Timing of Ixodes scapularis (Acari: Ixodidae) Oviposition and arval Activity in Southern New York

Abstract

Timing of oviposition and larval eclosion for fall- and spring-fed female blacklegged tick, Ixodes scapularis Say, and effect of temperature on those events in southern New York state, where Lyme disease is endemic, were determined in the field. We also examined seasonal pattern of larval host-seeking activity, as well as rate of survival for overwintering, unfed larvae. Totals of 9 and 8 replete female I. scapularis were released in fall 1988 and spring 1989, respectively. For the 10 females that oviposited, egg laying began in mid-to-late May, regardless of when ticks had fed. Likewise, larval eclosion was synchronized in July for all egg masses. Microhabitat temperatures experienced by females were not reliable indicators of female reproductive success, in terms of either presence or absence of eggs, or numbers of larvae recovered. However, average body size was significantly greater for females that oviposited successfully than for those that did not. The percentage of unfed larvae surviving the 8-mo overwintering period from late August to early May ranged from 1.9 to 31.4, with a mean survival rate of 10.4%. Concurrent drag sampling through the year indicated a bimodal pattern of larval abundance marked by a relatively small early peak of activity in late May that extended into early July. Because the first peak of larval activity occurred during the period of oviposition, 8 wk before onset of larval eclosion, it appears that bimodality represents activity of 2 consecutive cohorts, with the early peak composed of overwintering survivors. These data imply variation in timing of reproduction and larval activity from 1 geographic area to another. Efforts to devise a comprehensive scheme for the life cycle of I. scapularis must consider that population differences may exist.

Invasion of the Lyme Disease Vector Ixodes scapularis: Implications for Borrelia burgdorferi Endemicity

“…Whereas neither our data nor that of Gatewood et al (2009) show significant larval activity in the late summer, late summer larval activity of greater (Northeast) or equivalent (Midwest) magnitude to early summer activity has been reported (Daniels et al, 1996;Jones and Kitron, 2000;Kitron et al, 1991). In the Northeast, the early peak in May-June represents the remainder of the cohort of larvae that hatched the previous July and successfully overwintered, whereas the second peak of higher magnitude in August represents the subsequent cohort of newly hatched larvae from recently laid eggs by adults that were active in spring as well as the previous fall (after ovipositional diapause; Daniels et al, 1996).…”

“…Whereas neither our data nor that of Gatewood et al (2009) show significant larval activity in the late summer, late summer larval activity of greater (Northeast) or equivalent (Midwest) magnitude to early summer activity has been reported (Daniels et al, 1996;Jones and Kitron, 2000;Kitron et al, 1991). In the Northeast, the early peak in May-June represents the remainder of the cohort of larvae that hatched the previous July and successfully overwintered, whereas the second peak of higher magnitude in August represents the subsequent cohort of newly hatched larvae from recently laid eggs by adults that were active in spring as well as the previous fall (after ovipositional diapause; Daniels et al, 1996). In the Midwest, the separate peaks observed by some researchers at some sites are posited to result from the separate oviposition periods of the spring and fall adults (Jones and Kitron, 2000;Kitron et al, 1991), whereby the early larvae may result from oviposition by fall adults and the late summer larvae result from oviposition by spring adults.…”

Climate and Tick Seasonality Are Predictors of Borrelia burgdorferi Genotype Distribution

“…Because larvae do not hatch from eggs until July, it has been hypothesized that the small, earlier June peak in larval activity comprises larvae that were unsuccessful at finding a host in the preceding autumn and resumed activity in spring after overwintering (14). We observed a similar pattern among sites characterized by asynchronous peaks in immature ticks host seeking in the present study (Fig.…”

Investigation of Relationships Between Temperature and Developmental Rates of TickIxodes scapularis(Acari: Ixodidae) in the Laboratory and Field

“…Larvae were predicted to molt into nymphs in April and May 1991 slightly in advance of the observed period of questing, but temperatures in April and early May of that year (being Ͻ15ЊC) are likely to have delayed host seeking activity of nymphs (Vail and Smith 2002) until the end of May when temperatures increased. A postmolting or hatching delay in questing larvae of up to a month has been observed in I. scapularis in the Þeld (Daniels et al 1996).…”