North America, praziquantel is currently marketed only in combination with macrocyclic lactones, and the combination formulation is that of the parent compound (ivermectin if paste, moxidectin if a gel).


Appendix C: Effects of Temperature on Infective Strongyle Larvae


Table A1. Effects of temperature on the survival, development, and persistence of free-living stages (eggs, L1, L2, L3) of strongyles (Nielsen et al., 2007). Development


Temperature Range


No development above this level


Optimal temperature range for development of eggs and larvae. Reach infective L3 stage in as little as 4 days.


Eggs develop into L3 within 2-3 weeks.


Lower limit for egg hatching is about 6 oC. At temperatures in this range, development will take several weeks to a few months.


No hatching and no development No development during frost


Alternation between freezing and thawing will usually not lead to development unless temperatures exceed 6 oC


> 40 oC > 104 oF


25–33 oC 77– 91 oF


Survival


Free-living stages die rapidly. Intact fecal balls may retain enough humidity to enable L3 to survive for some weeks.


Larvae survive on the shorter term (i.e., a few weeks), but conditions are too warm for long-term survival


10–25 oC 50–77 oF


6–10 oC 43–50 oF


L3 capable of surviving for several weeks to a few months


L3 survive for many weeks and months under these circumstances


0–6 oC


32–43 oF < 0 oC


< 32 oF


< 0 > oC < 32 > oF


Eggs and L3 can survive for several months at temperatures just above the freezing point


Developing larvae (L1 and L2) are killed, but unembryonated eggs and L3 can survive and persist for long periods (i.e. months)


Repeated freeze-thaw cycles are detrimental to egg and larval survival


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