Biological control with
beneficial insects makes dollars and sense, even in chemically sprayed cotton
fields. Beneficial insects growing wildly in fields are one of nature's great
free sources of pest control, a resource to augment and nurture, not squander
or slug into oblivion under a pesticidal rain. When properly managed,
biological control organisms can be a valuable part of your cotton profit team.
Costs of sprays, scheduling
sprays when workers are not present, public and worker liability risks, even
insurance costs, may be reduced when biological control organisms assume more
pest management chores in your cotton fields. Residue and resistance problems,
particularly whiteflies and leafminers, are avoidable when pest-fighting
biological control armies are integrated into your cotton pest defense system.
Fifty to 75 percent pest
control cost savings have been reported within the first two years by cotton
growers transitioning from chemical farming to a more sustainable ecological
approach utilizing beneficial organisms. Even gaining a mere few weeks delay in
the onset of spraying by making early releases of beneficials can yield
dramatic monetary gains, with natural biological control substituting for weeks
of pesticide inputs. As if this were not enough, there are also public
relations benefits from using this "green", environmentally-friendly
alternative to conventional chemical control.
COTTON BIOLOGICAL CONTROL
Unsprayed cotton fields host
an army of several million beneficial arthropods per acre, a valuable free
source of natural pest control best nurtured, but all too easily and often
destroyed by harsh pesticide regimens. Bollworms, loopers, aphids, whiteflies,
leafminers, spider mites and other potential pests seldom pose major problems in
cotton fields where the indigenous pest-fighting natural enemies are preserved.
Among the hundreds of
beneficial species commonly devouring cotton pests are green and brown
lacewings, pirate bugs, big-eyed bugs, assassin bugs, damsel bugs, spined
soldier beetles, Staphylinid rove beetles, Carabid ground beetles, Collops
beetles, lady beetles, six-spotted thrips, Tachinid flies, Phytoseiid mites,
spiders and several dozen parasitic wasp species, including Trichogramma.
Two of the 50 potential
cotton pests, the pink bollworm and boll weevil, most consistently elude these
hungry cotton field predators and parasites. Both pinkie and the boll weevil
feed internally on squares and bolls, thereby escaping enough of the common
cotton field beneficials to pose chronic problems.
NEW PINK BOLLWORM EGG
PARASITE
Rincon-Vitova is addressing
the pink bollworm problem by introducing a new natural enemy, Trichogrammatoidea bactrae, an
Australian import that destroys moth eggs before pinkie caterpillars hatch out
and burrow into the hidden safety of their cotton boll feeding niche. Rincon's
entomologists are excited about this new natural enemy, which turns pinkie's
white eggs black, because mated females produce mostly new pest-egg-destroying
females. Field studies in Brazil [Entomophaga 1987. 32(3):241-248] show
that a related Trichogrammatoidea species teams up with other parasitoids to
provide more than 50% caterpillar egg parasitism; with pirate bugs, big-eyed
bugs, spiders and other predators in the natural enemy complex adding another
45% moth egg destruction, total egg destruction is 95.5%.
Few pesticides can match the
95+ percent pest egg destruction potential of the natural enemy complex --
indeed, pests like pinkie lay many eggs so to insure that a few individuals
survive to perpetuate the species in this tough bug-eats-bug natural
environment. The objective of adding new beneficials like Trichogrammatoidea bactrae to the cotton agroecosystem is
strengthening the natural enemy complex, and creating an ecosystem where
predator and prey (pest) are in better balance.
Neither Trichogrammatoidea bactrae nor any other beneficial species sold by
Rincon-Vitova Insectaries is intended to be used as a pesticide for quick
insect kill. Trichogrammatoidea bactrae,
Trichogramma pretiosum, green
lacewings, predatory mites and other Rincon-Vitova beneficials need to be
integrated into agroecosystems, and nurtured into reproducing in the field.
Releases of Rincon-Vitova's biological control organisms are intended to
augment existing natural enemies, thereby tipping the balance of nature towards
more biological pest control.
Harnessing and working in
harmony with ecological processes to grow biological control organisms in
cotton fields is a totally different process from chemical pesticide use.
Creating sustainable biological control in cotton requires a change in
thinking, as the rules are very different from chemical pest control. Even
economic thresholds for pesticide treatments change when cotton fields are
teeming with biological control organisms. When beneficials are on patrol in
cotton fields, higher pest levels can be tolerated for longer periods of time
without pesticide use, which translates into immediate bottom line pest control
cost savings.
Rincon-Vitova's beneficial
insects (all natural, none genetically engineered) are small pest-fighting farm
animals, not pesticides. The state of Texas agrees that beneficial insects are
farm animals, and, like cattle and pigs, exempts beneficial insects (as farm
animals) from state sales tax. We oppose government regulatory agency
expenditures of taxpayer monies (e.g. Cal-EPA) to regulate these tiny
pest-eating farm animals as toxic chemical pesticides subject to the same
costly regulatory policing policies as the toxic chemicals that brought on the
current environmental crisis and consumer distrust of agriculture -- beneficial
insects are part of the solution, not the problem.
When combined with
sustainable cotton growing practices to encourage predators and parasites,
periodic early season releases to establish Trichogrammatoidea
bactrae, and inoculative releases of other Rincon-Vitova beneficials, can
be cost effective, at least delaying the onset of costly chemical spray
programs. Trichogrammatoidea bactrae
and other beneficials are compatible with "soft pesticides" like BTs
(e.g. Dipel, Javelin), sterile male releases and pheromone mating disruption
(e.g. Attract 'n Kill and NoMate), making them good additions to integrated
pest management (IPM) programs.
Rincon-Vitova Insectaries
invites interested cotton growers and their PCAs to participate with us in
evaluating the addition of Trichogrammatoidea
bactrae to the cotton field natural enemy team against pinkie. This
generalist beneficial insect is available to any cotton farmer. However,
advance orders are required, as we are limiting production of this perishable
living product (T. bactrae), and will
not have the capacity to accept most last minute orders.
TRANSITIONS TO BIOCONTROL
MADE EASIER
Rincon-Vitova tries to make
the transition from heavy reliance upon pesticides to sustainable biological
control as smooth as possible by continually collecting new strains of
beneficials from heavily sprayed agroecosystems. Though we do not specifically
test natural enemies for ability to withstand chemical sprays, we believe that
some of our insects, particularly our green lacewings, great all-around
predators, have been successful in transition situations due in part to this
hardiness and ability to withstand some chemical residues.
Ideally, releases of
beneficials are started as early in the season as possible, when the first
pests enter cotton fields or neighboring crops (e.g. alfalfa, grains,
vegetables) preceding cotton. One of our most popular strategies is initially
releasing small numbers of beneficials to colonize young cotton, and following
up with a series of weekly releases to insure long-term establishment of
pest-destroying natural enemies. Farming ecologically with biological control
inputs gets easier each year, as a reservoir of natural enemies becomes
established.
Where pesticides have not
killed off the natural enemies, most potential pests go unnoticed, as they are
so effectively squelched by resident beneficials. When predators and parasites
are destroyed by spray programs or starved away by lack of prey, releasing
Rincon-Vitova's green lacewings, Trichogramma and other beneficials helps
restore the natural balances found in unsprayed agro-ecosystems. Early season
releases of insectary-grown beneficials are the backbone of reestablishing
biological control. It is like restocking the fish pond when one starts
releasing beneficials to rescue natural-enemy-depleted farms from the pesticide
treadmill.
Rincon-Vitova Insectaries
started out rearing Trichogramma egg parasites for cotton growers in 1960, and
currently rears several different Trichogramma species adapted to a variety of
crops and caterpillar (worm) pests. Rincon's Trichogramma pretiosum attacks eggs of numerous cotton moths,
including bollworms and leaf worms.
Limited quantities of the
tiny lady beetle Delphastus pusillus,
a voracious predator of sweetpotato and poinsettia whiteflies, can also be
inoculated into cotton fields. We advise placing orders well in advance, and
setting aside unsprayed crop refuges to allow the small available inoculative
quantities of Delphastus to reproduce and become a significant whitefly
fighting force.
General predators such as
lady beetles and green lacewings are available to help in early season aphid
control -- these same insects help defeat spider mites after aphids come under
biological control. Late-season biological control of worms (caterpillars) is
an added benefit of holding off on early-season pesticides and allowing small
early-season populations of beneficials to multiply into large mid- to
late-season pest-fighting armies.
FREE SOURCES OF BENEFICIALS
Slight modifications in
farming practices and ecological planting schemes can create cotton
agro-ecosystems more closely emulating natural ecosystems, and promote the
in-field production of millions (per acre) of voracious pest-eating beneficials
at no additional cost to cotton growers. This free source of indigenous natural
enemies, which would be prohibitively expensive to purchase, consistently
controls sweetpotato whitefly and cotton aphids in unsprayed cotton
agroecosystems.
Understanding the movement
of natural enemies between crops is the key to unleashing this vast free source
of biological pest control. Though there are differences among cotton growing
areas, some general principles apply. Cotton field populations of dominant
natural enemies are markedly increased when cotton agro-ecosystem diversity is
increased, as compared with large cotton monocultures (one crop).
Biological control is also maximized
when alternate crops act as field insectaries, growing large populations of
pest-fighting predators and parasites that can migrate into cotton. Cotton
interplanted with or growing adjacent to unsprayed alfalfa hay, sorghum,
sunflower borders, vegetables, small grains, oil seed Brassicas, etc. attracts
a wide variety of natural enemies, including lady beetles, green lacewings,
Tachinid flies, big-eyed bugs, spiders, pirate bugs, predacious beetles and
several genera of parasites that effectively control sweetpotato whitefly,
bollworm, cotton aphids and other potential pests.
In integrated planting
systems it is not unusual for minimally sprayed vegetable crops to produce more
than four million parasites per acre, many of which migrate freely into adjacent
crops, including cotton, and provide cheap (free) biological control. For
example, a recent study of inoculative of Trichogramma on 667 acres of
vegetables resulted in biological control on 3500 acres of adjacent cotton,
with 60 to more than 90 percent parasitism of cotton caterpillars [Chinese
Journal of Biological Control 1985. 1(4):2-7]. Experiences are similar in
California and elsewhere when beneficials are allowed to grow (i.e. not killed
off with broad-spectrum pesticides) in cropping systems overlapping cotton.
From Texas to Africa to China and the former Soviet republics, Trichogramma
releases directly into cotton produce similar dramatic results, provided
growers switch from broad-spectrum pesticides that kill beneficials to IPM
systems emphasizing softer materials like insect growth regulators, microbials,
pheromone mating disruption etc.
Rincon-Vitova advises cotton
growers to work closely with PCAs skilled in IPM methods such as beneficial
insect releases, mating disruption, selective pesticides easy on beneficials,
and spot spraying. If it is necessary to knock runaway pest populations down to
levels that small populations of newly-introduced beneficials can easily mop
up, use least-toxic, low-residual spray materials. The goal of spraying
(selective use of pesticides least toxic to beneficials) is lowering pest
populations to tolerable levels, not pest eradication. Low pest populations and
innocuous alternate prey are necessary to feed biological control organisms.
Without prey, predators and parasites are scarce. Hence, a few minor cotton
pest situations must develop and be tolerated, in order to obtain and maintain
a buffering natural enemy complex that subsequently controls major pest
problems.
Planting legume, green
manure, cover crop or alfalfa refugia (safe havens that are never sprayed)
mimics the natural movement of beneficials from crop to crop. For example,
alfalfa hay attracts aphids, mites and worms (few of which attack cotton) that
nourish large pest-fighting populations of predators and parasites, a no-cost
biological control army available to control pests in nearby cotton fields.
ALFALFA, KING OF THE
INSECTARY CROPS
There are over 1,000 insect
species in an average alfalfa field, the majority of which are beneficial, making
alfalfa, along with sorghum, the main "insectary" crop in many
agroecosystems. Agrichemical West magazine (July 1960) noted, "In
Imperial Valley, alfalfa is the only large acreage crop grown throughout the
year. Hence it is the principal reservoir of beneficial insects in that area.
Conserving the beneficial insects therefore benefits growers of many other
agricultural crops in the same region." A neglected lesson, unfortunately
being relearned the hard way by Imperial Valley growers combating leafminers,
whiteflies and other pests artificially created by pesticide destruction of
biological control organisms in insectary crops like alfalfa.
In 1956, at the height of
the University of California's statewide `war' against spotted alfalfa aphid,
researchers discovered that strip farming alfalfa, instead of harvesting entire
alfalfa acreages simultaneously, dramatically increased the number of
biological control organisms, and reduced pest populations. Strip cutting
(harvesting alternate strips or fields) stabilizes the alfalfa agro-ecosystem,
with different-aged hay growths occurring simulatenously in the same or nearby
fields.
When one strip is cut,
alternate strips or fields are half grown, and fields and farms are never
completely bare or without an alfalfa breeding refuge for beneficials. In the
pioneering University of California studies, strip cut alfalfa had more than
one million insect-eating spiders per acre, versus only 105,000 for regularly
harvested alfalfa; 287,000 pest-destroying parasitic wasps, versus 70,000;
401,000 predatory big-eyed bugs, versus 199,000; 205,000 lady beetle adults,
versus 46,000; 232,000 lady beetle larvae, versus 11,000. "By exact count
the strip-farmed field contained four times as many natural enemies, with only
one-fourth the number of alfalfa pests," along with a ton more hay per
acre and no need for insecticides, reported Agrichemical West (July
1960).
As the season advances,
begin mowing alternate strips or fields when cover crops or alfalfa begin to
bloom; cut half and let this start to grow back before mowing the alternates.
Avoid broad-spectrum pesticides at all costs in early season for maximum
production of predators and parasites. Harvesting alternate strips keeps plants
producing predators and parasites throughout the season, forcing a steady
migration of beneficials into nearby cotton. This "battle of the
bugs" takes place without damage to cotton.
Alfalfa is also an excellent
Lygus trap crop. Cutting an entire alfalfa field at one time forces Lygus bugs to
fly into neighboring crops. Nearby uncut alfalfa as a trap crop eliminates the
need to spray cotton for Lygus.
STRIP CROPS STOP BOLLWORM
& BOLL WEEVIL
Strip cropping is better
known as a soil and water conservation technique than as an integrated pest
management (IPM) tool. Strip intercropping, as the practice might be more
accurately termed, is "growing two or more crops simultaneously in
different strips wide enough to permit independent cultivation but narrow
enough for the crops to interact agronomically" (Francis, 1986).
"To be quite
accurate," wrote Harold E. Tower and Harry H. Gardner (1946) in a USDA
Farmers' Bulletin titled Strip Cropping for Conservation and Production,
"strip cropping is not a single practice; it is a combination of good farming
practices. Strip cropping employs crop rotations, contour cultivation, proper
tillage, stubble mulching, cover cropping, and other practices. The
strip-cropping system maintains soil fertility and often increases it,
maintains the maximum amount of ground cover for the greatest possible portion
of the year, provides for the growing of field crops in a systematic
arrangement of strips or bands which serve as vegetative barriers to erosion
and waste of soil, water, and fertilizer. These are the principal and clearest
advantages of the practice -- or system. The principal disadvantage of the
system is its newness to many farmers."
Good strip intercrops do not
impale parasites on sticky hairs, and have abundant pollen and nectar to fuel
the natural enemy fighting force.
Cotton, corn, cowpea, sorghum, and Crotolaria are among the good strip
crop candidates. Texas experiments show that Trichogramma pretiosum - an egg parasite of bollworm and other
cotton caterpillars that Rincon-Vitova has been selling to cotton growers since
1960 - and many other parasites live several times longer and destroy more
pests when cotton, weeds or other plants provide nectar. Borders of alfalfa,
sorghum, sunflower, corn etc. can also be quite effective, particularly when
flowering, silking etc. are timed to pest life cycles.
In 1935, Marcovitch (J.
Econ. Entomol. 28:62-69) touted strip farming for increasing the
effectiveness of cotton boll weevil parasites: "In planning the cropping
system there can be no possible harm in arranging to have a forage or hay crop
adjacent to the cotton field. In case a forage crop is used, cowpeas, with the
ever-present cowpea pod weevil would undoubtedly bring about the presence of
several important parasites. The early removal of the cowpeas for fodder would
force the parasites to attack the boll weevil." Cutting fencerow weeds led
to highest boll-weevil parasitism in adjoining areas. Other plants harboring
boll-weevil parasites include dewberry, croton and amorpha.
In 1947, Lincoln and Isley (J.
Econ. Entomol. 40(3):437-8), after studying decades of Arkansas bollworm
outbreaks, found that "The bollworm infestations developed when no trap
crop was available." Cotton fields near late silking corn escaped major
damage, as "the ovipositing moths apparently transferred their attention
from cotton to corn and little late infestation of cotton followed. In one
instance where a small planting of late corn, less than 2 acres, was adjacent
to a field of cotton of about 60 acres, the average number of eggs on fresh
silk was over 200 to the ear. Many eggs were also scattered over these corn
plants. In all 15 of these fields, corn was effective as a trap crop and the
infestation of cotton declined sharply with the beginning of silking."
Strip or trap crops can be
the breeding grounds for beneficial arthropod wildlife that migrates, is forced
(e.g. by cutting) or transferred (by D-Vac suction collection) to nearby
cotton.
PUTTING IT ALL TOGETHER
Maintaining biological
control in cotton throughout the season is an ongoing process.
Rincon-Vitova encourages
cotton growers to work closely with PCAs and IPM consultants to create on-farm
insectaries to provide large armies of natural enemies, devise trap crops for
key pests, conserve indigenous beneficial arthropod wildlife through judicious
pest control solutions and inoculate fields with new natural enemies. Since not
all cotton plants or parts of fields get pests at the same time, careful
monitoring and sampling of the progress of biological controls is advised to
identify "hot spots" for treatment with larger numbers of
beneficials. The best PCAs can also adjust economic treatment thresholds
upwards to take into account the fact that fields patrolled by armies of
natural enemies can withstand higher pest populations without showing economic
loss.
It takes from one to three
years to make the transition and grow back the known sets of resident natural
enemies for all pests of vegetable and field crops. But for many growers, it is
worth the effort, as biological control systems based upon natural enemies are
safe, permanent, economical pest control solutions that fit in well with
sustainable farming systems based upon ecological principles.
Rincon-Vitova Insectaries
customers on accounts are informed through periodic mailings of new beneficial
species, some of which are so scarce that only very small quantities can
initially be provided for inoculation. In addition, where demand is sufficient,
we can on special request collect or obtain rarer natural enemies not normally
available commercially.
Technical bulletins are
available for all the beneficials that we sell. A quality control specialist works to insure that the best
possible product is sent out. Nevertheless, sometimes shipments of fragile
insects can arrive injured or otherwise not meet expectations. As we stand
behind all product shipped, please feel free to contact us should you ever feel
that there is a problem or that a replacement may be necessary.