Volume 92, Issue 6
November 1983, pages 409-481
pp 409-414 November 1983
Studies on the inheritance of resistance to malathion in an originally field collected malathion-resistant strain ofT. castaneum by making genetic crosses between the resistant and a susceptible strain revealed that resistance in this strain is controlled by an autosomally inherited single major gene which is incompletely dominant.
pp 415-422 November 1983
The seasonal condition (K) and relative condition (Kn) cycles and their changes with the growth of the fishChanda commersonii (Cuv. and Val.) for 2 yrs are presented. BetterK is shown by the smaller immature and first maturity stages and larger, almost senile groups but they show aKn factor below ‘1’. The actively breeding adults show a uniform fail inK but they give comparatively highKn values (above ‘1’). These changes inK andKn with the growth of the fish are clearly reflected in their seasonal cycles also.K cycle would thus appear to follow a pattern of build up and loss of body resources, indirectly following the breeding cycle while theKn cycle follow the breeding and feeding cycles directly, as shown by their seasonal changes and changes with growth of the fish for 2 yrs. Since only minor deviations from unity occur inKn factor it furnishes a more sensitive index of somatic difference between age groups, of breeding season and feeding cycle.
pp 423-428 November 1983
The Indian gerbil,Tatera indica indica Hardwicke, bathes by alternately rubbing its flanks (side-rubs) in the substrate, such as sand. Bathing frequencies are ordinarily low; but significant increments follow modifications made in pelage condition. When these are asymmetrical, more actions are directed towards the treated than the untreated side. Evidently, peripheral input regulates the behaviour.
pp 429-435 November 1983
Tropical spidersC. cicatrosa andM. calcutaensis were allowed to predate individually in different terraria at different prey densities. Both the species were satiated within 5 hr of predation in all the volumes. Prey density exerted significant influence on the predatory behaviour of both the species. The predation increased with increasing prey density, but the volume of terraria exerted only marginal influence. The functional response curve ofC. cicatrosa andM. calcutaensis was neither linear nor sigmoid, but was curvilinear representing type II response of Holling’s model.
pp 437-446 November 1983
The population dynamics and energy budgets of two grasshopper speciesTristria pulvinata Uvarov andPhlaeoba infumata Brunn were studied in a grassland at Kurukshetra. Males outnumber females. The aboveground net primary production was more in stand I as compared to that in stand II. Mean secondary production was 753.88 mg m−2. Field population of the grasshopper species consumed 308.57 K cal m−2 during the study period.
pp 447-452 November 1983
Population dynamics and biornass of aboveground insects were studied in a tropical grassland. A total of 30 species belonging to five insect orders viz., Odonata, Mantoidea, Blattoidea, Neuroptera and Diptera were collected. Maximum population density and biornass values on stands I and II were determined.
pp 453-466 November 1983
The paper deals with the findings on some aspect of ecology ofSchizodactylus monstrosus Drury. Studies on vertical distribution showed that the highest total density was in the 0 to 20 cm depth. Maximum concentration of the species was found in the first horizontal row. Monthly population structure on vertical distribution was also studied. Statistical analysis showed a significant correlation between the relative humidity and the distribution. Biomass of both the sexes and nymphal populated was estimated.
pp 467-473 November 1983
Meloidogyne incognita (Kofoid and White 1919) Chitwood 1949 was found to complete its life cycle within the roots of the banana plantMusa paradisiaca (cultivar Palayathodan). Egg sacs were confined entirely within the root. Second stage larvae penetrated the endodermis and on entering the stele succeeded in inducing multinucleate giant cells which were solely confined to the stele and never found in the cortex, induction of giant cells and production of large number of females in banana roots showed that this is a susceptible host plant. Heavily infested roots showed histopathological changes which could lead to the blockage of conducting elements. This nematode is not very common in banana roots probably because second stage larvae emerging from the egg sacs reinfested the same roots and also because of the differential susceptibility of the various cultivars of the banana plant.
pp 475-481 November 1983
Sublethal concentrations of DDT and methyl parathion (MP) in the medium significantly affected the rates of feeding, absorption and conversion inChanna striatus. Fish exposed to 250 ppb DDT or MP consumed 23 or 50% less food than those exposed to pesticide-free water. Correspondingly, absorption rate also decreased from 120 cal/g live fish/day in the control to 88 and 59 cal/g/day in those exposed to 250 ppb DDT and MP. Efficiency to convert the absorbed food into body substance dropped from 30% in the control to 6 and 12% in the 250 ppb DDT and MP groups. Metabolic rate of the control averaged to 84 cal/g/day; whereas exposure to DDT did not significantly affect the metabolic rate, a concentration of 250 ppb MP depressed the rate to 52 cal/g/day.