Life cycle of Rhabditis sp.
Life cycles differ depending upon the species of nematode. life cycle is summarized in( Fig.1). Thenematode parasite (Rhabditis sp.) infected earthworms (Allolobophora caliginosa) (Fig.2,A), but only in its larval stage(Secondstage), encapsulated in the body wall or in the coelom were mostly activejuveniles or infective stage, whereasothers were able to encapsulated and incorporatedinto “brown bodies ” in the earthworm coelom (Fig.
2,B),and thisencapsulation process is an effective defense reaction(Fig.2,C). Rhabditislarvae found in earthworm (Fig.2,D)develop only when the earthworm dies andcomplete the life cycle in soil. Dead earthworm were completely decomposed,with only a faint outline remaining.
When “brown bodies” thatrepresents spherical masses of host cells surrounding parasites and containingliving nematodes were placed on nutrient agar, only a few nematodes escaped,and cultures were rarely established. no sign of inflammation in the earthworm was noted. All of the 585 specimensof (Allolobophora caliginosa) which were collected contained 151 of Rhabditissp. Larvae begin feeding on thebacteria in soil that the tissues losses from 5 days to weeks days. of Mostly died after lay theeggs .Fourth stage larvae of Rhabditis sp. Appeare in two shapes femalesmore than males (from week to 10 days ). Adult Rhabditis sp.
lay eggsafter 10 -15 days. Once formed, first and second stages the infective Rhabditissp. will continue their development, onfresh box cultivated with bacteria.
These nematodes will continue their life cycle by finding the earthworm and penetratethe earthworm’s pores and cocoons’ host.Infective larvae of Rhabditis sp. were able to persist in the soilwith lack of food up to 4 weeks, thus increasing their chance to meet a host. In theearthworm’s host developed to third stage in life cycle.
Description of Rhabditis sp. ( Based on 10 males and 10 females )Light microscopically study:stage larvae of Rhabditis sp., (Fig.4,L)were collected from the anterior of the coelom of living earthwormhost(Fig.2,D). Adult Rhabditis sp., male(Fig.4,A)and female (Fig.
4, E) werecollected from a culture as free living nematode ,151 out 585 Allolobophora caliginosa were infected andprevalence of infection was 25.81% , males 52 out 151 and prevalence ofinfection was 34.43% and females 99 out 151 and prevalence of infection was 65.56%.The excretory pore is below the level of the esophageal bulb ,the esophagusends in valvulate, sub-spherical bulb which is separated from esophageal bodyby small constriction ,the posterior part of tail is elongated, smooth and forma thin needle-like projection (Fig. 3).Scanning Electron Microscopically study:Male: SEM micrographs show that the males (Fig.
4,B) Body cylindrical and colorare creamy white ,small and cylindrical in shape, Cuticle thick(Fig.4,J) is 4 – 6 µm (av.=5) µm, bearing a pattern oftiny dots arranged transversely and longitudinally rows. the body length is 1750 -1850µm (av.=1800)and the width is 210-190µm (av.200). Theesophagus is cylindrical and the length (including bulb) is 290-270 µm (av.
=280). The alae are well expanded near the posteriorend of body .Two lateral cuticle alae extending along body, interiorly initiating slightly in front of nerve ringlevel and posterioly reaching to cloacae. The alae reached 30-50µm in width and 100-150 µm in length. the distance of excretory pore from theanterior end is 540-650 µm(av.=595) . Nerve ring is 300 – 380 µm (av.=340).
Filiformtail conical-elongate (Fig.4,D) extends 302-279µm (av.=291)beyond postcloacal papillae and no specula is present . There arethree pairs of genital papillae, not all included in caudal alae. The first pair of papillae is preanal andformed by small sessile papillae.
The second one is the first of the post analpairs and situated near the posterior border of caudal alae. The second postanal pair is formed by a largepedunculated papillae and situated immediately below foregoing pair.Female: The female (Fig.4,F) is larger thanmale, the length of gravid females is 2800-2000 µm (av.=2400) and the maximumwidth is 370-400 µm (av.= 385).
The mouth is surrounded with six lips(Fig.4,C).The length of esophagus(including bulb) is 450-350 µm (av.
=400) with a 81– 140 µm wide posterior bulb. Nerve ring and excretory pore lie 340 –398 µm (av.=369) and 510 – 600 µm (av.=555) respectively from anteriorextremity. vulva lies anterior 145 – 80 µm(av.=112.5).
The valval opening is transversely oval shaped and possessesdouble walled anterior and posterior cuticular lips . A narrow cuticulartransverse groove possessing anterior and posterior cuticular folds is presentat a short distance behind the vulva. In live worm the vagina was seen as astraight muscular measuring 141 µm long.
The uterus occupied most of the body .Theovaries are situated at the posterior half of body .The vagina is extendinginwards to one-third of body diameter, with thicker walls at proximal portion .The uterus contains large number of a thick walled, smooth and elongated eggs (Fig.
4,K) , the egg measured 64.6 x28.6 µm. The tail(Fig.4,I) is filiform tail, 480- 420 µm (av.=450) in length. The cuticle surface of the body isregularly transversely striated, each is 0.
025 mm wide .Mouth opening istriangular . The mouth is surroundedwith six lips(Fig.4,G) .
The 6lips possess 3 oral papillae. Oneach side of the body, the lateral alae is represented by two longitudinal andparallel ridges separated by a smooth cuticular band . About 10-12 longitndinalridges start from cervical region and run posteriorly to end slightly anteriorto the bursa in the male or behind the level of the vulva in the female .