VPA 221: Veterinary Entomology and Acarology (1+1)

Difference between soft and hard ticks

DIFFERNCE BETWEEN SOFT AND HARD TICKS

Characteristics	Argasidae		Ixodidae
MORPHOLOGY
I.  Capitulum
Location	Subterminal and so not visible on the dorsal aspect of adults Terminal and visible from dorsal aspect in larval stages	Terminal, visible from the dorsal aspect in all stages
Basis capitulum	Porose areas are absent	In female ticks the porose areas are seen on the dorsal aspect of basis capitulum
Pedipalps	Leg like, all 4 articles sub equal and flexible	Article IV recessed in a cavily in article III and the 1st article of the pedipalp is rigid
Chelicerae	Cheliceral sheath is smooth and distended	Cheliceral sheath is covered with teeth/ spines
II. Body
Appearance of the surface	Leathery, mammillated or wrinkled	Smooth or superficially striated
Scutum	Absent	Present, entire dorsal surface covered in male ticks, half the surface covered in nymphs and larvae while in females only 1/3 rd of the dorsal surface is covered by scutum
Festoons	Absent	Present
Eyes ( when present )	Ventro-lateral on the supra coxal fold, 2 pairs, between 1st and 2nd and 2nd and 3rd pair of legs	Dorso-lateral in position, one pair is seen between the 1st and 2nd pair of legs
Spiracles	Small, seen between the 3rd and 4th coxae on ventral aspect	Seen on large spiracular plates posterior to the 4th coxae
Plates/grooves	Absent	Present
III. Legs
Coxae	Unarmed	Armed, with internal and external spurs
Pulvilli	Rudimentary or absent	Present
IV. Sexual dimorphism
	Not marked	Marked
BIOLOGICAL CHARACTERS
Feeding habits	Intermittent feeders, rapid feeding in case of nymphs and adults, could also be slow in larval stages, cuticle expands to accommodate the blood meal but does not grow. They feed for few hours on the host and hence there is no formation of attachment cement	Takes a single blood meal over a period of days. Slow feeder and hence attachment to the host becomes essential, they secrete attachment cement Cuticle grows to accommodate the large blood meal
Nymphal instars	Many	Only one
Mating	Off the host Single sex pheromone	On the host with the exception of Ixodes spp Multiple pheromone
Reproduction	200-300 eggs deposited by the female after each feeding Several batches of eggs are laid, so females feed and oviposit repeatedly Eggs emerge from opening on ventral side Eggs are waxed by the Gene's organ	Following engorgement the mated female deposits around 10,000-20,000 eggs per tick Only one batch of eggs and following oviposition the female tick shrivels and dies Eggs emerge from the dorsal aspect through a slit in between the scutum and basis capitulum Initially covered by the secretion of the accessory glands of the vagina followed by the Gene's organ
Host seeking behavior	Nidiculous, seen in protected areas such as the nest, cave, burrow etc of the host	Non nidiculous, seen in pastures and other areas where the host frequents, it ambushes the host
Seasonal activity	Active throughout the year	Active during the warmer months of the year
Habitats	Sheltered environments	Open environments
Life span	Long lived, infrequent blood meals, numerous nymphal stages and high resistance to starvation are the causes for the increase in life span	Not so long lived. Less resistant to starvation, only one nymphal stage and single blood meal