Significance of critical developmental stage on starvation induced endocrine mediated precocious metamorphosis inOryctes rhinoceros (Coleoptera: Scarabaeidae)

Proc. Indian Acad. Sci. (Anim. Sci.)

1988

Self Cite

Protease, amylase, lipase and trehalase are present in the larval and adult mid guts of Oryctes rhinoceros; cellulase is absent. Invertase is present only in the adult. The presence of trehalase in the pupal midgut suggests that food digestion is not the normal function of gut trehalase. Quantitative studies reveal that protease and amylase in the third instar larvae reach very low levels as the larvae become older and consume little or no food. These two enzymes are not measurable in the non-feeding prepupa and pupa and reappear in the adult with commencement of feeding. Secretion of digestive enzymes is correlated with feeding.

Section: Methodsmentioning

confidence: 99%

Digestive enzyme secretion during metamorphosis inOryctes rhinoceros (Coleoptera: Scarabaeidae)

Sreekumar

Proc. Indian Acad. Sci. (Anim. Sci.)

1988

Self Cite

“…Third (final) instar larvae of O. rhinoceros reared in the stock colony as described by Mini and Prabhu (1986) but on sterilised cowdung, were used for the study.…”

Section: Methodsmentioning

confidence: 99%

Probable endocrine role of midgut tissue in stimulation of digestive enzyme secretion inOryctes rhinoceros (Coleoptera: Scarabaeidae)

Sreekumar

Proc. Indian Acad. Sci. (Anim. Sci.)

1988

Self Cite

The effect of midgut epithelial extract on digestive enzyme secretion in the third instar larva of Oryctes rhinoceros was studied. Midguts dissected out from third instar larvae were cut at both ends, emptied of their contents, washed in insect saline, ligated at the open ends and incubated in a medium containing extract of 2 midgut epithelia/lO ml incubation solution. In control experiments midgut preparations were incubated in insect saline without midgut epithelial extract. After 30 min of incubation, the contents of the midgut preparations incubated with midgut epithelial extract showed increased secretion of protease and amylase when compared with controls. Digestive enzyme release into gut lumen appears to be due to the action of a hormone present in the midgut epithelium.

Stridulation in the coconut rhinoceros beetleOryctes rhinoceros (Coleoptera: Scarabaeidae)

Mini

1990

Proc Ani Sci

Self Cite

Ahstract. The coconut rhinoceros beetle Orycres rhinoceros produces different kinds of stridulatory sound under different conditions. Intense stridulations are made quite frequently by the male during courtship and mating attempts. Males also produce characteristic stridulations during aggressive encounters with other beetles, and distress stridulations, when disturbed manually. Females also stridulate, though less frequently. Sexually immature females produce feeble repellence stridulations while courted by males. Gravid females, when confined with males, are found to mimic the courtship and mating behaviour of the males, meanwhile producing intense stridulations resembling male courtship and mating stridulation. This behaviour, presumably has an ovipository motive and. to our knowledge, is the first instance of 'pseudomale' activity to be reported in insects.Stridulatory mechanism comprises rubbing of a specialised region along the margin of the apex of the elytron -the pars stridens, against a series of striations -the plectrum, occupying the dorsum of the 7th abdominal tergite, Stridulation is possible with a single pars stridens, either of the left or right elytron, both being identical. No sexually dimorphic difference is apparent in the pars stridens. Plectral structure exhibits sexual dimorphism, being much prominent in the male.Wing-locking is necessary to keep the elytra in the stridulatory position. locking is elTected by a longitudinal flange along the median side of one elytron (either the left or right, irrespective of the sex) fitting into a corresponding depression along the other. This differs from the reported cases in other coleopterans in which the flange of the left elytron extends under the right when locked.