Determination of critical threshold for induction and termination of diapause (hibernation) are important for better understanding the bio-ecology and population dynamics of Chilo partellus (Swinhoe) under varying climatic conditions. We studied initiation and termination of hibernation under five temperature and photoperiod regimes viz., 27°C + 12L:12D, 22°C + 11.5L:12.5D, 18°C + 11L:13D, 14°C + 10.5L:13.5D and 10°C + 10L:14D under fixed and ramping treatments, and the observations were recorded on various phenological and developmental characteristics at weekly intervals. Present studies revealed that the induction of hibernation in C. partellus larvae takes from 46 to 56 days depending upon temperature and photoperiod conditions. Induction of hibernation varied from 7.9 to 18.3% across treatment conditions, indicating that not all C. partellus larvae undergo diapause under prevailing environmental conditions. Weight, length and head capsule width of diapausing larvae were found significantly lower than the non-diapausing larvae. The non-diapausing C. partellus larvae required a thermal threshold of 1068 degree-days under ambient conditions, while in case of hibernating larvae it varied significantly across treatment conditions. Diapausing larvae underwent up to five supernumerary moults, wherein highest percentage of diapausing larvae (35.7%) exhibited two supernumerary moults. The developmental time of diapausing larvae varied from 94.9 to 160.4 days across treatments. A population loss of 17.2-28.3% was recorded in C. partellus due to hibernation, which has implications for population buildup of post-hibernation first brood and management strategies.

Diapause is an important adaptive trait in certain groups of insects at a particular stage, which contribute in controlling insect ecology, phenology, and physiology. Considering the importance of various factors in appropriate combinations, we studied effects of different temperature and photoperiod conditions on larval morphometrics, development, induction, and termination of estivation, and overall mortality due to estivation in Chilo partellus (Swinhoe). Weight, length, and head capsule width of C. partellus larvae significantly increased with increase in temperature and photoperiod treatments upto certain age and duration of exposure. According to Dyar's ratio, overall head capsule width progressed geometrically with minimum constant ratio of 1.20, and second‐degree polynomial regression equations were best fitted to all the test treatment conditions. The mortality of diapausing C. partellus individuals varied between 7.0% and 37.3% under different constant and varying temperature and photoperiod regimes, which at 38°C + 14L:10D reached upto 100.0%. However, the exposure to 30°C + 12.5L:11.5D and 32°C + 13L:11D along with dry food accelerated the process of estivation, wherein the diapause larval survival was significantly higher and overall mortality of individuals due to diapause was lower suggesting these conditions appropriate for induction of estivation in C. partellus. These studies have implications for better understanding the bioecology and population regulation system under varying climatic conditions and devising novel strategies for management of C. partellus.

Zygogramma bicolorata Pallister is a potential biocontrol agent of Parthenium hysterophorus L. (Asteraceae). This study was carried out to understand the effect of abiotic (temperature and moisture) and biotic factors (age and reproductive status) on the induction and termination of diapause in Z. bicolorata. We also evaluated the effect of diapause on longevity and fecundity of Z. bicolorata. In Z. bicolorata the induction of diapause occurred between the months of July and December. No diapause was observed in May and June, which coincided with the commencement of the monsoon rains. The percentage of diapause induction in Z. bicolorata was found to increase from one generation to another as well as with the age of adults. Diapause significantly increased the fecundity of females as compared to the fecundity in pre-diapause conditions. Soil moisture (80% RH) played an important role in providing the conditions for initiation and termination of diapause. Similarly, 18.4 and 12.5% of diapause adults resumed their activity in 6 and 5 days when exposed to temperatures of 40° and 45° C for 2 h every day, respectively. Exposure of adults to low temperatures, i.e. 5° and 10° C induced 94.3 and 92.5% diapause, respectively, with no adult mortality. Thus, our findings reveal suitable conditions for preventing and inducing diapause in Z. bicolorata, which is of great importance in the suppression of P. hysterophorus. We discuss the implications of these findings in the control of P. hysterophorus.

Geographic distance and ecological conditions are important factors for phenological differentiation, and the adult morphological characters play significant role in several biological functions in insects. Present study showed significant intraspecific and intersex variation in colour pattern, number of spots and stripes on the forewings of Chilo partellus adults of different ecological populations. Females were comparatively light in colour with less black spots and stripes than the males across populations. Length and width of head, thorax and abdomen, wingspan, and various parts of male and female genitalia varied significantly across C. partellus populations. Abdomen, corpus bursae and papillae anales were significantly longer in females of Hisar as compared to other populations. However, the length of aedeagus was significantly longer in males of Coimbatore and Delhi as compared to other populations. Range of wingspan: body size and body size: genitalia ratios across C. partellus populations were wider in females than males. Wingspan: body size ratio was significantly lower in males of Raichur and females of Hisar and Parbhani as compared to other populations. Body size: genitalia ratio was significantly lower in males of Coimbatore and Hyderabad, and females of Coimbatore, Raichur and Surat as compared to other ecological populations. These findings suggest phenotypic plasticity in C. partellus having implications for phenotypic expression and greater fitness in response to changing climatic conditions.

Entomological survey was conducted at Kandla international seaport, Kandla, Gujarat, India during pre-monsoon season of 2018 for immature Aedes mosquitoes. Standard entomological techniques were used for survey. All approachable larval breeding habitats were inspected. Inside seaport area, a total of 45 premises were searched for Aedes breeding out of which 02 premises were found inside area of seaport with 4.44 Premises Index (PI), 1.77 Container Index (CI) and 4.44 Breteau Index (BI). Out-side area of seaport (non-residential), none of premises/ containers were found positive for breeding while in out-side residential area 27 were searched out of which 02 houses were found positive for Aedes breeding with 7.4 House Index (HI), 8.10 Container Index (CI) and 11.11 Breteau Index (BI). Intermittent supply of water was the main reason for Aedes breeding in residential colony. From this study it is evident that inside port area and outside port area provided ample habitats for the mosquitoes to breed and thrive in wet season. Regular entomological surveillance is needed not only to monitor the Aedesmosquito breeding in and around port area including residential areas nearby but also to prevent the transportation and establishment of mosquito species in newer areas. Community awareness is also equally important to prevent entry of vector mosquito species in new areas.