plete. (A more detailed explanation of the ences in mean eggs per hen housed were ob- controlled feeding failed. It could not be mechanics of how feeding time was con- served among controlled feeding methods. determined whether the drop in production trolled can be found in Progress in Poultry Feed savings as a result of the controlled associated with the delayed treatment re- (PIP), issue No. 11 (August 1978), from methods tested were offset by depressed egg sulted from a stress caused by adjustment Cooperative Extension, University of Cali- production, resulting in no significant im- to the controlled feeding method, stress fornia, Riverside, CA 92521.) The diet fed provements in feed efficiency. It follows caused by late Marek’s disease, or the com- to all treatment groups was a standard lay that the lack of improved efficiency pre- bined effects of both. Since the group, mash formulated to contain 17 percent vented potential economic gain over the placed on controlled feeding starting at 22 crude protein and 1260 kilocalories of me- free access feeding method. weeks, suffered a relatively severe produc- tabolizable energy per pound of ration. The experiment was further complicated tion loss (compared with the free access All controlled feeding groups consumed by what was tentatively diagnosed as late control group), it appeared the controlled significantly less feed than the free access Marek’s disease. A characteristic drop in feeding method used imposed some addi- control birds (table 1). As expected, the production was first observed at 34 weeks tional “stress” unrelated to nutrient intake. group controlled starting at 22 weeks of age of age in all treatment groups. This was be- In summary, the controlled feeding consumed less feed than those birds con- fore initiation of the delayed controlled method tested (time-limited feeding) appar- trolled from 40 weeks on. Regarding total feeding treatments. Hen-housed mortality ently stressed the layers to the point where protein and the essential amino acids lysine, rose to approximately 2 percent per month. their ability to resist other stresses, such as methionine, and cystine, more than the re- The birds with free access to feed suffered disease, was impaired. It is believed that quired nutrient levels was achieved by production losses near 12 percent; the losses chickens, when subjected to controlled birds under each of the controlled feeding were only partially regained within 8 weeks. feeding by the time-limited method, toler- programs (table 2). Egg production was A drop in egg production was again ob- ate adjustment better at a young age when depressed by all controlled feeding treat- served when controlled feeding was imple- production rates are low. ments (by 16 to 19 eggs per hen) over the mented at 40 weeks of age. Efforts to Douglas Kuney is Staff Research Associate and Milo Swanson is Extension Avian Scientist, U.C. Cooperative 40-week experiment. No significant differ- minimize this drop by gradually imposing Extension, Riverside.

TABLE 1. Treatment Effects on Feed Consumption TABLE 2. Average Nutrient Intakes throughout 4O.Week Experiment. and Egg Production during 40 Weeks of Lay. Methionine Metabolizable Feed consumption Egg production Treatment Protein Lysine + cystine energy lb1100 Iblavg. % hen eggslhen (9) (m9)’ (mg)’ (Kcal) housed Free access 19.9 796 690 324 Treatment henslday hen day 22-week sudden 17.9 714 620 292 Free access 25.7a‘ 71.9’ 78.7a’ 195a’ 40-week sudden 18.7 748 649 306 22-week sudden 23.2~ 64.9~ 72.4b 179b 40-week gradual 18.2 728 631 297 40-week sudden 24.3b 68.lb 74.513 178b ‘Stated nutrient requirements for Leghorn layers are 660 mg lysine per hen 40-week gradual 23.6bc 66.2bc 74.5b 176b per day and 550 mg methionine plus cystine per hen per day. Nutrient Re- ‘Means within a column with different letters are significantly different quirements of Poultry, 7th ed., 1977. National Academy of Sciences, fPG0.05). Washinaton. D.C.

The naval orangeworm (NOW), ~m- yelois transitella (Walker), is a major insect pest in California orchards. Pesti- Spider and predators cides used to control NOW include Guthion (azinphosmethyl), Imidan (pro- in San Joaquin Valley late), and Sevin (carbaryl). Growers fear that spider increases will occur after these chemical treatments, and Guthion ap- almond orchards parently caused increases in European red mite ( ulmi Koch) populations in two almond orchards near Modesto dur- ing 1977, but no serious problems occurred Marjorie A. Hoy 0 R. T. Roush after use of Sevin in adjacent blocks in these orchards. Katherine B. Smith 0 Les W. Barclay The project reported here was under- taken to determine the types of spider mites, their predators, and their relative importance in southern San Joaquin Valley Natural enemies of spider mites can vary from almond orchards, and to compare them with northern San Joaquin Valley orchards orchard to orchard and from section to section monitored during 1977. We also evaluated in California. the effect of Sevin on Pacific spider mites and their predators in one of these southern almond orchards during 1978. In 1978 almond orchards near Bakers- field, Blackwell’s Corner, and Chowchilla were monitored for mites every two weeks

CALIFORNIA AGRICULTURE, OCTOBER 1979 11 the season. Thus, in these unsprayed almond orchards, M. occidentalis was Orchard Location and Year present on the trees early in the season along with its prey and remained numerous through the season (figures 1,2,3, and 4). 1977 M. occidentalis was an effective predator Yuba City No Wheatland No of spider mites in the Blackwell’s Corner Stockton-Hwy 132 No and Bakersfield almond orchards The Modesto-Whitmore Ave. No abrupt decline of Pacific spider mites in Modesto-Hwy 99 No 1978 July and their subsequent increase in Chowchilla LO August (figures 1, 3 and 4) at the Black- Bakersfield-Hwy99 Med Blackwell’s Corner No well’s Corner orchard is probably because of the predation of M. occidentalis as no insect predators were observed at this time in sufficient quantities to account for the decline in Pacific mites. Sevin was applied for NOW control in Orchard Location one block at the Blackwell’s Corner and Year Brown Siethoru: orchard and it killed many M. occidentalis. An outbreak of Pacific spider mites subse- quently occurred (figure 4), causing appre- YubaCity No Lo No Hi Lo Med Wheatland No Lo No Hi Lo Med ciable leaf fall. Trees untreated in the same Stockton-Hwy 132 No Lo NO Hi LO No block (figure 3) had low levels of Pacific Modesto-Whitmore Ave. LO Lo No LO Hi LO mite, and M. occidentalis was their control Modesto-Hwy 99 LO Lo LO LO Hi LO agent. None of these trees were treated with an acaricide. The Pacific mite outbreak can be attributed to the lethal effects of Sevin on M. occidentalis, but the possible physio- logical stimulation of Pacific mite repro- Med = moderate numbers collectedlobsetved. duction by Sevin cannot be excluded as a Lo = few collectedlobsetved. No = none collected/observed. contributing factor as well. Conclusions from early April until early September. (Tetranychus pacificus McGregor), some Leaf samples consisting of 30 leaves per twospotted spider mites (T. urticae Koch), The combination of spider mites and tree were taken from 18 individually- some Atlantic or “strawberry” mites (T. predators found in southern San Joaquin marked Nonpareil trees in these three turkestani (Ugarov and Nikolski)), and a Valley almond orchards differs from that orchards in blocks in which no acaricides few citrus red mites including P. citri found in the northern part of the valley. or insecticides were applied during 1978. (McGregor). Only a few silver mites From Yuba City to Bakersfield there is a Leaf samples consisting of 50 leaves were (Aculus cornutus (Banks)) were found in gradual change in composition, and also taken in June, July, and August from these more southern orchards. integrated pest management programs or six check and six treated trees in a block Natural enemies found also varied from sampling schemes for mites in where Sevin was applied on July 23 for orchard to orchard and presented a differ- must take this into account. For example, NOW control in the Blackwell’s Corner ent pattern from that observed in the brown mites, which move from leaves to orchard. Leaf samples were kept cool until northern orchards (table 2). Metaseiulus twigs, must be sampled differently than the total number of mites per leaf (all (= Typhlodrornus) occidentalis (Nesbitt) species that remain on leaves. The effect of stages, including eggs) were counted under was the dominant phytoseiid predator in these different species upon a dissecting microscope. Male spider mites the Chowchilla, Bakersfield, and Black- almonds is not known. collected throughout the season were well’s Corner almond orchards during Predators such as green lacewings, mounted on slides and identified as to 1978. Other spider mite predators found Stethorus beetles, and sixspotted thrips species. General insect predators were included the sixspotted thrips (Scolothrips were common in most of these unsprayed assayed by counts of eggs, larvae, nymphs sexmaculatus Pergande), Stethorus beetles, orchards. Such predators, no doubt, affect or pupae on the samples, and a 10-minute and green lacewings. In contrast, M. occi- spider mite populations, although this is visual assay was made in each orchard on dentalis was found in two of the northern difficult to assess because of difficulties in sample dates. orchards in 1977, but was much less effec- sampling these insects. The predatory mite tive in the northern almond orchards. M. occidentalis, was found in four of the Results In the Bakersfield and Blackwell’s eight orchards monitored in 1977 and 1978. Spider mite species and their relative Corner orchards, M. occidentalis was In two of these orchards (Bakersfield and abundance varied from orchard to orchard found early in April feeding on Pacific Blackwell’s Corner), M. occidentalis (table 1). Unlike the situation in northern spider mite females and eggs which were on dramatically reduced Pacific spider mite California almond orchards in which Euro- newly-expanded foliage. This suggests that populations. In the other orchards, Euro- pean red mite and brown mite (Bryobia zither M. occidentalis overwintered on the pean red mite was the dominant spider mite rubioculus (Scheuten)) were common, these almond trees (as it does on trees), and M. occidentalis appeared to be less ef- southern San Joaquin Valley orchards had perhaps in bark crevices, or that M. occi- fective against this pest. The importance of large numbers of Pacific spider mites dentalis was able to enter the tree early in M. occidentalis in other almond orchards is

12 CALIFORNIA AGRICULTURE, OCTOBER 1979 . BLACKWELL’S BID ART - UNTREATED CORNER. UNTREATED - T oacificue

40

30

c m -W 10 L 0) a

in W e- E 10

2, (I 22 8 21 5 11 3 9 28 ’9 AM J J A S

Figure 2. Mean numbers of citrus red mite, all Tetranychus 21 0 23 I 22 (I 18 1 0 23 0 spp., and M. occidentalis (x 10) per leaf in the untreated Bakers- AM J J A S field (=Bidart) orchard, 1978. “All spider mites” are pooled counts of P. citri and Tetranychus spp. Figure 1. Mean numbers of Pacific spider mites per leaf and mean numbers of M. occidentalis per leaf x 10 in an untreated almond orchard, 1978. All stages, including eggs, are counted.

SO

BLACKWELL S CORNER SEVIN TEST UNTREATED

~T~acitlcw

40 llll.l.ll M occidentalis x 10

30

c m a, 20

L 0 a

in W .-

10

Figure 4. Mean numbers of Pacific mites per leaf and mean Figure 3. Mean numbers of Pacific spider mites per leaf and numbers of M. occidentalis x 10 after Sevin treatment, 1978. No mean numbers of M. occidentalis x 10 on untreated check acaricide was applied and defoliation caused a Pacific mite trees, 1978. All stages, including eggs, are counted. decline. All stages, including eggs, are counted.

Marjorie A. Hoy is Assistant Professor and Assistant not known, but the effects of Sevin in the This is the first time that M. occidentalis Entomologist, Department of Entomological Sciences, U.C., Berkeley. R. T. Roush and Katherine B. Smith Blackwell’s Corner orchard indicate that has been shown to be an important preda- are Graduate Students there. Les w. Barclay Is staff insecticide treatments for NOW can disrupt tor of spider mites in almonds, although its Research Assoc*ate, u.c COOPerative rixtension, Bakersfreld This research was supported in part by a M. occidentalis control of sDider mites and imDortance as a spider mite predator is well prant from the Almond Board of Callforma The therefore necessitate treatments with known in grapes, , pears, , authorstheir orchards, wish andthank C. theS. Davis,almond Wilburbrowersfor 0. Reiluse and Of acaricides. and walnuts in California. Toynette W. Johnson for assistance in theproject.

CALIFORNIA AGRICULTURE, OCTOBER 1979 13