Duddingtonia flagranschlamydospores in nutritional pellets: effect of storage time and conditions on the trapping ability againstHaemonchus contortuslarvae

Abstract

AbstractThe study evaluated the effect of storage time and conditions of nutritional pellets (NP) containingDuddingtonia flagranschlamydospores on itsin vitrotrapping ability againstHaemonchus contortusL3 larvae. The treated batch (200 NP) contained 4 ×  106chlamydospores of the FTH0-8 strain, whereas the control batch (200 NP) was produced without spores. Both NP batches were exposed to four experimental storage conditions: (T1) shelves (indoors); (T2) refrigeration (4°C); (T3) outdoors under a roof; and (T4) 100% outdoors. Each group comprised 48 NP with spores and 48 NP without spores (control). The ability ofD. flagransspores to trapH. contortusL3 larvae was evaluated for 8 weeks for each storage condition. For that purpose, six randomly selected NP with spores were compared to their respective control NP. Each NP was individually crushed. The crushed material (1 g) was placed on the surface of a 2% water agar plate with 200H. contortusL3 larvae. Plates were sealed and were incubated at room temperature for 8 days. The whole content of every plate was transferred to a Baermann apparatus to recover the remaining larvae. There was a clear larval reduction in the NP with spores, compared to the respective control NP in the four storage conditions (P< 0.05). The mean reductions ( ± SEM) of the storage conditions were 67 ± 4.9 (T2), 77 ± 6.1 (T1), 81.5 ± 3.8 (T4) and 82.1 ± 2.5 (T3). Larval reductions were similar at all times and were not affected by storage conditions or storage time (R2< 0.2;P>0.05). The long-term shelf-life of the chlamydospores in the NP suggests that this spore dosage technology is a viable option.