Alternative plant habitats for common phytoseiid predators of the cassava green mite (Acari: Phytoseiidae,Tetranychidae) in northeast Brazil

A survey was conducted to identify possible alternative plant habitats of the most common phytoseiid predators associated with the cassava green mite, Mononychellus tanajoa (Bondar), in their native environment in northeast Brazil. Thirty-two phytoseiid species were collected, including Amblyseius aripo (DeLeon), Amblyseius idaeus (Denmark and Muma) and Amblyseius limonicus Garman and McGregor s.l., the three predators previously shown as the most common on cassava. In increasing order, A. idaeus, Phytoseius guianensis DeLeon and A. aripo were the most common phytoseiids collected on the plant habitats examined. A. limonicus s.l. was one of the least common phytoseiids on plants other than cassava. Altermative plant habitats seem important in harboring A. aripo and A. idaeus, but not A. limonicus s.l..     

Establishing insecticide-resistant phytoseiid mite predators in deciduous tree fruit orchards

A summary of basic biological, ecological and toxicological characteristics of 3 phytoseiid mite predatorsTyphlodromus occidentalis Nesbitt,Amblyseius fallacis Garman andTyphlodromus pyri Scheuten which have developed resistances to certain insecticides commonly used in commercial fruit orchards is presented. Methods of culturing and mass-rearing these mites are reviewed. Also the cultural and pesticidal measures which should be maintained to facilitate effective biological control of spider mite pest of deciduous fruit crops by these predators and to maximally provide for their establishment in areas of the world where resistance has not developed or they do not occur naturally are discussed.

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Résumé L'auteur résume les caractéristiques fondamentles biologiques, écologiques et toxicologiques de 3 phytoséiides prédateurs d'acariens,Typhlodromus occidentalis Nesbitt,Amblyseius fallacis Garman etTyphlodromus pyri Scheuter, qui ont acquis une résistance à certains insecticides généralement utilisés dans les vergers de fruits commerciaux. Les méthodes d'élevage et de multiplication massive de ces acariens sont rappelées. Sont également discutées les techniques culturales et phytosanitaires qui sont à employer pour favoriser ces prédateurs comme agents de lutte biologique efficace contre les acariens nuisibles aux vergers et pour procéder à leur implantation dans les régions du monde où la résistance ne s'est pas manifestée ou bien où ces prédateurs n'existent pas naturellement.

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This publication was supported in part by a NSF-EPA grant GB-34718 to the University of California. The findings, opinions and recommendations expressed herein are those of the author and not necessarily those of the University of California, NSF or EPA. Published as Journal Article N. 1559 of the Michigan State University Agricultural Experiment Station.     

Saturation deficit tolerance spectra of phytophagous mites and their phytoseiid predators on cassava

In South America, phytophagous cassava mite populations reach high densities during the dry season but occur in low numbers during the rainy season. Some of their phytoseiid predators, however, show the reverse pattern. We test the hypothesis that this different seasonal phenology can be attributed to distinct saturation deficit tolerance spectra. Eggs of various species c.q. strains of phytoseiids, orginating from different climate zones, were screened for their tolerance to a range of saturation deficits and compared with the tolerance spectrum of tetranychid species collected from cassava. In total 19 species/strains of predatory mites were compared with six tetranychid species. The response curves for all predators were sigmoidal with a narrow and specific region of saturation deficits where egg hatch success fell from 100% to 0%. Using probit analysis this region was characterized by the SD₅₀, the saturation deficit at which only 50% of the eggs hatch. The response curves for the herbivores were trapezoid. In contrast to the phytoseiids the latter do not differ in the range of saturation deficits tolerated, but in the magnitude of the response.It appeared that inter-strain differences in the Phytoseiidae are sometimes larger than interspecific differences. We demonstrate that there is a significant correlation between population-specific SD₅₀-values and long term average relative humidity in the collection site. The implications of this finding are discussed in terms of condition specific competition.     

An artificial diet for rearing the phytoseiid mite,Amblyseius teke Pritchard and Baker

Several diets for rearingAmblyseius teke were developed and tested. Of these, the liquid diet ICD 286, based on commercial bee honey, milk powder, egg yolk, Wesson's salt and water proved the most promising. Twenty-five generations have been completed so far.     

中国植绥螨规模化饲养及保护利用研究进展

根据植绥螨食性的不同 ,可以采用叶螨、花粉和人工饲料等食物来培养植绥螨。规模化饲养植绥螨多用叶螨等害螨的寄主植物先繁殖害螨 ,然后在害螨中加入一些补充食物来大量生产植绥螨。张艳璇设计的袋栽法就是这样一套新的大量繁殖植绥螨的工艺方法。植绥螨的贮存目前都采用降低发育来实现 ,一般在 5～ 1 0℃的温度下能保存 5 0d以上。在田间按一定的比例释放抗药性的植绥螨 ,能够有效的控制二斑叶螨TetranychusurticaeKoch等害螨的发生。并且在地面鼓励种植覆盖作物、允许少量杂草生长或实行生草栽培 ,能够为植绥螨提供交替食物 ,从而更好地发挥生态控制功能的作用。     

Prey consumption by phytoseiid spider mite predators as affected by diurnal temperature variations

The consumption rate of an ectothermic predator is highly temperature-dependent and is a key driver of pest-predator population interactions. Not only average daily temperature, but also diurnal temperature variations may affect prey consumption and life history traits of ectotherms. In the present study, we evaluated the impact of temperature alternations on body size, predation capacity and oviposition rate of the predatory mites Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus McGregor (Acari: Phytoseiidae) when presented with eggs of their natural prey, the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae). For both predators, mean daily temperature as well as temperature alternation had a substantial impact on the number of prey consumed. At lower average temperatures, more eggs were killed under an alternating temperature regime (20 °C/5 °C and 25 °C/10 °C) than at the corresponding mean constant temperatures (15 and 20 °C). At higher average temperatures (>25 °C), however, the opposite was observed with higher numbers of prey killed at constant temperatures than at alternating temperatures. At 25 °C, temperature variation had no effect on the predation capacity. A similar trend as for the predation rates was observed for the oviposition rates of the phytoseiids. Body size of N. californicus was affected both by average daily temperature and temperature variation, with smaller adult females emerging at alternating temperatures than at constant temperatures, whereas for P. persimilis, temperature variation had no impact on its body size. Our results demonstrate that temperature variations are likely to affect biological control of T. urticae by the studied phytoseiid predators.     

Host specificity of the cassava green mite pathogen Neozygites floridana

Tests were conducted on the hostspecificity of a Brazilian isolate of thefungus Neozygites floridana, a potentialbiological control agent for the cassava greenmite, Mononychellus tanajoa, in Africa.Five insect and two mite species, mostly fromthe cassava agroecosystem, were evaluated forsusceptibility to N. floridana, namelyEuseius concordis, E. citrifolius, Phenacoccus herreni, Stethorus sp., Aleurothrixus aepim, Apoanagyrusdiversicornis, and Bombyx mori.Individuals of each species were exposed tocapilliconidia (the infective stage of thefungus). None of the tested individuals wasfound with hyphal bodies (the vegetative stageof the fungus), whereas 73 to 94% of thecassava green mites in the controls becameinfected. Non-germinated capilliconidia were,however, found attached to several individualsin most species. N. floridana appears tobe safe for exportation. Further evaluation ofits performance against M. tanajoa inAfrica is therefore desirable.     

Effects of prey mite species on life history of the phytoseiid predators Typhlodromalus manihoti and Typhlodromalus aripo

The effects of prey mite suitability on several demographic characteristics of phytoseiid predators and the relationship of these effects to the potential of phytoseiid predators to control herbivorous mite populations are well documented. Evidence has also accumulated in the last 20 years demonstrating that phytoseiid predators utilize herbivorous prey mite-induced plant volatiles as olfactory cues in locating their herbivorous mite prey. but less well established is the predictability of reproductive success from the ability of the predators to utilize olfactory cues to locate their prey, and how these processes are related to the success of the predators as biological control agents of the herbivorous mite. In this study, we determined in laboratory no choice experiments, the development, survivorship and fecundity of the two neotropical phytoseiid predators Typhlodromalus manihoti Moraes and T. aripo DeLeon when feeding on three herbivorous mites, including the key prey species Mononychellus tanajoa (Bondar), and the two alternative prey species Oligonychus gossypii (Zacher) and Tetranychus urticae (Koch). Intrinsic rate of increase (rm) of T. aripo was 2.1 fold higher on M. tanajoa as prey compared with T. urticae as prey, while it was almost nil on O. gossypii. For T. manihoti, rm was 2.3 fold higher on M. tanajoa as prey compared with O. gossypii as prey, while reproduction was nil on T. urticae. An independent experiment on odor-related prey preference of the two predator species (Gnanvossou et al. 2002) showed that T. manihoti and T. aripo preferred odors from M. tanajoa-infested leaves to odors from O. gossypii-infested leaves. Moreover, both predator species preferred odors from M. tanajoa-infested leaves over those from T. urticae-infested leaves. As reported here, life history of the two predatory mites matches odor-related prey preference if the key prey species is compared to the two inferior prey species. The implications of our findings for the persistence of T. manihoti and T. aripo and biological control of M. tanajoa in the cassava agroecosystem in Africa are discussed.     

Bionomics ofEotetranychus tiliarium and its phytoseiid predators

Under urban conditions,Eotetranychus tiliarium (Hermann) frequently develops into high population densities onTilia lining streets, in contrast to its development in natural habitats and on park trees. In mixed forest and on park trees, a regulating system precludes these outbreaks. In an earlier study it was shown that a change in the predacious mite species composition, leading to displacement of the most effective predator species by less effective ones, is the main reason for this phenomenon.The bionomics ofE. tiliarium on its host plantTilia spp. in various habitats were studied as well as the characteristics of the predacious mites which determine their potential for preventing spider-mite outbreaks.Predacious mites from the family Phytoseiidae were able to preventE. tiliarium outbreaks.Paraseiulus soleiger was the most effective predacious mite species, because it has a short development period, a long period of longevity, a long oviposition period, and has a clear preference forE. tiliarium and a high prey-consumption capacity. Eotetranychus tiliarium onTilia lining streets has a greater potential for increase than the spider mites from park trees and from forest trees. The nutritive value of leaves on trees in street habitats is increased by the increased salt content in the soil from snow control in winter. Also, the higher temperatures in urban conditions may stimulate population development.     

Continent-wide releases of neotropical phytoseiids against the exotic cassava green mite in Africa

Since the initiation of the classical biological control campaign by the International Institute of Tropical Agriculture to control the exotic mite, Mononychellus tanajoa, 11 species (18 distinct populations) of neotropical phytoseiids have been selected and shipped to Africa for experimental releases. Initially, natural enemies were selected because of their abundance and frequency on cassava. Between 1984 and 1988, more than 5.2 million phytoseiids belonging to 7 species of Colombian origin were imported to Africa and released in 348 sites in 10 countries. None of these species and populations ever became established in the wide range of agronomic and ecological conditions tested, apparently because of inadequate alternative food sources when M. tanajoa densities were low and extended periods of low relative humidity. Foreign exploration was adjusted in 1988 to focus on Neotropical regions that were agrometeorologically homologous to areas in Africa where the potential for severe M. tanajoa damage exists. Natural enemies associated temporally and spatially with M. tanajoa and capable of surviving periods of low M. tanajoa densities on alternative food sources in the new exploration sites were given selection priority. Several natural enemy candidates were immediately identified in Northeast Brazil and shipped to Africa. Approximately 1.9 million phytoseiids of the species Neoseiulus idaeus and Typhlodromalus limonicus of Brazilian origin were released in 133 sites in 6 countries in 1989 and 1990. N. idaeus has since become established in Benin, while T. limonicus may be established in Benin, Burundi, and Ghana.     

Effects of prey mite species on life history of the phytoseiid predators Typhlodromalus manihoti and Typhlodromalus aripo

The effects of prey mite suitability on several demographic characteristics of phytoseiid predators and the relationship of these effects to the potential of phytoseiid predators to control herbivorous mite populations are well documented. Evidence has also accumulated in the last 20 years demonstrating that phytoseiid predators utilize herbivorous prey mite-induced plant volatiles as olfactory cues in locating their herbivorous mite prey, but less well established is the predictability of reproductive success from the ability of the predators to utilize olfactory cues to locate their prey, and how these processes are related to the success of the predators as biological control agents of the herbivorous mite. In this study, we determined in laboratory no choice experiments, the development, survivorship and fecundity of the two neotropical phytoseiid predators Typhlodromalus manihoti Moraes and T. aripo DeLeon when feeding on three herbivorous mites, including the key prey species Mononychellus tanajoa (Bondar), and the two alternative prey species Oligonychus gossypii (Zacher) and Tetranychus urticae (Koch). Intrinsic rate of increase (r_m) of T. aripo was 2.1 fold higher on M. tanajoa as prey compared with T. urticae as prey, while it was almost nil on O. gossypii. For T. manihoti, r_m was 2.3 fold higher on M. tanajoa as prey compared with O. gossypii as prey, while reproduction was nil on T. urticae. An independent experiment on odor-related prey preference of the two predator species showed that T. manihoti and T. aripo preferred odors from M. tanajoa-infested leaves to odors from O. gossypii-infested leaves. Moreover, both predator species preferred odors from M. tanajoa-infested leaves over those from T. urticae-infested leaves. As reported here, life history of the two predatory mites matches odor-related prey preference if the key prey species is compared to the two inferior prey species. The implications of our findings for the persistence of T. manihoti and T. aripo and biological control of M. tanajoa in the cassava agroecosystem in Africa are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Feeding behavior of some phytoseiid predators on the broad mite,Polyphagotarsonemus latus [Acari: Phytoseiidae,Tarsonemidae]

Feeding behavior of 4 phytoseiid species on the broad mitePolyphagotarsonemus latus (Banks) was studied.Typhlodromus rickeri Chant,T. porresi McMurtry, andT. annectens DeLeon preferred prey larvae over other stages.Euseius stipulatus Athias-Henriot fed on all but the nymphal stage, and showed a decreased preference for prey larvae and females. None of the 4 species fed upon the nymphal stage.

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Résumé Le comportement alimentaire de 4 espèces dePhytoseiidae surPolyphagotarsonemus latus (Banks) a été étudié.Typhlodromus rickeri Chant,T. porresi McMurtry, etT. annectens DeLeon préfèrent les larves de la proie aux autres stades.Euseius stipulatus A.-H. s'alimente sur tous les stades de la proie sauf la nymphe, mais les larves et les femelles de la proie sont moins appréciées. Aucune des 4 espèces ne s'est alimentée aux dépens du stade nymphal.

     

Effects of the entomopathogenic fungus Neozygites tanajoae and the predatory mite Typhlodromalus aripo on cassava green mite densities: screenhouse experiments

To improve biocontrol of the cassava green mite, Mononychellus tanajoa, a series of screenhouse experiments were conducted on cassava to determine the effects of single and combined releases of the predatory mite Typhlodromalus aripo and the entomopathogenic fungus Neozygites tanajoae on the suppression of M. tanajoa. We showed that, separately or in combination, T. aripo and N. tanajoae significantly reduced M. tanajoa populations. Moreover, combined release of T. aripo and N. tanajoae on the same cassava plants improved M. tanajoa control. However, our data suggest between T. aripo and N. tanajoae an asymmetric competition that significantly affected N. tanajoae only. This interference is indirect, probably mediated by their common prey or host mite, M. tanajoa since N. tanajoae is not pathogenic to T. aripo. We conclude that adding N. tanajoae to T. aripo populations in Africa would not negatively affect T. aripo and would further promote biocontrol of M. tanajoa.     

Diet-dependent cannibalism in the omnivorous phytoseiid mite Amblydromalus limonicus

Amblydromalus limonicus (Garman & McGregor) (Acari: Phytoseiidae) is a commercially available predator of key pests in protected crops, particularly of thrips and whiteflies. Basic information on the developmental and reproductive performance of the predator as a function of food is largely lacking. In the present study, development, reproduction and growth rates were determined for A. limonicus on four economically important pests: Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae), broad mite, Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae) and two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). The life history traits of females fed on these different target prey were compared with those of females offered Carpoglyphus lactis L. (Acari: Carpoglyphidae), which is the standard food source for mass-producing this predator. Additionally, three commercially available non-prey food sources with potential for use in the mass production or as supplementary food to sustain populations of the predator in the field were tested: the commercial pollen product Nutrimite (consisting of pollen of narrow-leaved cattail, Typha angustifolia L.), frozen eggs of the Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) and frozen eggs of the Mediterranean fruit fly, Ceratitis capitata Wiedemann (Diptera: Tephritidae). Survival rates of immature A. limonicus were high (>94% survival) on all tested foods except on T. vaporariorum and T. urticae (76.0% and 17.1%, respectively). The fastest development was obtained when mites were fed on T. angustifolia, whereas the longest developmental times were obtained on T. urticae and T. vaporariorum. When females were offered P. latus, no reproduction was observed, despite a high prey consumption in both the juvenile and adult stages. The reproductive performance of A. limonicus fed on T. vaporariorum was significantly lower than that on F. occidentalis. Furthermore, no second generation could be obtained on a diet solely consisting of T. vaporariorum. Population growth rates were highest when A. limonicus was fed on Nutrimite, E. kuehniella or C. lactis, and exceeded those on a diet consisting of their natural prey, F. occidentalis. The phytoseiid showed cannibalistic behavior when maintained on E. kuehniella and C. capitata eggs and T. angustifolia pollen, with females consuming their own eggs. The rate of cannibalism was dependent on the food source offered, but always resulted in reduced population growth rates. This cannibalistic behavior should be taken into account when selecting food sources for mass rearing of A. limonicus or supporting its populations in the field.     

Within-season dynamics of red palm mite (Raoiella indica) and phytoseiid predators on two host palm species in south-west India

Field surveys were conducted monthly between December 2008 and July 2009 in Kerala, south-west India to compare the population dynamics of the red palm mite Raoiella indica (RPM) on two host plants Areca catechu and Cocos nucifera during one non-monsoon season when, in general, RPM populations increase. The aim was to examine the effects of host plant, host plant locality and the impact of climatic factors on RPM and related phytoseiid predators. There were significantly higher RPM densities on areca in peak season (May/June) compared to coconut; although significantly more coconut sites were infested with RPM than areca. Although no one climatic factor was significantly related to RPM numbers, interactions were found between temperature, humidity and rainfall and the partitioning of host plant locality showed that where conditions were warmer and drier, RPM densities were significantly higher. Specifically on coconut, there was a significant relation between RPM densities and the combined interaction between site temperature, site humidity and phytoseiid densities. There was a marked difference in the density of phytoseiids collected between areca and coconut palms, with significantly more on the latter, in several months. Amblyseius largoensis was the most commonly collected phytoseiid in association with RPM, although Amblyseius tamatavensis species group and Amblyseius largoensis species group were collected in association with RPM also. There was also evidence of a weak numerical response of the combined phytoseiid complex in relation to RPM density the previous month on coconut but this was not observed on areca.     

Effect of mass rearing on the genetic diversity of the predatory mite Amblyseius swirskii

Amblyseius swirskii Athias‐Henriot (Acari: Phytoseiidae) is a predatory mite used to control whiteflies and thrips in protected crops. This biocontrol agent, originating from the Eastern Mediterranean region, has been mass‐reared for commercial use since 2005 and is widely used in augmentative biocontrol programs. As a polyphagous predator, it has to cope with different biotic and abiotic factors. However, possible adaptation to mass rearing for production might be hindering its resilience and capacity for optimum performance in the field. In this study, we investigated the effect of long‐term mass rearing on the genetic diversity of A. swirskii. We identified six microsatellite loci from whole‐genome nanopore sequencing of A. swirskii and used these in a comparative analysis of the genetic diversity and differentiation in eight wild populations collected from Israel in 2017 and a commercially available population. Our results indicate that the commercial population is 2.5× less heterozygous than the wild A. swirskii. Furthermore, the commercial population has the highest genetic differentiation from all the natural populations, as indicated by higher pairwise F_st values. Overall, we show that commercially reared A. swirskii have reduced genetic variation compared to their wild counterparts, which may reduce their performance when released to control pests in an integrated pest management (IPM) context.     

Attraction of the predatory mites Typhlodromalus manihoti and Typhlodromalus aripo to cassava plants infested by cassava green mite

The attraction of the predatory mites, Typhlodromalus manihoti and Typhlodromalus aripo, to the host plant-spider mite complex, Manihot esculenta – Mononychellus tanajoa, was investigated with a Y-tube olfactometer. Factors examined included predator starvation period, several combinations of cassava leaf biomass and initial M. tanajoa infestations, M. tanajoa-damaged leaves with mites and/or their residues removed, M. tanajoa alone, and mechanically damaged cassava leaves. We found that females of T. manihoti and T. aripo were significantly attracted to M. tanajoa-infested cassava leaves when the predators were starved for 2, 6, or 10 h. Satiated T. aripo was significantly attracted to infested cassava leaves whereas satiated T. manihoti did not discriminate between infested and non-infested leaves. When a choice was given between either two or four leaves infested with 200 female M. tanajoa and an equivalent number of non-infested leaves, 2 h-starved T. manihoti and T. aripo were significantly attracted to each of the infested groups of cassava leaves. At a density of 12 female M. tanajoa per leaf on four leaves, 2 h-starved T. manihoti was still attracted to M. tanajoa-infested leaves whereas 2 h-starved T. aripo was not attracted. When a choice was given between non-infested cassava leaves and either infested leaves from which only M. tanajoa females had been removed, or infested leaves from which all M. tanajoa and their visible products (web, feces) had been wiped off, T. aripo preferred odors from both types of previously infested leaves. Typhlodromalus manihoti was only attracted to infested leaves from which the M. tanajoa females only had been removed. Finally, the two predators were not attracted to 400 female M. tanajoa on clean cotton wool or to mechanically wounded leaves. This supports the hypothesis that M. tanajoa damage induces volatile cues in cassava leaves that attract T. manihoti and T. aripo to M. tanajoa-infested leaves.     

Screening landraces for additional sources of field resistance to cassava mosaic disease and green mite for integration into the cassava improvement program

Twelve cassava landraces were evaluated for sources of resistance genes to diseases and pests of major economic importance in Africa. The objective was to assess their levels of field resistance to mosaic disease （ACMD）, bacterial blight （CBB）, anthracnose （CAD）, and green mite （CGM）, compared to TMS30572, an elite cultivar widely adopted in Africa. Considerable genotypic variation was observed among cultivars for resistance to ACMD and CGM but not for CBB and CAD. The lowest mean incidence of 12% and severity of 1.8 on a scale of 1-5 for ACMD was recorded for Atu, a landrace with farmer acceptable qualities. In comparison, the improved cultivar, TMS 30572, had a mean disease incidence of 72% and a severity score of 2.8. Another landrace, MS-20 had the lowest CGM damage score （2.1） while TMS 30572 emerged as one of the susceptible cultivars with a damage score of 3. Additional sources of resistance to ACMD and CGM that may possibly be better than the popular improved cultivar, TMS 30572, were identified in this study. These could serve as novel sources of additional genes to complement existing resources for elite cassava breeding in Africa.     

Sampling strategies for assessing the overall density of the cassava green mite (Mononychellus tanajoa)

Six different sampling methods to estimate the density of the cassava green mite, Mononychellus tanajoa, are categorized according to whether leaves or leaflets are used as secondary sampling units and whether the number of leaves on the sampled plants are enumerated, estimated from an independent plant sample, or not censused at all. In the last case, sampling can provide information only on the average number of mites per leaf and its variance, while information on stratum sizes is necessary to estimate the mean number of mites per plant as well. It is shown that leaflet-sampling is as reliable as leaf-sampling for the same number of sampling units. When stratum sizes are estimated from a separate plant sample, sampling time may also be reduced, but the estimated mean density and its variance may be biased if mite density and plant size are correlated. Sampling data show that the within-plant variance contributes relatively little to the overall variance of the population density estimates. It points at a sampling strategy in which the number of primary units (plants) is as large as possible at the expense of secondary units (leaflets) per plant. Mean-variance relationships may be applied to estimate sample variances and can be used even when only one leaflet is taken per plant per stratum. An unequal allocation of primary units among strata can increase precision, but the gain is small compared with an equal allocation. Leaf area can be predicted from the length of the longest leaflet and the number of leaflets.