The eggs were found to be laid and deposited in clusters in a silken pouch. In some cases, the egg pouches were observed to be connected to the posterior side of the dead females below the surface of soil. The female laid usually 85-135 eggs. The laying period continued for about 20-25 days. Initially, the eggs were highly pinkish and later turn reddish brown in color.
The eggs laid earlier in the previous season were noted to be available up to a depth of 20 cm in the soil around the mango trees in the experimental orchard. This behavior coupled with observations recording hatching of eggs and time of laying from end of May to June suggests that the insect remains in diapause, in egg stage, from June to early late December.
Adult longevity of females and males:
The longevity of adult females varies from 46-48 days with an average of 46.3 ±3.4 days and that of males varies from 5-8 days with an average of 6.9±1.41 days (Table 10). The females lived much longer life which was six times more than the longevity period of males. The nymphs of both the sexes were seen to become most active in their looks and behavior after entering the second stage of their development following their first moulting.
Total life cycle:
Female mealy bug completes its total life from hatching of eggs to death within 107-180 days and males in 64-117 days (Table 10).BioEcological studies.
This section deals with the bioecological studies of some important insect pests recorded from the area under present study. The study not only includes biology and life cycle of the pets but also its ecological aspects.
The insects investigated in detail are Drosicha mangifera, Dichocrocis punctiferalis, Bactocera dorsalis, Spodoptera litura and Euthalia aconthea.
Drosicha mangifera Green, 1903
Scanning of the earlier literature revealed that biology of Drosicha mangifera Green, 1903 has been analyzed by Raina (1994). Bhau (2012) also studied the biology of mango mealy bug on mango.
The males fly where the females are presents. The winged male soon after emergence mates with the apterous female. Though the female mates only once but the male fertilizes with more than one female. Male climbs over the female. The mated female descends the tree and reaches the soil for oviposition. Mating time of males vary and were ranged from 6.00 to 20.50 minute.
Drosicha mangiferae Green has one generation each year. Gravid females laid about 80-135 eggs with an average of 104±19.81 eggs in clusters within a cottony pouch just below the surface of the soil taking about 20 days for completion of oviposition. The cottony cushion was secreted by the female bug before laying of eggs. After this the female laid eggs within the cushion. Chandra et al. (1987) have reported that a female lays 300 eggs while Raina (1994) reported 120-140 eggs per female. On the contrary to the present finding, Singh et al. (2015) who reported that 145 to 418 eggs laid by the female bug. Observations of present author here also support earlier recorded observations of Bhau et al. (2017) who reported the mean no. of eggs laid by the female were 85-135 with an average of 22.70±122.2.
The mature female bug laid eggs in an egg case of cushiony white wax, generally in clusters. The freshly and the newly laid eggs are oval in shape and shining pink in color but later on its color gradually changes to yellow. The eggs are laid in the soil around the infested mango trees. Eggs hatch in December–January after diapausing in ovisacs in the soil or the duff around the host. The nymphs start climbing the trees so as to reach to succulent shoots and the footing of fruiting parts. The mean length of egg measured 1-3 mm with an average of 1.8 ±0.36 mm and width of 0.1-1 mm with an average of 0.72±0.3 mm (Table 9). Raina (1994) recorded average length of 1.22 and width of 0.74 mm. Bhau (2012) recorded more or less similar observation of egg length of 1.9 mm and width of 0.7 mm.
Nymphs come out from the ovisacs and mostly started settling along midribs and veins on the underside of leaves, young twigs and fruits. The nymphs of both sexes i.e males and females resemble the female adults in appearance. In females there are three nymphal instars and in males four are found. The male’s last instar posse’s wing buds within a coccon of mealy wax and is considered as the most inactive stage of the life cycle.
The first instar nymphs are reddish to brown in colour, oval-shaped with red eyes. Later on the nymphs were enclosed with whitish powder. After some days, a streak emerged longitudinally over the head side of the nymphs and the second instar nymph comes out but remained half in the exiuvae. The nymphs shed the exiuvae and again started feeding. The first instar female and male nymph measured 1- 2mm with an average of 1.4± 0.40mm and width of 0.2- 2mm with an average of 0.65 ±0.35mm (Table 9). Raina (1994) recorded average length of 1.06 and width of 0.67mm. Bhau (2012) recorded more or less similar observation of first instar female and male nymph length of 1.3mm and width of 0.7mm.
First nymphal instar male and female lasted for 44- 68 days with an average of 53.1± 4.48 days (Table 2). Raina (1994) recorded average duration of 55.1±4.58. Bhau (2012) recorded more or less similar observation of first instar female and male nymph average duration of 51.1±2.64.
The second instar nymphs are highly whitish and oval-shaped. The second instar female and male nymph measured 1-4 mm with an average of 2.7±1.6 mm and width of 1-3mm with an average of 2.1±0.4 mm (Table 9). Raina (1994) recorded average length of 1.06 mm and width of 0.67mm. Bhau (2012) recorded length of 1.3mm and width of 0.7mm. Second nymphal instar male and female lasted for 19-35 days with an average of 30.2±7.20 days (Table 10). Raina (1994) recorded average duration of 30.50±7.50. Bhau (2012) recorded an average duration of 22.7±2.08 days. A streak appeared over the head side longitudinally and nymphs crawled out but remained half in exiuvae. After 30 days, the nymphs shed exiuvae and again started their feeding. All the nymphs shed their exiuvae within 26 days.
Third instar female:
The third instar nymphs are reddish, oval-shaped. The third instar female measured 2-4mm with an average of 4.1±1.6 mm and width of 2-4mm with an average of 2.0±0.7mm (Table 9). Raina (1994) recorded average length of 1.06 mm and width of 0.67mm. Bhau (2012) recorded length of 1.3mm and width of 0.7mm.
Third nymphal instar female lasted for 11-40 days with an average of 34.1±9.06 (Table 10). Raina (1994) recorded average duration of 35.0±10.06. Bhau (2012) recorded an average duration of 32.9±1.15.
Third instar male:
The third instar represents prepupal stage of the male bug. The male remained sluggish and started preparing a cocoon in its later stage which finally forms the coccon representing its pupal stage. It measured 2-4mm with an average of 4.1±1.6 mm and width of 2-4mm with an average of 2.0±0.7mm (Table 9). Raina (1994) recorded average length of 1.06 and width of 0.67mm. Bhau (2012) recorded length of 1.3mm and width of 0.7mm. The duration of prepupal period recorded as 4-8 days with an average of 6.2 ±1.22 and and pupal stage as 5-9 days with an average of 6.1 ±1.00 (Table 10). Similar observation was made by Raina (1994) as prepupal and pupal average duration is 6.4±1.42 and 5.9±1.19. Bhau (2012) recorded prepupal and pupal an average duration of 6.08±0.58 and 6.1±1.00.
Adult female and male:
The adult female was wingless with a flattened body covered with white mealy powder while the adult males are delicate having a beautiful crimson red body, a pair of brownish – black wings and long antennae. Legs large and conspicuous; antennae large, 7 to 11-segmented; claw digitules not reaching tip of claw, usually not enlarged apically; not forming a cyst. The adult female measures 6-10mm with an average of 4.75 ±1.8 mm and width of 2-5mm with an average of 1.5± 0.5mm (Table 9). The adult male measures 4.5-8 mm with an average length of 4.5± 1.7 and width of 2-4.5mm with an average of 1.3± 0.5mm (Table 10). Bhau (2012) has recorded more or less similar observations.