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Activity patterns and body temperature (Tb) and its maintenance were investigated in the 5th instar larvae of Antheraea assama Westwood (Lepidoptera: Saturniidae). These larvae thermoregulate by finding and utilizing favourable microenvironments and by restricting their activities to suitable times of the day. Further convective cooling, facilitated by a raised posture also serves to ameliorate Tb. Regression analysis suggests that environmental temperature is the major determinant of Tb along with solar radiation (SR) and wind (W).

In the current study, a dimeric phenoloxidase (PO) from the hemolymph of healthy and diseased (pebrine infected) larvae of Antheraea assamensis Helfer was extracted and purified. The protein was subjected to purification using Sephacryl S-100 and CM Sepharose chromatography. The enzyme comprised of two subunits of~76.8 and 76 kDa that showed PO activity in 6 mM L-3,4-dihydroxyphenylalanine (L-DOPA) and 8 mM catechol but not in hydroquinone. Optimum temperature for PO activity was 30°C in L-DOPA and 37°C in catechol. Optimum pH ranged from 6.8 to 7.0 in L-DOPA and 7.0-7.2 in catechol. Specific activity of the purified PO from healthy larvae was 53.9 µM/min per mg of protein per ml in L-DOPA and 50.77 µM/min per mg of protein per ml in catechol. Specific activity of PO from diseased larvae was 30.0 µM/min per mg of protein per ml in L-DOPA and 28.55 µM/min per mg of protein per ml in catechol. Purification fold was 3.27-4.21 for healthy and 2.38-2.56 for diseased fractions. The enzyme showed the Michaelis constant (K m ) of 2.46-2.85 mM for healthy and diseased fractions in L-DOPA. In catechol K m of 9.23-17.71 mM was observed. Peptidoglycan was the best activator of purified PO from both healthy and diseased fractions. Interactions between controls Arch. Insect Biochem. Physiol. 2019;100:e21531.wileyonlinelibrary.com/journal/arch

Differential hemocyte count of circulating plasmatocytes (PL) and granulocytes (GR) of fifth-instar larvae of Muga Silkworm Antheraea assama Westwood (Lepidoptera: Saturniidae) reared at four different sericulture farms situated at different altitudes, viz, Khanapara State Sericulture Farm, Assam, altitude 55.5 m above sea level (ASL); Nongpoh (Central Silk Board farm), Meghalaya, altitude 464 m ASL; Tura (Central Silk Board farm), West Garo Hills, Meghalaya, 657 m ASL; and Kalimpong (Central Silk Board farm), West Bengal, altitude 1,247 m ASL, were calculated and compared to investigate the effect of altitude on the number of PL and GR per mm3 of larval hemolymph. The investigation showed that the mean circulating PL and GR were highest at Khanapara (55.5 m ASL) located at the lowest altitude, whereas their numbers gradually decreased with increase in altitude at Nongpoh (464 m ASL), Tura (657 m ASL), and Kalimpong (1,247 m ASL). This may be attributed to the average environmental temperatures observed at different altitudes, which may affect the overall hemocyte load of larval stages reared at those altitudes.