Report by Everett J. Dietrick

This report covers trips with Stefan Long and Francisco Cornejo to monitor all seven cotton production fields of the project. Our goal is to try and develop a report in story form that lists the findings of the important issues as they progress in the seasonal time-line of crop production.

BIOLOGICAL CONTROL (BC) OF COTTON PESTS--NATURAL ENEMY COMPLEX (NEC)

Assessing the progress of natural biological control suppression of pests has not been marketed because pesticides were effective and cheap. Oil was cheap energy that kept the petrochemical industries costs low and profits high. However, perceptions change when energy and pesticide costs increase and the price for marketable cotton is below production costs. It is now prudent to monitor the "good bugs" (beneficial organisms) as they interconnect to suppress their prey, the potential pests (food).

Insects migrate continually into the growing cotton from adjacent fields of the local plantscape (alfalfa, corn, safflower, vegetables, weeds, etc.) As the cotton grows the beneficials reproduce many generations of good and bad insects to add to the population density of the natural enemy complex. As the cotton crop grows it eventually fills all of the space and produces a canopy of plants. The population density of the insects increases but the often the ratio of good and bad bugs remains the same and is still favorable to biological control. More space on the cotton plants as the cotton grows allows for a continuous increase in plant feeding insects and the beneficials that suppress their populations. This is an open-ended, dynamic, biological process that is interconnected with many sets of good and bad bugs as well as resident neutral species that occupy space and compete for food with plant feeders with little or no benefit or harm.

Cotton under biological control has a higher and higher ratio of beneficials than pests as the season advances. Many are simply antagonistic to plant feeding pests. This natural enemy complex (NEC) is best seen in alfalfa hay. Most of the insects emigrate from alfalfa during the mowing process and return when the irrigation starts the plants growing again. Most often there is no damage to alfalfa hay or the cotton and no sprays are needed. The cotton plant can thrive with these insects most of the time. When there is too many of both good insects and pests, a soft or selective control treatment will lower the total density and still retain the good bug/bad bug ratio.

Biological control functions continuously in cotton as the beneficial organisms move from these adjacent fields into the young cotton plantings where they seek food, their particular prey. They will stay put only if sufficient food is present. Broad-spectrum pesticides don't leave enough food (prey) to sustain these increasing numbers of beneficials. "Softer" less effective materials like Bt and sulfur work well if a satisfactory NEC is present. But when the beneficial/pest ratio is unsatisfactory, as when the "hard" pesticides kill all of the NEC insects, good and bad. Ideally, the pesticide should kill more plant feeding pests and less good bugs. Therefore, the damage level for pests is stopped and the beneficials keep increasing and cleaning up future pest populations that are late season pests that are yet to affect cotton like aphids whitefly and worst of all bollworm. These pests will not appear if we protect the NEC.

As the season advances the growth of the cotton plants, the predators and parasites interconnect with potential pest species that are also entering the cotton adjust their numbers to where biological controls predominate. Biological control cotton should have less pests and not more. The unlimited food source provided by the cotton feeds the plant feeding insects from planting through harvest and the good bugs win. It is a common sense way to reduce the use (costs) and increase yields and quality when cotton prices are low. BC IS THE ECOLOGICAL BASIS FOR REDUCING THE NECESSITY FOR PESTICIDE USE.

Natural biological control of cotton pests is happening and it can be made more effective. Understanding the good bug/bad bug ratios is essential to eliminate the fear of insect problems. We want to show you that the only good bug is not a dead bug. Of the estimated 300 to 350 insect and insect like species (arthropods that I will call insects) known to be associated with unsprayed cotton in this area of California, there are only a few that ever increase in numbers to become pests. Many are non-resident species to cotton and are only passing through. The diversity of these insects that have adapted to the way we farm, ranges from soil dweller, scavengers, or fungus feeders, many are predaceous or parasitic, still others feed on the vegetative and fruiting parts of the cotton plant. Others are pollen and nectar feeders, and play a role in pollination. About 20% of these diverse arthropods fall into the plant-feeding category (a total of 60 to 70 species). Surveys that I participated in, during the late 1950s while working for U. C. Department of Biological Control, revealed only 50 of these plant-feeders ever occurred in cotton fields that were located in the agriculture around our experiments along Old River Road.

Despite such a large complex of potentially damaging insects, only about half-dozen are considered to be major pest species and even these do not cause damage at all times and places. Prior to WW2 and DDT, Gordon Smith, cotton entomologist for UC working out of the USDA, Shafter Cotton Research Station told us that cotton was rarely treated; sulfur dusting for patches of web-spinning mites was about all that was needed to grow cotton. Our work in the 1950s led to large reductions in pesticide use after the failure of DDT due to " resistance". These experiments further substantiated the success of natural biological control of cotton pests.

However, cheap effective pesticides continued to replace much of the fear generated when any insect was seen. Mass marketing and endorsement by scientist advocates of chemicals sold DDT and the rest of the chemistries that killed everything. (The only good bug is a dead one became the paradigm). Over-reliance on chemicals has lead to insect resistance to all pesticides. Like drug addiction, the farmscape addiction to pesticide controls has made chemicals ever more costly. It is common sense to want to reduce these costs. Our project is designed for those farmers who are volunteering to participate in this demonstration.

IPM, integrated pest management, has been a giant step in transitioning from conventional chemical control CCC, to more biological control suppressive systems. Fortunately, there are still a few unsprayed cotton fields located among our participating farmers that have an adequate natural enemy complex NEC. We will be examining the insects in these fields at the same time as the insects on other farms and reporting our findings from all fields weekly.

The next step beyond IPM monitoring is being described as ecologically based pest management. The term we are using, EBPM, takes IPM a step further. EBPM seeks to grow back the full diversity of biological control organisms in the refuges for beneficials, the non-market patches of a diversity of "key" plants and crops that can trap and tolerate insects without economic loss, thus enhancing the biological control adjacent to your market crops. We want to try this, when and where it is possible, by providing a diversity of plant habitat enhancement patches. The idea is to have sacrifice plants that attract the pests away from the cotton market crop and use these trapped pest insects to grow more of the beneficials that are a resource of good bugs that move quickly into the cotton. BC organisms are often too few and too late. Refuge plantings are a natural way to enhance the full NEC.

Alfalfa hay is both a resource for pests as well as their natural enemies--a resource for NEC to help cotton. When hay fields mature and are harvested all adult (winged) insects and spiders are forced to find shelter and food in adjacent cotton fields. Lygus is particularly worrisome. There are presently many lygus in the alfalfa that will move at cutting time into cotton and almost immediately (7 to 10 days) back out of cotton as soon as the hay is harvested and watered back. Cotton can sustain low levels of lygus so long as sufficient bolls are setting without damage. The increased plantings of alfalfa in this geographic area will help grow back the trillions of predatory and parasitic insects that used to protect all of California agricultural, particularly in Kern County where one-sixth of the farming was alfalfa was grown for beef. We will be closely monitoring alfalfa that is adjacent to cotton to help predict the movement of these insect populations in relation to cotton.

The May 20 samples revealed low populations of all pests in the very young cotton plants with a high ratio of predators--big-eyed bugs (Geocoris pallens and G. punctipes, hooded beetles Notoxis, ladybugs, damsel bugs Nabis spp., green lacewings Chrysoperla spp., assassin bugs Sinea and Zelus spp. The density of these predator populations was low. (See the pictures and descriptions of the roles these insects play in the NEC). There were very few pests on the small cotton plants to attract them at this time. Competition for food (prey and host species) drives the predators into the cotton. Cabbage loopers Trichoplusia ni. a leaf feeding worm in cotton was the main food in one area at one farm. Some leaf feeding occurred. It appears that the Round-Up herbicide treatment killed many loopers. There were fewer predators May 24 than May 31 which suggests the insect for alfalfa replaced any that were not present following the treatment prior to May 24 samples. This alfalfa field that will soon be harvested is full of beneficials as well as many adult moths of cabbage loopers, fewer numbers of bollworm and beet armyworm moths and yellow-stripped armyworms.

Big-eyed bug Geocoris pallens spends time on the ground and likes to search for prey on young cotton plants. G. punctipes is more prevalent when the cotton plants form a canopy.

The second most important predators are the damsel bugs, Nabis spp.

The third and more common predator is a beetle called the hooded beetle, Notoxis sp. Anthicidae that overwinters as an immature larva in soil protecting plant roots. The adults are emerging from grains-- a predator of thrips and stinkbug eggs.

Minute pirate bug, Orius spp. is in the alfalfa hay where its favorite host—the thrips--are.

All of these beneficial insects are generalist predators that will attack any small worm. Cabbage looper eggs and larvae Trichoplusia ni, a cotton leaf worm are being attack now.

Other "key" insects observed. Hyposoter exiguae, a #1 parasite of bollworms, beet armyworms, cabbage loopers and other worms were sampled. 60 percent parasitism of half-inch worms has been recorded by this parasite on occasion.

All spiders seek insects for food. Crab spiders (Thomisidae) and wolf spiders Pardosa spp. are entering cotton by ballooning on webs from alfalfa into cotton. Crab spiders attack lygus and wolf spiders seek all kinds of prey at night.

Ground beetles, immature larvae of possibly, the black ground beetle Calosoma affinae were seen running on the ground between safflower and cotton at one farm. They devour large worms in cotton, live several years feeding mostly at night. (The sun was setting when we saw large numbers.)

East Bakersfield Farms: Biological control enhancement trap crop patches of plants were planted where irrigation and soil moisture was happening at both farms. Sudan grass seed was delivered to those cooperators who would agree to plant a barrier against road dust and infrared radiation. This plant is a refuge for green lacewing adults (the best aphid and spider mite predator, the larva of which is known to seek prey reaching greater distances (one estimate of one mile covering many plants) than all other mite predators. There are many overwintering adult lacewings in the alfalfa and other plantings that are beginning to lay their eggs in the young cotton plants. They will eat eggs and small cotton worms as well. The patches of corn plants that we plant are useful to attract lacewings. They seek the pollen and moisture (plant exudate common to corn and Sudan) where they hang out during the day, flying like butterflies from evening until they seek shelter again from the hot sun. Hundreds can be seen during the day in sunflowers, Sudan, and corn, safflower etc.. They lay their eggs everywhere during the night. It is not too late to benefit from planting the Sudan seed although I wish that it was already growing.

One of the East Bakersfield farms is right across the street from the check field, where the highest populations of cabbage loopers occurred. This cotton is interplanted with corn and melons and has the high ratio of good bugs to pests in all our samples. We think it is because of diversity of plants in this cotton field. There was little to no damage from the cabbage looper leaf worms. It is apparent that the resident predators in the cotton are destroying the looper eggs and day old worms as fast as they are laid, whereas the damage occurring across the road came from the lack of any of these resident natural enemies across the street. When the moths fly they lay their eggs everywhere. Since moth eggs and even some small worms do not damage cotton, where they are immediately eaten there is no damage. Where there is no resident NEC there is no biological suppression. Damage comes when all the eggs laid GROW to be full-grown worms in this enemy-free space. SUCH FIELDS THAT HAVE TOO FEW BENEFICIALS HAVE TO BE TREATED BY CHEMICALS.

Sanders’ Farm: At the Sanders cotton field we have planted a wider dust barrier of a more diverse set of plants that will act as a long-term aid in the control of whitefly. 600 feet of drip hose will keep it irrigated and attractive year round to sustain the whitefly and the permanent residence of the their parasites as well as the predators, Eretmocerus and Encarsia spp., green and brown lacewings, ladybugs etc. Green lacewings are very good predators of whitefly as well as aphids and they are resistant to all pesticides. Therefore, they have become the most important predators, although it appears that other species of beneficials are also tolerant of many pesticides that have been in general use for years. This is a proactive program to grow back the diversity of plants and insects that function in successful ecologically based pest management, EBPM.

A farm near Sanders has less happening but this farming area has little if any pesticide interference effects on the natural enemy complex. The wheat is being harvested and the hooded beetles (Anthicids) and Collops predators of stinkbugs as well as predators of Diabrotica beetles (cucumber beetles or corn root worm larvae that reside in the soil. They are moving into the Pima cotton following the pests.

Biological control is present: Other good news to report is the total lack of aphids, thrips and mites at this time. The numbers of predators relative to prey is suppressing these pests, particularly the hooded beetles, the big-eyed bugs and ladybugs are probably responsible. Adult green lacewings are coming out of winter diapause and starting to reproduce more rapidly. These predators favor thrips aphids and lygus, respectfully, but the only prey in the cotton is looper eggs and tiny worms, so they must eat loopers.

The not so good news is the near absence of beneficial flies. The sampling of the NEC thus far seems to be lacking in beneficial Tachinid fly parasites. We think this is correlated with the very low level of flowering plants that provide pollen and nectar to the adults. We have observed them to fly to and from flowers to their host pests. The wasp parasites are somewhat affected by the lack of blossoms, but the Tachinid flies are the largest and most diverse sets of parasites in unsprayed cotton. They absolutely need year round sources of flowering plants to function at their maximum. The alfalfa and the cotton will soon be flowering, but it is a late start for these important tachinid flies. They will come along later when blooms increase. Alfalfa is now a monoculture with no flowering weeds. The demonstration of habitat at Sanders will show this to be the case when we can get the flowers to bloom. Wild sunflowers serve this role where they are tolerated as weeds that have lots of blossoms.

We look forward to working with the growers on the project: We thank you for the cooperation and the opportunity to investigate implementation of ecologically based pest management, EBPM, on your farms. We will write about what we find and try to suggest possible ecologically-based, small modifications to your farming methods. There is no right way, since Mother Nature has so many ways of accomplishing these natural processes. It comes down to what will work dependably. This is the dawn of the age of life-sustaining systems and sustainable agriculture.