Role of Pesticides in Produce Production, Preservation, Quality, and Safety 351
examples of bacterial vectors include striped and spotted cucumber beetles that
transmit Erwinia tracheiphila to cucumbers and other cucurbits causing bacterial
wilt disease leading to plant death [44]. Basically, it is very difficult and mostly
impossible to cure plant diseases and save the affected plants. Thus, insecticides
play an important role in plant disease management by killing the disease vectors
[41]. Moreover, the use of insecticides is still the most effective tool in combating
insects transmitting grave diseases to humans, such as mosquitoes Anopheles spp.,
which serve as the vectors of malaria.
11.2.2 ACARICIDES
Acaricides (also called miticides) are designed to kill acari, which include ticks,
and, more important for our discussion, mites. The differences in the biochemistry
of acari and insects enable application of compounds highly toxic to mites and
relatively innocuous to insects, although some insecticides (e.g., most organophos-
phates) also possess acaricidal properties [1]. In addition to interference with nervous
system functions, the modes of action of acaricides involve, for instance, inhibition of
oxidative phosphorylation (disruption of adenosine triphosphate, ATP, formation) or
electron transport in mitochondria. Some acaricides are actually ovicides or mite growth
regulators and, in several cases, the mode of action is not known [1,5]. Important
acaricides include clofentezine, fenbutatin oxide, hexythiazox, propargite, and the
bridged diphenyl derivates (closely related to DDT) dicofol and bromopropylate [4].
Mites are very unpleasant pests on many crops and usually become a serious
problem if their natural predators are destroyed from insecticide applications, allow-
ing mite populations to flare. Mites can pierce individual leaf cells with their
mouthparts and ingest the cell contents, including the chlorophyll [45]. This results
in mottled, off-color foliage, which may later appear gray or bronzed and often drop
prematurely. The loss of chlorophyll means reduced photosynthetic capacity of the
Green peach and potato
aphids
Myzus persicae,
Macrosiphum
euphoribaeSucking the plant sap causing
the leaves to curl; vectors of
virus plant diseases (mosaic
virus)Cyfluthrin,
cyhalothrin-lambda,
diazinon, dimethoate,
esfenvalerate,
imidacloprid, phorateaBrassicaceae including, e.g., broccoli, brussels sprouts, cabbage, Chinese cabbage, cauliflower, kale,
kohlrabi.
bCucumbers, zucchini, squash, gourds, pumpkins, watermelons, etc.
Source:National Scientific Foundation Center for Integrated Pest Management and USDA Crop Profiles
Web site, available at http://pestdata.ncsu.edu/cropprofiles/.
TABLE 11.4
Examples of Vegetable Insect Pests in the U.S., Major Problems They Cause,
and Insecticides Used for Their Control (continued)
Commodity Insects Problems Insecticides