Produce Degradation Pathways and Prevention

Role of Pesticides in Produce Production, Preservation, Quality, and Safety 349

Deep inner tunneling from larvae in the fruit is responsible for the proverbial

“wormy fruit,” contamination with larval feces, rapid internal degradation, and

possible abortion of the fruit. Infestation of apples, pears, peaches, or nectarines by

larvae of the codling or oriental fruit moth [30,36] serves as a typical example. In

cherries, larvae of cherry fruit flies may also separate the pit from the pulp, resulting

in shrunken and deformed fruits that ripen earlier than the uninfested cherries [37].

Moreover, brown rot (Monilinia spp.) usually starts in wormy fruits and then spreads

to other cherries. Similarly, wounds caused by the grape berry moth on damaged

grape berries provide entry ports for numerous fungal pathogens, such as powdery

mildew, downy mildew, or grapevine sour rot, which accelerate grape spoilage [38].

Another source of fungal contamination is the honeydew (excess carbohydrates)

excreted by certain insects, which serves as an excellent growth medium for black

sooty mold fungus. Honeydew drips on fruits and foliage, making spots and causing

their discoloration; this is a problem associated mainly with aphid infestation on

both fruits and vegetables [39]. Other important insect pests producing honeydew

include leafhoppers (problematic, for example, on grapes) or pear psylla. Under

bright sunlight and dry conditions, the honeydew produced by pear psylla can kill

the leaf tissue and produce a symptom called “psylla scorch” [40]. A more serious

problem related to pear psylla is its ability to vector a mycoplasma that causes the

disease “pear decline,” which reduces tree vigor and causes poor fruit set and small

fruit size and may lead to the death of the tree (a similar effect called “psylla shock”

may also induce excessive contamination of the tree tissue by pear psylla toxin) [40].

Transmission of plant diseases represents an additional problem associated with

insects and certain other pests that actually may be even worse than the insect-

feeding itself. Among these, aphids are the most important group of viral vectors

[41]. For instance, the banana aphid transmits banana bunchy top virus, resulting in

no fruit production and stunted leaves (“bunchy top”) [42], and numerous other

aphids, such as green peach, pea, or bean aphids, are vectors for other viruses (lettuce

mosaic virus, pea streak virus, etc.) that seriously affect many plants [43]. Important

Strawberries Lygus/tarnished
plant bug
Lygus lineolaris
Lygus hesperus

Feeding on flowers and developing

fruits resulting in fruit deformations

and reduced size

Azinphos-methyl,

bifenthrin,

endosulfan,

fenpropathrin,

malathion, methomyl,

naled

aGrapefruits, lemons, limes, oranges, and tangerines

Source:National Scientific Foundation Center for Integrated Pest Management and USDA Crop Profiles
Web site, available at http://pestdata.ncsu.edu/cropprofiles/.

TABLE 11.3
Examples of Fruit Insect Pests in the U.S., Major Problems They Cause,
and Insecticides Used for Their Control (continued)

Commodity Insects Problems Insecticides