Anwar L. Bilgrami

Predatory Abilities of Mononchoides Longicaudatus and M. Fortidens (Nematoda: Diplogasterida) and Factors Influencing Predation

Die rauberischen Fahigkeiten von Mononchoides longicaudatus und Mononchoides fortidens (Nematoda : Diplogasterida) und Faktoren, die das Beutemachen beeinflussen In in vitro Studien wurden die rauberischen Fahigkeiten aller Entwicklungsstadien von Mononchoides longicaudatus und M. fortidens untersucht, einschlieslich Beutefang, Mechanismus der Nahrungsaufnahme, Umfang des Beutemachens bei Adulten und Juvenilen, Beutebevorzugung sowie der Einflus der Anzahl Beutetiere, des Hungers der Rauber und der Temperatur auf das Beutemachen. Die Mechanismen des Beutefangs und der Nahrungsaufnahme werden in funf Phasen eingeteilt: Begegnung mit der Beute, Angriffsreaktion, Angriff, Speichelabgabe/extrakorporale Verdauung und Nahrungsaufnahme. Die meisten Phasen waren bei beiden Raubern vergleichbar. M. fortidens fing haufiger und brauchte weniger Zeit zum Verzehr der Beute als M. longicaudatus. Letzterer prufte seine Beute sanfter und fur langere Zeit, wahrend die Prufung von M. fortidens heftiger und kurzer war. Die Rate des Beutemachens blieb bei mannlichen und weiblichen Raubern uber zwolf Tage hinweg gleich. Sie wurde durch die Anzahl der vorhandenen Beutetiere, den Hungerzustand der Rauber und die Temperatur gesteuert. Der hochste Beutefang fand in einer Population von 200 Beutetieren bei 25-30°C mit Raubern statt, die 12 Tage gehungert hatten. Acrobeloides sp., Cephalobus sp., Panagrellus redivivus und die J2-Stadien von Meloidogyne incognita und Anguina tritici wurden von den beiden Raubern am starksten bevorzugt. Hoplolaimus indicus und Hemicriconemoides mangiferae wurden nicht gefressen.

Analysis of the Predation By Aporcelaimellus Nivalis On Prey Nematodes From Different Prey Trophic Categories

Numerical analysis of the predatory behaviour of Aporcelaimellus nivalis, including strike rate encounters resulting in attack, attacks resulting in wounding, feeding after wounding, prey left unconsumed and duration of feeding upon an individual, was made in relation to five different prey trophic categories: 1) Bacterial feeders (Saprophagous nematodes), 2) Migratory juveniles (Sedentory endoparasitic nematodes), 3) Epidermal feeders (Ectoparasitic nematodes), 4) Cortical feeders (Ectoparasitic nematodes) and 5) Predatory nematodes. The degree of susceptibility on individual prey and prey trophic categories as a whole was found to vary. The endoparasitic nematodes were highly susceptible (prey susceptibility = 77%) but predators resisted predation well (prey resistance (PR) = 78%). Characteristics such as thick body cuticle, body annulations and thick longitudinal cuticular folds provided physical resistance to Hoplolaimus indicus, Scutellonema sp., Hemicriconemoides mangiferae, Hemicycliophora dhirendri and Mononchoides fortidens (PF= 100%). Mononchus aquaticus and Rhabditis sp. exhibited behavioural resistance in the form of rapid undula. tory movements and took evasive action when attacked. No individuals of Helicotylenchus indicu. were consumed by the predators. This was attributed to unfavourable/toxic prey contents (chemical resistance). Duration of feeding on an individual prey depended on the size of the prey and other physical and chemical factors.

Predatory Behaviour of Aqua Tides Thornei (Nygolaimina: Nematoda)

Studies on its predatory behaviour revealed that Aquatides thornei was not attracted towards live nor bisected prey nematodes, but made contact with the prey by chance: labial contact was necessary to initiate an attack. Several predators aggregated and fed on prey injured by another predator. No preference was shown for any part of the body for attack; Rhabditis sp. was selected in preference to Chiloplacus symmetricus. A. thornei seemed to paralyse the prey after its mural tooth was inserted deep into the body. Ingestion was intermittent with short periods of sucking activity, the duration of feeding on a single prey varied from 3-5 min to 4-6 h. Little variation was found in the daily rate of predation during 12 days. The rate of predation increased as the number of prey increased. Maximum predation occurred with 150 prey and least with 25 prey nematodes.

A scanning electron microscope study on mononchoides fortidens (Schuurmans-Stekhoven, 1951) Taylor & Hechler, 1966

Detailed SEM observations were made on Mononchoides fortidens (Schuurmans Stekhoven, 1951) Taylor & Hechler, 1966. The cuticle is marked with fine transverse striations and prominent longitudinal ridges or folds. The lip region is continuous and the lips are not prominent. Each lip bears a single papilla but in males four additional setose cephalic papillae are present. The stomal opening is slit-like, bordered by 13-15 bifid cheilorhabdial filaments. Amphids are small and elliptical and situated post-labially. The stoma has a prominent dorsal tooth with an opening of the oesophageal gland. Other structures in the stoma include a subventral pyramidal tooth, ventro-lateral toothlets or denticles, a dorsal plate and paired dorso-lateral plates. The cheilorhabdions are apparently not fused but rib-like, appearing as bifid structures in face view. The vulva is circular, situated between two longitudinal ridges. The male posterior region has nine pairs of papillae of which three are pre-cloacal and six post-cloacal. Phasmids are large pore-like.

Observations On the Predation Ability of Aporcelaimell Us Nivalis (Altherr, 1952) Heyns, 1966 (Nematoda: Dorylaimida)

Predation by Aporcelaimellus nivalis depended largely on chance encounters with the prey but the pre-feeding attraction and aggregation of up to 7 predators around an already injured prey at a feeding site is an indication of positive perception of prey body fluids. Prey catching and feeding mechanisms comprised five distinct phases viz., encounter with prey, attack response, attack, salivation/extra-corporeal digestion and ingestion/feeding. Rate of predation remained unchanged over a period of eight days but prey number, temperature, agar concentrations, starvation of the predators, type of the prey etc., determined predation. A. nivalis preferred second stage juveniles of Meloidogyne incognita (Kofoid & White, 1919) Chitwood, 1949 and Heterodera mothi Khan & Husain, 1965 to other species of prey nematodes. No predation took place when Hoplolaimus indicus Sher, 1963, Helicotylenchus indicus Siddiqi, 1963 and Hemicycliophora sp. were used as prey; thick cuticle, body annulations and toxic or unfavourable prey secretions were considered the likely cause. Adult (male and female) A. nivalis killing maximum number of prey nematodes was the most active predator stage.