POPULATION DYNAMIOS AND MORPHOMETRY OF THE 1956 AND 1957 DESERT LOCUST POPULATIONS IN INDIA IN RELATION TO EYE -STRIPE COMPOSITION AND SEX-RATIOS By

IV-MoRPHOMETRIC CHARACTERS (SIZE OF BODY-PARTS) 1. General . . 2. Width of head at the ocular level (0) 3. Width of head at the genal level (C) 4. Length of pronotum at the keel (P) 5. Height of pro no tum at the pro zona (H) . 6. Width of pronotum at the constriction (M) 7. Length of elytron (E) 8. Restricted width of elytron (W1 ) 9. Length of hind-femur (F) 10. General conclusions regarding size of body-parts


General
The ninth (recorded) cycle of the Desert Locust Schistocerca gregaria (F orskal) (Orthoptera: Acrididae) in India started in the year 1949 and ended in 1955. The study of the population immediately succeeding this swarming cycle of 1949-1955 is of considerable biological interest, and may throw light on the processes of phase transformation. This is attempted here for the non-swarming population for the years 1956 and 1957 in India which are for convenience and because of small sample-size (n = 93) treated here together (also vide infra under Material and Methods).
It has been shown by  that the population of the last period (Group III) of the 1955-population was "dissocians" in nature. The 1956-57 population is compared with immediately preceding population (1955-Gr. III), and with other known populations in various degrees of phase-transformation, in order to ascertain its correct phase status.
The 1956-57 population is analysed in regard to size of body-parts, morphometric ratios, sex-ratios and eye-stripe composition.

History of the 1956-57 population
The specimens for the 1956-57 population were collected either singly from scattered populations or from thin concentrations. The populations remained fluctuating throughout the year. The maximum population density during the early period (January-April) in each year was 960 individuals per square mile. During the second period (May-August), the maximum population density was 5,040 per square mile, except for 'a few localities where the population became "countless" During the last or third period (November and December), no locusts were found, and the population was zero.

Abbreviation used
Except where otherwise stated, the following abbreviations have been used throughout:-

General
The material for the 1956-57 population was obtained mostly from contiguous localities in Rajasthan, Western, India. A total of 93 specimens were obtained (69 for the year 1956 and 24 for the year 1957).
The 93 individuals were collected from eight Districts of Rajasthan as follows:- Measurements: Morphometric measurements of eight body parts were made and were taken according to method laid down in Third International Locust Conference, London (1934); and as taken earlier by Roonwal et. al., (1945Roonwal et. al., ( , 1947Roonwal et. al., ( , 1949.

Statistical procedure
Technique: For comparison with "typical phases" and other previously studied populations, statistical comparison was made in respect of a number of morphometric characters and ratios. The common mean and dispersions (standard deviation), along with their standard errors, were computed as usual. The difference in mean values was tested for significance by expressing it as a ratio to the standard error of difference and referring the same to Normal Distribution table, if the sample size was fairly large. Where the sample-size was small and the hypotheses of equality of variances true as judged by Variance-Ratio Test, Student's t distribution was employed. In case of samples size being small but variances unequal, a more exact test procedure was adopted by finding a weighted average of level of significance for the two samples, the weights being the squares of standard errors of respective mean values. The level of significance was chosen at the 5 % point of probability, but the significance of difference was examined at 1 % and 0.1 % points also.
The populations were also compared by the graphical method.

Characteristics of 1956-57 population
The adult samples were randomly collected from a non-swarming periods of a short duration of two consecutive years. This period of two years have not been separately dealt with for two reasons: (i) They both belong to a similar populations ; and (ii) To increase the precision of statistical tests by including all the specimens in one sample. Classification of population of any year into seasonal groups, as was done in previous studies, was not made due to the non-availability of sufficient number of specimens in all the months. It is justifiably assumed that the dat'a are homogeneous and truly represent the field population.  (Table 1)

General
The sample size being small, the lumped population for the entire 1956-57 period was analysed, and the results are given below:- (Table 1) Only two types of specimens, the 6and 7eye-striped, were observed; the proportion of the two varying as follows:-  (Table 1) The sex-ratios among the 93 individuals were: Males 56 (60.20/0)' females 37 (39.8%).

Sex-ratios
The percentage of sex-ratios in relation to the eye-stripe categories varied thus:-Eye-stripes The eye-stripe composition and sex-ratio may now be discussed in relation to population and phases in the light of Roonwal's hypotheses (1945).

Records of the Zoological Surv~'Y of India
The 6-eye-striped individuals constitute less than BO% of the population (60±5 %) and indicate solitaria affinities. In the 6-striped category, the high proportion of males (75±6%), instead of 50% which is characteristic of phase gregaria, indicates solitaria affinities. In the 7-striped category, the predominance of females over males (~~ 62±8%: d'd'38±B%)  Abbre!Jiations: As in text. Only the more sensitive morphometric characters were studied, namely: 1. Width of head at the ocular level (0). 2. Width of head at the genal level (0). 3. Length of pro no tum at the keel (P). 4. Height of pronotum at the pro zona (H). 5. Width of pronotum at the constriction (M). 6. Length of elytron (E). 7. Restricted width of elytron (WI)' B. Length of hind-femur (F). Abbreviations : As in text.
(ii) 6-eye-striped (males and females) and 7-eye-striped (females only) individuals of the Initial or Kakko Concentration of 1949, i.e., the first year population of the 1949-55 Swarming cycle .
(iv) 6-eye-striped individuals of the Calcutta Swarm of 1961, i.e., the third year population of the 1959-63 swarming cycle ( Roonwal and Bhanotar 1962, and in Press).
(c) Inter-eye-stripe comparison ( Table 6): In both males and females, the value in 6-striped forms in significantly lower than in 7-stripes ones at all levels.
(d) Inter-population comparison (Table 7): Comparison was made with the 1955 .. Gr.III population (data given below); no comparison ·could be made with other population for want of data.

1955-population
In the 6-eye-striped category, the value is not significantly different from those in the 1955-Grs.I and III, but is higher than in the 1955-Gr.II at the 5 % level. No significant difference is noticed in the 7 -striped .  (Table 2): This varies as follows:-

(d) Inter-population comparison
6-striped females: The value is significantly lower than in 6-greg. and Cal.Sw. at all levels, but is not different from those in the Ajm.Sw., the Kakko Cone. and the 1955-Gr.III. Other populations (and eye-stripes)  In the 6-eye-striped category, the value in the 1956-57 population is significantly higher than in the 6-gerg .. and the 1955-Grs.1 and II, at all levels, but is not different from those in the 1955-Gr.111 and the Kakko Cone. No significant difference is noticed in the 7-eye-striped category.
(c) Inter-eye-stripe comparison ( Table 6): In both males and females, the value in 6-striped forms is significantly lower than in 7 -striped ones, a t all levels.

6-striped males:
The value in the 1956-57 population is not significantly different from those in 6-greg., the Ajm. Sw., the Kakko Cone. and the 1955-Gr.III, at all levels, but is significantly lower than in the Cal.Sw. at the 50% level only.
(c) Inter-eye-stripe comparison ( Table 6): In both males and females, the value in 6-striped forms is significantly lower than in 7-striped ones at all levels.
6-striped females: The value is not significantly different from that in 6-greg. and the 1955-Gr.III at all levels.
(c) Inter-eye-stripe comparison ( Table 6): In both males and females, the value in 6-striped forms is significantly lower than in 7-striped ones at all levels.
(d) Inter-population comparison ( 6-stri/1ed males: The value is significantly lower than In 6-greg. and the 1955-Gr.III at all levels.
6-striped females: The value is not significantly different from those in 6-greg. and the 1955-Gr.III at all levels. 7-striped males: The value is not significantly different from that in the 1955-Gr.III at all levels.

Sex (and eye-stripes)
Males (6) Males (7) Females (6) Females (7) This varies as follows:- (b) Inter-sex comparison ( Table 6) : In both the 6-and 7-eye-striped categories, the value in females is significantly higher than in the corresponding males at all levels.
(c) .Inter-eye-stripe comparison ( Table 6): In both males and females, the value in the 6-striped forms is significantly lower than in 7 -striped ones at all levels.
(d) Inter-population comparison ( 6-strif?ed females: The value is not significantly different from those in 6-greg., the Cal.Sw., the AJm.Sw., the 1955-Gr.III and the Kakko Cone., at all levels, but is significantly lower than in 6-sol. at the 5 % level.

7-striped males:
The value is not significantly different from those in 7-sol. and the 1955-Gr.III at all levels.
(c) In..ter-eye-stripe comparison ( Table 6): In males and females, the value in 6-striped forms is significantly lower than in 7-stripes ones at the 5 % and 0.1 % levels respectively. (Table 8)

6-striped females:
The value is not significantly different from that in the 1955-Gr.III at all levels.

-striped males and females:
In the corresponding sex the value is not significantly different from that in the 1955-Gr.III at all levels.

Sex (and e;ye-stripes)
Males (6) Males (7) Females (6) Females (7) Mean length ( (Table 6) : In both the 6-and 7-eye-striped categories, the values in females are significantly higher than in the corresponding males at all levels.
(c) Inter-eye-strifJe comparison (Table 6): In both males and females, the value in 6-striped forms is significantly lower than in the 7 -striped ones at all levels.

6-striped females:
The value is significantly higher than in 6-greg., the Cal.Sw., the Ajm.Sw., and the 1955-Gr.III at the 0.1 % level, but is not significantly different from that in 6-s01. and the Kakko Cone.
7-striped males: The value is significantly higher in 7-s01. and the 1955-Gr.III at 1 % level.

7-striped females:
The value is significantly higher than in 7-s01.
at the 5 % level only, but is not significantly different from those in the Other populations (and eye-stripes) 1955-Gr.I (6) 1955-Gr.II (6) 1955-Gr.III (6)  In the 6-striped category, the value is significantly higher than in 6-greg., the 1955-Q-rs.I and II, at the 0.1 %, 1 % and 0.1 % levels respectively, but is not significantly different from those in 6-s01., the Kakko Cong., and the 1955-Gr.III. No significant difference is seen in the 7 -striped categories.

General conclusions regarding size of body-parts
All the morphometric characters in the 1956-57 population demonstrate uniformly high degrees of differences between the sexes and the eye-stripe groups.
The four characters, namely, 0, H, M, and WI (the data for which were not available for "typical" solitaria population) were compared with the 1955-Group III, which is considered here as a close approximation to solitaria .
For the 1955-Gr.III, the 6-striped males (in all the above characters i.e., 0, H, M and WI) and the 7-striped females (in Hand Manly), show divergence, i.e., the mean values are significantly higher from the corresponding eye-stripe and sex-groups of the 1956-57 population. It may be pointed out that though both the populations are of the solitaria facies, one (1955-Gr.III) is heading towards it and the other (1956-57) has possibly attained that phase so that some difference between the two is to be expected. The values in the J956-57 population are nearer the typical ~olitaria than those of the 1955-Gr.III population.
Four other characters (C, P, E and F) were two utilized. Thus, for C, in the 6-striped males of the 1956-57 population, the value is significantly lower from gregaria population (viz., the "typical" gregaria, the Ajmer Swarm and the Calcutta Swarm) and from the 1955-Gr.III (solitariafacies) and the Kakko Cone. (1949). A significantly higher value in the 1956-57 population is noticed in P for females from those in gregaria populations, where as for males no significant difference is seen in this respect, except for the Calcutta Swarm (of 1961), where the value is significantly lower at the 5 % level. In respect of E, the value in 6-striped males in the 1956-57 population is significantly lower than in both gregaria (at all levels) and solitaria (at 5 % level) population~, 'except for the Kakko Cone. (of 1949). For 6-striped females, E in the 1956-57 population is not significantly different from gregaria populatiQris, but is significantly higher from phase solitaria at the 5 % level.
Regarding F, the 6-striped categories in both sexes have significantly higher values than the gregaria populations and the Kakko Cone., but are not significantly different from the "typical" solitaria and other solitaria facies populations (1955-Gr.III). In 7-striped females, _ the 1956-57 population retains its affinity to phase solitaria by not being different from the I955-Gr.III(7) and the Kakko Conc.(7). However, in males, the value is significantly higher than in phase solitaria(7) and the I955-Gr.III (7).

Elytron Ratio (E/W 1 ) 5. Elytron-Femur Ratio (ElF) 6. Elytron-Head Ratio (E/C) 7. Femur-Head Ratio (F/C)
The mean values of these ratios were calculated separately for each individual and then a single mean was derived collectively.

(b) Inter-sex comparison
The value in females is significantly higher than in males at the 5 % level only.
(c) Inter-eye-stripe comparison ( Table 6): In both sexes the value in the 6-striped category is not significantly different from that in the corresponding 7 -striped one at all levels.
(d) Inter-population comparison ( Table 9): The 1956-57 population compare with the other populations (data given below) as follows:-
O.87±0.005 0.87±O.013 0.89±0.009 0.89±0.007 Records oj the Zoological Survey oj India (b) Inter-sex comparison ( Table 6) : In both 6-and 7 -striped categories, the values in females are not significantly different from those in corresponding males at all levels.
(c) Inter-eye-stripe comparison ( Table 6): Within each sex-gro~p, the value in the 6-eye-striped category is not significantly different from that in the 7-striped one all levels.
6-striped females: The value is significantly higher than in 6-greg. at all levels, but is not significantly different from that in the 1955-Gr.III.
7-striped males: The value is not significantly different than in the 1955-Gr.III at all levels.
7-striped females: The value is significantly lower than in the 1955-Gr.III at all levels. In the 6-and 7-eye-striped categories, the value is significantly lower than in the 1955-Gr.I(6) and the 1955-Gr. III (7), but is not significantly different from other populations.
(c) Inter-eye-stripe comparison ( Table 6): In either sex, the value in 6-stl'iped individuals is not significantly different from that in the corresponding 7 -striped ones at all levels.

6-striped females:
The value is significantly higher than in 6-greg. at all levels, but is not significantly different from that in the 1955-Gr.III.

7-striped males and females:
The value is signifiGantly lower than in the 1955-Gr.III at the 5 % level in males and at all levels in females.  (Table 4): This varies as follows:-
(c) Inter-eye-stripe comparison ( Table 6): _ In both sexes, within each sex-group, the values in the 6-striped categories are not significantly different from those in the corresponding 7 -striped ones at all levels.
(c) Inter-eye-stripes comparison ( Table 6): The value in 6-striped i;ndividuals is significantly higher than in 7 -striped ones (at the 5 % level only) in males, but is not significantly different in females. .

6-striped males and females:
In both sexes, the values are significantly lower than those in corresponding sex in the 6-greg., the Cal.Sw., the Ajm.Sw., the Kakko Conc., the 6-sol. and the 1955-Gr.III at all~levels.

7-striped males:
The value is significantly lower than in 7-sol. and the 1955-Gr.III at the I % level.
3.98±0.02l 4.02±O.038 4.05±0.024 4.11 ±0.033 (b) Inter-sex comparison ( Table 6): In 6-striped forms the value in females is significantly higher than in males at the 5 % level only, but in 7 -striped ones there is not significant difference between the sexes at all levels.
(c) Inter-eye-stripe comparison ( Table 6): In both sexes, the value in 6-striped individuals is not significantly different from that in the corresponding 7-striped ones at all levels.

General conclusions regarding ratios
Within the 1956-57 population, with the exception of a few ratios, the sexual and eye-stripe differences remain invariant. .
In respect of the ratio P 10, the 6-striped males and females in the 1956-57 population have significantly higher ratios than those in populations of the typical gregaria facies, the 1955-Gr.III(6) and the Kakko Cone. (1949) (the latter two populations tending towards phase solitaria but not quite attaining the stage). Regarding the ratios MIG and HIC, significantly higher values are recorded in the 1956-57 population than in typical gregaria for both sexes, but the difference from the 1955-Gr.III(6) population is not so marked, particularly in females.
The ratio E/W 1 does not show any appreciable difference from the 1955-Gr.III(6) population. It is interesting to note that the ratio ElF shows significantly lower values in the 1956-57 population than in both the "typical" phases gregaria and solitaria. Since it has attained values even lower than in phase solitaria, the solitaria nature of this ratio may not be doubted. Values for the ratio E/G are available only for the 1965-Gr.III and a comparison of the 1956-57 population with it does not reveal any difference of note.
Regarding the ratio FIG, considered now as the most sensitive ratio, the 1956-57 population differs from the typical gregaria population to a great extent and is almost identical with the typical solitaria populations.

VI-DISCUSSION AND CONCLUSIONS
We may now summarise some general conclusions regarding the phase status of the 1956-57 population.

i5
With respect to the composition of eye-stripes and sex-ratios, the 1956-57 population reveals, in general, its similarity with the "typical" phase solitaria and other solitariform populations.
The nearly equal percentages of the sex-ratios (d' 50: ~ 50) in the 6-eye-striped individuals, which is a condition usually associated with gregaria populations (RoonwaPs Hypotheses, 1945), is here ~omp]etely disturbed. Sex-ratio in 6-striped individuals is d' 75 ±6: 25±6. In the 7-striped category, females predominate (0 38±8 % : ~ 62±80/ o ), thereby further indicating the solitaria nature of the population. The same nature is shown by the eye-stripes proportions; a shrinking in the number of 6-eye-striped individuals to under 800/0, and a relative abundunce of the 7 -striped individuals, characters which show the solitaria nature of the population.
In 6-striped males, the characters P, E and F show their closeness to the solitaria condition. The character 0, C and W l though differing from solitaria values, do so to a small extent only. Only characters Hand M differ considerably from the solitaria values. In 6-striped females, the characters 0, C, H, M, E, W l and F have values close to typical solitaria ones; but character P shows significant difference at the 5 % level. In the 7 -striped category, in both males and females, all the characters, except F in males, show their close affinity with the Jolitaria condition.
With respect to ratios, in 6-striped m~les, E/W 1 and EIC show no difference from the solitaria condition, but ratios PIC and H/C differ to a small extent. The ratio ElF is smaller than the typical values for both phases. F/C has values closer to solitaria. Only the ratio MIC ~oes not indicate any definite affinity to either of the phases. In 6-striped females, the ratios MIO, HIC, E/W 1 and EIO have values similar to those in the typical solitaria populations. In the ratios PIe and FlO, the difference is less pronounced from the typical solitaria than from the typical gregaria. The ratio ElF differs from the typical values in both the phases, but is closer to the solitaria.
In 7-striped males, PIC, MIG, E/W 1 and E/C do not show any difference from the solitaria values, but the other ratios have values which are either significantly lower (H/C and ElF for both sexes) or higher (F IC for males only) from those in typical solitaria populations. In 7-striped females, PIC, E/W 1 , EIC and FIC have values as in phase solitaria. The remaining ratios do not indicate any definite affinity to either of the phases.
Thus we may say that while generally, the 1956 . . . 57 population shows affinity to the solitaria phase, in some respect it behaves in a peculiar way. Females have been found to be more phase sensitive than males, the latter, in many characters, retaining a gregaria or a near gregaria characteristic.
VII-SUMMARY 1. A random sample of 93 individuals of a Desert Locust population in Rajasthan, weste~ India, obtanied durin~ the non-swarming