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TICK SEX AND BEHAVIOR

COPULATION in ticks is unique among animals. The male climbs beneath the female, either while she is feeding or before she feeds. He inserts his mouthparts into her GONOPORE - which lies in the area of the third or fourth pair of walking legs. As he withdraws his mouthparts, he releases a SPERMATOPHORE from his gonopore which adheres to the ventral surface of the female. Ticks remain together in coitus for over a week. The male pushes the spermatophore into her gonopore with his hypostome. Once inside the female, spermatozoa are released from the spermatophore.
Spermatophores are formed in the ACCESSORY GLAND in the male. This structure receives spermatozoa from the paired testes and discharges the completed spermatophore along the median EJACULATORY DUCT.
The female receives the spermatophore in a sac-like structure called the SEMINAL RECEPTACLE. The sperm move up the oviduct to a single horseshoe-shaped ovary where fertilization occurs.
Each fertilized egg produced by the female emerges from her gonopore. Gene's organ is everted and extends forward over the capitulum to the gonopore. It grasps each egg and coats it with a starch-like wax.

Larvae emerge from the eggs, seek a host, feed to engorgement, and eventially molt to form the nymphal instar.
Ixodids may use one, two or three hosts (one for each instar). With each stage of the life cycle, the tick generally moves from the host to the ground. It is common for the female to lay her eggs in cracks and crevices in the ground or walls of buildings.
Ticks are transmitters of disease to man and animals. Hence, they affects man's well-being and more research is required to understand the complex life cycles and feeding patterns of the ticks. Hopefully, a better understanding will enable us to reduce the severity of the diseases they carry.

PHEROMONES AND BEHAVIOR

Sonenshine ("Pheromones and other semiochemicals of the Acari". Ann.Rev. Entomology, 30:1-28,l985) has described the courtship process used by Dermacenter variabilis and D. andersoni. Exerpts of this work are presented in this section of the article.
In ixodid ticks, the FOVEAL GLANDS secrete a volatile sex pherolone called 2,6-dichlorophenol. The foveal glands are located in the porose areas on the dorsal surface of female ixodid ticks. The porose areas are absent in adult males.

The foveal glands are fully developed in the adult female - but are not developed in the larval or nymphal stages.

The pheromone, 2,6-dichlorophenol appears during female maturation and may persist in the unfed females for many months. Pheromone synthesis continues during feeding, presumably replenishing the supply of secreted material. In Dermacentor variabilis, following mating, the glands degenerate and the sex pheromone is absent.

In D. variabilis and D. andersoni, courtship consists of distinct stages guided by two separate pheromones.
2,6-dichlorophenol causes the males to:
l)detatch from the host,
2) initiate searching behavior,
3) orient to the sexually ready female,
4) mounting and palpating the porose areas of the female,
and 5) turning and crawling to the undersurface of the female.

Once underneath, the males locate the female gonopore, insert their chelicerae and after ten to twenty minutes, and in response to a specific genital sex pheromone, deposit their spermatophores into the female gonopore. The genital sex phermone chemical is unknown but does appear to be species specific.

In addition to sex pheromones, some ticks (such as AMBLYOMMA) secrete aggregation/attachment pheromones. This pheromone is secreted by feeding males but attracts unfed males, females, and nymphs

Ticks attracted to the emitting males attach nearby and also are usually clasped by the attached males. The effects produced redults in the formation of conspecific feeding tick groups.

The aggregation/attachment pheromone was found to consist of three components: o-nitropyhenol, methyl salicylate, and pelargonic acid.
Dr. Ventura observed the sttracting and clasping behavior of Ixodes dammini males in the late fall of 1988. The behavior was noted on wild mustard plants (Alliaria officinalis).

ACARACIDES - chemicals that kill ticks and mites - click here