Relative efficacy of organophosphorus insecticides against susceptible and resistant strains of the strike blowfly Lucilia cuprina (Calliphoridae) in New Zealand sheep

Four groups of five Romney lambs were treated by plunge dipping with one of four registered organophosphorus flystrike preventatives. Untreated lambs acted as controls. The sheep were challenged at weekly intervals with larval implants of organophosphate-susceptible and -resistant strains of Lucilia cuprina. All four treatments provided 19-21 weeks protection against susceptible larvae but chlorfenvinphos provided the longest protection (16-17 weeks), followed by propetamphos (15-16 weeks), dichlofenthion (10-13 weeks) and diazinon (9-13 weeks), against the resistant strain.     

Combined effect of generally regarded as safe (GRAS) compounds andTrichoderma harzianum on the control of postharvest diseases of rambutan

Botryodiplodia theobromae, Colletotrichum gloeosporioides andGliocephalotrichum microchlamydosporum are the causal fungi of the rambutan postharvest diseases stem-end rot, anthracnose and brown spot, respectively. Two different treatments of rambutan fruits(Nephelium lappaceum) against the three pathogens were compared: potassium metabisulphite (250 ppm) or cinnamaldehyde (30 ppm), each combined withTrichoderma harzianum (TrH 40). The application of TrH 40 and potassium metabisulphite effectively controlled the incidence and severity of the three postharvest diseases and maintained the overall quality and color of the fruit under low temperature storage at 13.5°C and 95% r.h. for 18 days. The greatest effect of this treatment was shown onG. microchlamydosporum. Cinnamaldehyde affected the growth and germination of TrH 40, whereas potassium metabisulphite did not. http://www.phytoparasitica.org posting Nov. 4, 2001.     

Diversity of the coat protein-coding region among Ilarvirus isolates infecting hop in Australia

Coat protein (CP) sequences of 17 Ilarvirus isolates were obtained from hops at three farms in Tasmania, Australia. Phylogenetic analysis of these sequences and additional database sequences indicated several Apple mosaic virus (ApMV) isolate clusters distinct from Prunus necrotic ringspot virus (PNRSV): one containing isolates from apple; one containing a single isolate from almond; a third containing Australian hop isolates of the 'apple' serotype and a German isolate of unknown origin; and a fourth containing Australian hop isolates of the 'intermediate' serotype. Isolates from hop, pear and prune from the Czech Republic either formed a fifth grouping, or were divergent members of the 'intermediate' serotype group. Deduced amino acid (aa) residue differences between the coat proteins of the two hop isolate serotype groups were highlighted as possible regions of serological differentiation. No evidence for coinfection of plants with both serotypes was found. Tests of ApMV-infected hop buds using the Shirofugen flowering cherry assay revealed a possible differentiation of the two strains based on hypersensitivity. Because of serological similarities to PNRSV, these viruses have commonly been reported as strains of PNRSV. However, this study shows ilarviruses from Australian hops are strains of ApMV, but distinct from those infecting Malus spp.     

Comparative ecologies of domestic and naturalised rainbow trout in northern Lake Huron

Northern Lake Huron (Ontario, Canada) supports the largest concentration of freshwater salmonid cage culture farms in Canada and receives inputs of domestic‐strain rainbow trout (Oncorhynchus mykiss) through escapement. We assessed the potential effects of these domestic fish on the naturalised rainbow trout of this ecosystem by comparing their respective ecologies. Mature adults were sampled from spawning tributaries, primarily in spring, and to a lesser extent in fall. Fish of domestic origin comprised ~80% of rainbow trout sampled from sites near cage culture facilities but <20% of rainbow trout sampled from more distant sites. Domestic adults in spawning condition (gametes free‐flowing) were present in the spawning tributaries in both spring and fall sampling seasons, whereas naturalised fish in spawning condition were only observed in the spring. Domestic adults were younger and smaller (in length), appeared to have shorter lifespan and had a higher male to female ratio compared with their naturalised counterparts. Growth rates (change in length with age) of naturalised and domestic females in the wild were similar, but domestic males grew more slowly than naturalised males. Domestic females also produced smaller eggs than naturalised females. Food web positions (inferred from δ¹³C and δ¹⁵N) of domestic and naturalised fish were very similar but varied more strongly with body size in the former. Domestic‐strain rainbow trout of cage culture origin can survive, grow and attempt to spawn in northern Lake Huron and have the potential to compete for food, mates and spawning habitat with naturalised rainbow trout.