Supplementation of ascorbic acid 2-monophosphate during the early postlarval stages of the shrimp Penaeus vannamei

A culture trial was performed using five levels of ascorbic acid 2-monophosphate (AmP at 0, 10, 100, 1000 and 2000 mg kg⁻¹ diet, expressed as active ascorbic acid, AA) in a semipurified diet for early postlarval Penaeus vannamei. The experiment started 10 days after metamorphosis of the mysid larvae into postlarvae (=PL10). Each treatment was run in four replicates. P. vannamei postlarvae showed significantly better growth according to dietary AA level after 25 days of feeding, i.e. at PL36 stage. Whereas the dry weight of PL36 in the control treatment (0 mg AA kg⁻¹ diet) was only 2 mg, supplementation of 1000 mg AA kg⁻¹ increased the shrimp dry weight up to 18 mg. However, the growth in the other treatments was not significantly different from the control. Fitting a broken-line regression to the biomass yield demonstrated an optimal dietary level of 130 mg AA kg⁻¹ diet. There were no differences observed among the treatments in stress resistance of postlarval P. vannamei to a salinity shock.     

Colletotrichum acutatum associated with Dryocosmus kuriphilus galls on Castanea sativa

The occurrence of Colletotrichum acutatum J. H. Simmonds in necrotized galls of Dryocosmus kuriphilus Yasumatsu in chestnut (Castanea sativa Miller) stands is reported for the first time in Italy. Morphological and biomolecular analyses confirmed the isolation of the fungus. No damage by the fungus has been observed.     

The insect vector Cacopsylla picta vertically transmits the bacterium ‘Candidatus Phytoplasma mali’ to its progeny

The phloem‐sucking psyllid Cacopsylla picta plays an important role in transmitting the bacterium ‘Candidatus Phytoplasma mali’, the agent associated with apple proliferation disease. The psyllid can ingest ‘Ca. Phytoplasma mali’ from infected apple trees and spread the bacterium by subsequently feeding on uninfected trees. Until now, this has been the most important method of ‘Ca. Phytoplasma mali’ transmission. The aim of this study was to investigate whether infected C. picta are able to transmit ‘Ca. Phytoplasma mali’ directly to their progeny. This method of transmission would allow the bacteria to bypass a time‐consuming reproductive cycle in the host plant. Furthermore, this would cause a high number of infected F₁ individuals in the vector population. To address this question, eggs, nymphs and adults derived from infected overwintering adults of C. picta were reared on non‐infected apple saplings and subsequently tested for the presence of ‘Ca. Phytoplasma mali’. In this study it was shown for the first time that infected C. picta individuals transmit ‘Ca. Phytoplasma mali’ to their eggs, nymphs and F₁ adults, thus providing the basis for a more detailed understanding of ‘Ca. Phytoplasma mali’ transmission by C. picta.