Occurrence and impact of pasture mealybug (Balanococcus poae) and root aphid (Aploneura lentisci) on ryegrass (Loliumspp.) with and without infection byNeotyphodiumfungal endophytes

Abstract

Pasture mealybug (Balanococcuspoae) was found infesting two field trials evaluating the performance of selected strains of the endophyte Neotyphodium lolii in ryegrass (Lolium spp.) in Canterbury, New Zealand. Deterioration of endophyte-free plots relative to endophyte-infected plots had been observed. In Trial A, pasture mealybug were sampled in plots of the perennial ryegrass cultivar 'Grasslands Nui', without endophyte (nil), or infected with the wild-type endophyte, or the selected strains, AR1 and AR37. In Trial B, mealybug numbers on six ryegrass cultivars infected with AR1 or wild-type were compared with those on the same cultivars without endophyte. In sampling these trials, the presence of a root aphid, Aploneura lentisci, was also noted. Populations of mealybug in both trials were similar on all endophyte-infected treatments and significantly lower than populations on nil treatments. Neither AR1 nor wild-type appeared to reduce root aphid numbers, while AR37 may have had some effect. The amount of dead grass was significantly greater in nil than in endophyteinfected plots in Trial A, and yield of ryegrass was correlated with numbers of mealybug and root aphid present. Pasture productivity in nil treatments had recovered by spring, in the year of the outbreak. The presence of endophyte, strain of endophyte and cultivar were all significant factors affecting both total dry matter and green yield in Trial B. Pasture mealybug accounted for 55% of the variation in a decline in growth rate that occurred in this trial over the summer-autumn periods between 2000 and 2001, particularly in the nil treatments. Two years after the outbreak there was 25% less ryegrass and persistently lower pasture yields in nil plots. We conclude that pasture mealybug are capable of inflicting severe damage to endophyte-free ryegrass in Canterbury, particularly during dry summer-autumn periods.

Endophyte Isolate and Host Grass Effects on Chaetocnema pulicaria (Coleoptera: Chrysomelidae) Feeding

“…The insect resistance of novel associations must be based on experimental studies such as this and not on assumptions from known chemistry. Furthermore, this study, together with others (Ball et al 1994(Ball et al , 2006Popay and Wyatt 1995;Pennell et al 2005), establishes that there are unknown insect resistance factors in some grassÐ endophyte associations requiring further elucidation.…”

“…Two associations (AR17, AR37) strongly reduced feeding but lacked the common alkaloids. AR37 produces epoxy-janthitrems (Tapper and Lane 2004) and has been shown to be active in grasses against a range of insect species, including H. arator (Ball et al 1994), L. bonariensis (Popay and Wyatt 1995), S. frugiperda (Ball et al 2006), mealybug Balanococcus poae (Maskell) (Pennell et al 2005), and aphid Aploneura lentisci (Passerini) (Popay and Gerard 2007). The direct effect of epoxy-janthitrems on insects has yet to be determined.…”

Currencies of Mutualisms: Sources of Alkaloid Genes in Vertically Transmitted Epichloae

“…Such a situation is expected to select for mutualism because the fitness of a vertically transmitted symbiont links positively to host fitness [41,42]. A common benefit conferred by epichloae to their hosts is the production of protective alkaloids that can deter, impair or even kill invertebrate and vertebrate herbivores [1,3,4,22,43,44,45,46,47,48,49,50,51,52,53]. Whenever a hybrid forms, its fitness may depend on the alkaloid biosynthesis capabilities that it has obtained from its ancestors.…”

A Review of Perennial Ryegrass Endophytes and Their Potential Use in the Management of African Black Beetle in Perennial Grazing Systems in Australia

“…Endophytes have been reported to offer protection against a number of insect pests, including black cutworm ( Agrotis ipsilon ) (Baldauf et al, 2011), pasture mealybug ( Balanococcus poae ) (Pennell et al, 2005), Argentine stem weevil (Prestidge and Gallagher, 1988b), root aphids (Popay and Thom, 2009), and Japanese beetle and other white grubs (Scarabaeidae spp.) (Potter et al, 1992) including African black beetle (Bell et al, 2011).…”