormone and was secreted by the last abdominal ganglion in Periplaneta. In contrast, antidiuretic factors were also described as originating from the ganglia of the ventral nerve cord (DELPHIN, 1963). These reports support our findings that endocrine factors from the brain regulate insect water content and that other factors, possibly from the ventral nerve cord, are involved. For example, during the first 10 days after imaginal ecdysis, the LW of Blabems normally decreases by 150 to 200 mg due to a water loss. This is in agreement with the release of a tanning diuretic hormone from the last abdominal ganglion (MILLS and WHITEHEAD, 1970). However, CC- results in a one and a half to twofold increase in the water loss suggesting that there may be an antidiuretic hormone in the brain-CC complex which is lost when the animal is cardiacectomized. In this way, the water content is balanced according to the titres of two antagonistic hormones released from different sources. The CA-+CCanimals appear to reverse their water balance between 10 to 30 days of adult age. In contrast to the water loss noted during the first 10 days, the older CA-+ CC- animal increased its LW due to water storage. This would suggest the Blabem brain-CC complex initially exerts an anti-diuretic effect; whereas, after 10 days, it may have a diuretic action. Considering that both types of water-regulating effects have been reported for the brain-CC complex, it is feasible that the particular effect is a function of age and/or physiological state. These findings indicate the reduced biochemical activities of fat body mitochondria are not the result of a gross nutritional inadequacy after sustained CA- + CC-. Although food consumption is reduced by CA-, efficiency of conversion to body matter is increased by CC-. Short-term starvation has no effect on the biochemicai development of fat body mitochondria and the development responds more to the endocrine balance than to nutrient lack (KEELEY, 1974). Therefore, our data continue to indicate that the decreased mitochondrial development in the fat body of CA-+ CC- BZabenu is related to a neurohormonal deficiency and not to a generalized biochemical pathology.

Acknowledgements-The author wishes to thank Drs. STANLEY FRIEDMAN and G. P. WALDBAUER for their critical review of the manuscript. This study was supported by

the Texas Agricultural Experiment Station and the manuscript approved for publication as Texas Agricultural Experiment Station Manuscript No. TA 11211.

510

LARRY L. KEELEY REFERENCES

CLARKEK. U. and LANGLEYP. A. (1963) Studies on the initiation of growth and moulting in Locmtu ~~~toriu ~~y~to~ioides R. & F.-+V. The relationship between the stomatogastric nervous system and neurosecretion. J. I~~sectPhysiol. 9, 423-430. CONRADI-LARSEN E-M. (1970) Influence of neurosecretion and nutrition on Oa-consumption in the bug, Oncopeltus fasciatus. J. Insect Physiol. 16, 471-482. DELPHIN F. (1963) Histology and possible functions of neurosecretory cells in the ventral ganglia of Schistocmca grega& For& Natwe, Lond. 200, 913-915. DOGRA G. S. and GILLOTT C. (1971) Neurosecretory activity and protease synthesis in relation to feeding in Melanomas sa~gui~ipes (Fab.). r. exp. Zool. 177, 41-49. EN~XLMANNF. (1968) Feeding and crop emptying in the cockroach Lmcophaea mkzderae. J. Insect Physiol. 14, 1525-1531. ENGELMANNF. and WILJXENSJ. L. (1969) Synthesis of digestive enzyme in the fleshfly Sarcophaga bullata stimulated by food. Nature, Lond. 222, 798. JARIAL M. S. and SCUDDERG. G. E. (1971) Neurosecretion and water balance in Celzoco&a bifi& (Hung.) (Hemiptera, Corixidae). Can. J. Zool. 49, 1369-l 375. KEELEY L. L. (1972) Biogenesis of mitochondria: neuroendocrine effects of the development of respiratory functions in fat body mitochondria of the cockroach, Blaberus discoidalis. Archs Biochem. Biophys. 153, 8-1.5. KEELEY L. L. (1974) Feeding effects on the neuroendocrine regulated development of fat body mitochondria in tbe cockroach Bhberus discoid&s. J. Insect Physiol. 20,1249-1255. KEELEY L. L. and FRIEDMANS. (1967) Corpus cardiacum as a metabolic regulator in Blaberus ~co~~is Serville (Blattidae)-1. Long-term effects of cardiacectomy on whole body and tissue respiration and trop.hic metabolism. Gela. camp. Endocr. 8, 129-134. MADDRELLS. H. P. (1963) Excretion in the blood-sucking bug Rhodnius prolixus Stal-I. The control of diuresis. 3. exp. Biol. 40, 247-256. MILLS R. R. and WHITEHEADD. L. (1970) Hormonal control of tanning in the American cockroach: changes in blood cell permeability during ecdysis. 3. Insect Physiol. 16, 331-340. MORDUEW. (1969) Hormonal control of Malpighian tube and rectal function in the desert locust, Schistocerca gregaria. J. Insect Physiol. 15, 273-285. SL.&A K. (1964) Hormonal control of respiratory metabolism during growth, reproduction, and diapause, in female adults of Pyrrhocoris upterus L. (Hemiptera). r. Insect Physiol, 10,283-303. THOMSENE. and MOLLER I. (1963) Influence of neurosecretory cells and of corpus allatum on intestinal proteinase activity in the adult Cu~~iphora ~ythroc~~~a. 3. exp, BioE. 40, 301-322. WALDSAU~IIG. P. (1968) The consumption and utilization of food by insects. Adv. Insect Physiol. 5, 229-288. WALKER P. A. (1965) The structure of the fat body in normal and starved cockroaches as seen with the electron microscope. J. Insect Physiol. 11, 1625-1631. WALL B. J. (1967) Evidence for antidiuretic controf of rectal water absorption in the cockroach Perip~~ne~ americana L. r. Insect PhysioZ. 13, 565-578. WALL B. J. and RALPH C. L. (1964) Evidence for hormonal regulation of Malpighian excretion in the insect, Periplaneta americana L. Gen. camp. Endocr. 4,452-456. WIGGLESWORTH V. B. (1934) The physiology of ecdysis in Rhodniusprolixus (Hemiptera)-II. Factors controlling moulting and metamorphosis. Quart. y. micr. Sci. 77, 191-222.