Stored Raisin Product Pests

Matthew FidelibusViticulture and Enology, UC Davis

Two Categories of Raisins Pests

• Insects that primarily feed on drying raisins– Includes Driedfruit Beetle and Raisin Moth

• Insects that primarily feed on dried raisins in storage– Includes Indianmeal moth and Sawtoothed Grain

Beetle

Driedfruit Beetle

• Carpophilus hemipterus L. (Coleoptera: Nitidulidae). Cosmopolitan sap beetle.

• Larvae feed on ripe and overripe fruit including grapes, stone fruit, figs, dates, melons and citrus.

• Adult beetles are attracted to volatiles from fermenting fruit, including bunch rot of grapes

• Fruit must have >30% moisture; living yeast

Adults are dark brown, about 3 mm long, and oval shaped.

Short wing covers leave the tip of their abdomen exposed. Light brown or amber colored spots on their wing covers.

Legs and antennae are reddish,and antennae are knobbed at tips.

Dried Fruit Beetle

Driedfruit beetle larvaAdult females scatter eggs over raisins.

Larvae feed on the flesh of the underside of berrieson drying trays.

Fully grown larva enter soil to pupate; adultsemerge 8 days later.

Feeding, excreta, andcast skins reduce raisinquality.

Controlling Driedfruit Beetle

• Well-dried raisins, free of bunch rots, will minimize infestation

• Attract and kill systems with fermenting baits• Stack and seal boxes of raisins with airtight

plastic or reinforced paper laminate• Stacks may be fumigated with phosphine• Controlled atmosphere (low O2 or high CO2),

or controlled temperature (2 weeks at -18 ◦C)

Raisin moth (Cadra figulilella)

• Larvae feed on ripening and drying grapes, and raisins stored on farms.

• Adult females lay eggs on drying grapes. High day-time temperatures may kill exposed eggs.

• Fully grown larva leave the raisins, pupating in dark, dry cracks.

Raisin moth damage

• Larvae on stored raisins feed chiefly on the ridge crests of the raisins, but may also bore into the flesh.

• They do not completely consume raisins but move about, leaving masses of excreta and webbing.

• One larva can damage about 20 Thompson Seedless raisins.

Raisin moth (Cadra figulilella)

Adults are about 10 mm long, with a 16 mm wing span.

Forewings are light pinkishgray with indistinct markings.

Raisin moth eggs

Raisin moth larva

Raisin moth larva detail

Raisin moth in pheromone trap

Raisin moth control

• Clean up and destroy leftover grape bunches and other fruit in and around the vineyard by autumn, before larvae leave the fruit for overwintering sites.

• Well dried raisins are less attractive to moths• Dried raisins in bins should be covered• Cleaning operations at packinghouse can

greatly reduce egg and worm numbers

Indianmeal moth (Plodia interpunctella )

• Indianmeal moth is one of the most destructive stored raisin pests worldwide.

• Moths lay eggs on raisins in the field and in storage

• Young, first-instar larvae can enter crevices as small as 0.13 mm (1/200 inch), thus infesting commodities in containers thought to be insect-proof.

Indianmeal moth and pupa

Indianmeal moth damage

• Infestations contaminate raisins with excrement, cast skins, webbing, cocoons, and living or dead larvae.

Indianmeal moth management

• Sanitation is key.• Infestations are reduced by processing steps,

including stemming, cleaning, etc.• Heavily damaged raisins are lighter in weight

than undamaged raisins and can be blown out during processing.

• Cleaning storage, processing, and shipping facilities helps minimize infestations

Sawtoothed grain beetle(Oryzaephilus surinamensis)

• Cosmopolitan pest that feeds on practically any stored dried food.

• Adults are 3 mm long, narrow and flat. • Crawls rapidly but does not fly.• Adults are long lived—up to 3 years.

Sawtoothed grain beetle

• Eggs are <1 mm; larva are yellowish white.• Newly hatched larva can pass through very

narrow crevices.• Feeds on all parts of a raisin.

Sawtoothed grain beetle

Sawtoothed grain beetles

Sawtoothed grain beetle management

• Sanitation and fumigation.

Conclusions

• Good drying and strict sanitation practices, from the vineyard through the packinghouse, will help minimize infestations.

• Stored raisins may be disinfested by fumigation.• Fumigation may need to be repeated periodically,

when storage exceeds 60 to 90 days, or after the seal has been disrupted.

Reference for further details

• Grape Pest Management, third edition• http://ucanr.edu/GPM