GUAVA MOTH UP­DATE

Guava moth has been on fei­joa grow­ers’ radar since its ini­tial dis­cov­ery in 1997 in the Far North.

The Orchardist - - Feijoas -

Asha Ch­ha­gan and Natalie Page, en­to­mol­o­gists from Plant & Food Re­search, Auck­land, up­dated grow­ers on what is known about the pest and pri­or­i­ties for up­com­ing re­search.

They said the adult moth is noc­tur­nal so feeds and mates at night. It lays eggs in crevices on a wide host range of fruit, and in the first of sev­eral lar­val stages, the hatch­ing cater­pil­lar burrows into fruit some­times caus­ing pre­ma­ture fruit to drop. The fi­nal lar­val stage pu­pates on the ground cov­ered by soil par­ti­cles af­ter hav­ing spun a loose co­coon.

Un­til 2003, guava moth was largely con­fined to North­land but since 2014 it has spread fur­ther south to Auck­land and in 2017 was found in north Waikato and Coro­man­del. And it isn’t con­fined to fei­joas and guavas hav­ing been found on na­tive karaka, per­sim­mons, macadamias, ap­ples, nashi, peaches, plums, apri­cots grape­fruit, le­mons, man­darins, or­anges, tan­ge­los, lo­quats and ma­genta lilly-pilly.

“There is a two com­po­nent guava moth pheromone lure com­mer­cially avail­able for mon­i­tor­ing, and a lot of anec­do­tal re­ports re­gard­ing control op­tions, but there are cur­rently a lot of gaps in our knowl­edge,” Asha said.

So a Sus­tain­able Farm­ing Fund (SFF) pro­ject was ini­ti­ated to in­ves­ti­gate and pro­vide sus­tain­able man­age­ment op­tions. Plant & Food has been con­tracted to NZ Fei­joa Grow­ers As­so­ci­a­tion for a three-year re­search pro­gramme run­ning to 2020. Con­tri­bu­tions are also com­ing from the NZ Macadamia So­ci­ety, Etec Crop Solutions, Hawke's Bay Re­gional Coun­cil, Gis­borne Dis­trict Coun­cil and North­land Re­gional Coun­cil. The re­search will look at dis­tri­bu­tion, nat­u­ral en­e­mies, lab­o­ra­tory rear­ing meth­ods, semi-chem­i­cal control and in­sec­ti­cide control op­tions.

Dis­tri­bu­tion tri­als have been un­der­way for the last two years in eight re­gions showed none in the Bay of Plenty, Gis­borne, Hawke’s Bay, Taranaki, Manawatu or Nel­son.

So far no par­a­sitoid has emerged from eggs, lar­vae or pu­pae from over 7000 fruit col­lected from more than 200 sites in Auck­land and North­land. Fu­ture re­search will look at semi­chem­i­cal control op­tions, in­clud­ing mass trap­ping, lure and kill, and mat­ing dis­rup­tion. Mass trap­ping will look at var­i­ous den­si­ties of pheromone traps and the re­sult­ing num­ber of male moths caught. Mat­ing dis­rup­tion will re­search the ef­fi­cacy of avail­able twisty ties in­fused with pheromone from a closely re­lated moth.

An­drew Twi­dle from Plant & Food in Lin­coln will be re­search­ing lure and kill pos­si­bil­i­ties. His PhD work will look at what at­tracts fe­male guava moth adults to lay on host fruit and whether this can be used to pro­duce a fe­male at­trac­tant.

And an in­sec­ti­cide trial will look at five dif­fer­ent pos­si­bil­i­ties to re­search their ef­fi­cacy against guava moth with both di­rect and resid­ual treat­ments.

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