Assessment of risk of attack to safflower by Ceratapion basicorne (Coleoptera: Apionidae), a prospective biological control agent of Centaurea solstitialis (Asteraceae)

Ceratapion basicorne (Coleoptera: Apionidae) is a prospective biological control agent of yellow starthistle (Centaurea solstitialis, Asteraceae: Cardueae), which is an important invasive alien weed in the western United States. Previous studies have shown that it is possible for this insect to oviposit on and complete development on safflower (Carthamus tinctorius) under no-choice laboratory conditions; however, it has never been reported as a pest of safflower. Field experiments were conducted at three sites in eastern Turkey during 3 years to evaluate the risk of attack on safflower by this insect in its native range. At two sites where C. basicorne was the only apionid observed, no safflower plants were attacked despite high attack rates on yellow starthistle test plants (48–98% of plants infested). At a third site, where C. basicorne and three other species in the same genus; C. scalptum, C. orientale, and C. onopordi were present, 8–26% of safflower plants were infested, but none of the insects reared from safflower during 3 years were C. basicorne. Other authors have reported rearing C. basicorne from field-collected plants of only Ce. solstitialis, Ce. cyanus, Ce. depressa, and Cnicus benedictus. Our results indicate that C. basicorne does not attack safflower under field conditions and that its introduction would not pose a risk to this crop.     

Host plant oviposition preference of Ceratapion basicorne (Coleoptera: Apionidae), a potential biological control agent of yellow starthistle

Ceratapion basicorne is a weevil native to Europe and western Asia that is being evaluated as a prospective classical biological control agent of Centaurea solstitialis (yellow starthistle) in the United States. Choice oviposition experiments were conducted under laboratory conditions to help assess host-plant specificity of the insect. Mean oviposition rates were highest on C. solstitialis (66% of eggs, on a per replicate basis) followed by Centaurea cyanus (bachelor's button 22%), Centaurea melitensis (6%), Centaurea americana (1%), Saussurea americana (3%) and Carthamus tinctorius (safflower 2%). Adult feeding damage followed a similar pattern; however, there was less oviposition relative to the amount of adult feeding on each of the non-target species than on the target host plant, C. solstitialis. Thirteen safflower varieties were tested, and oviposition occurred on eight of them, at low rates. Adult feeding occurred on all safflower varieties tested, although at rates much lower than on yellow starthistle. The results were intermediate between those of previously reported no-choice laboratory and open field experiments. Overall, the combined results support the hypothesis that C. basicorne is not likely to attack any of the non-target plant species tested here except possibly C. cyanus and C. melitensis, which are both invasive alien plants.     

Effect of mechanical damage on emission of volatile organic compounds from plant leaves and implications for evaluation of host plant specificity of prospective biological control agents of weeds

Assessment of host plant specificity is a critical step in the evaluation of classical biological control agents of weeds which is necessary for avoiding possible damage to non-target plants. Volatile organic compounds (VOCs) emitted by plants likely play an important role in determining which plants attract and are accepted by a prospective arthropod agent. However, current methods to evaluate host plant specificity usually rely on empirical choice and no-choice behavioural experiments, with little knowledge about what chemical or physical attributes are stimulating the insect. We conducted experiments to measure the quantitative and qualitative effects on emission of VOCs caused by simple mechanical damage to leaves of plants known to differ in suitability and attractiveness to a prospective agent. More VOCs were detected from damaged than from undamaged leaves for all three species tested. Discriminant analysis was able to correctly distinguish the taxonomic identity of all plants based on their VOC profiles; however, the VOCs that discriminated species among undamaged leaves were completely different from those that discriminated among damaged leaves. Thus, damaged and undamaged plants present different VOC profiles to insects, which should be considered when conducting host plant specificity experiments. An unacceptable non-target plant, Centaurea cineraria, emitted all except one of the VOCs that were emitted by its preferred host plant, Centaurea solstitialis, indicating the importance of compounds that are repellant in host plant specificity. Centaurea cyanus emitted fewer VOCs than C. solstitialis, which suggests that it lacked some VOCs important for host plant recognition.     

Evaluation of the predatory mite <Emphasis Type="Italic">Phytoseiulus macropilis</Emphasis> (Acari: Phytoseiidae) as a biological control agent of the two-spotted spider mite on strawberry plants under greenhouse conditions

The predatory mite Phytoseiulus macropilis is a potential biological control agent of the two-spotted spider mite (TSSM) Tetranychus urticae on strawberry plants. Its ability to control TSSM was recently assessed under laboratory conditions, but its ability to locate and control TSSM under greenhouse conditions has not been tested so far. We evaluated whether P. macropilis is able to control TSSM on strawberry plants and to locate strawberry plants infested with TSSM under greenhouse conditions. Additionally, we tested, in an olfactometer, whether odours play a role in prey-finding by P. macropilis. The predatory mite P. macropilis required about 20 days to achive reduction of the TSSM population on strawberry plants initially infested with 100 TSSM females per plant. TSSM-infested plants attract an average of 27.5 ± 1.0% of the predators recaptured per plant and uninfested plants attracted only 5.8 ± 1.0% per plant. The predatory mites were able to suppress TSSM populations on a single strawberry plant and were able to use odours from TSSM-infested strawberry plants to locate prey in both olfactometer and arena experiments. Hence, it is concluded that P. macropilis can locate and reduce TSSM population on strawberry plants under greenhouse conditions.     

Sub-lethal effects of fenbutatin oxide on prey location by the predatory mite <Emphasis Type="Italic">Iphiseiodes zuluagai</Emphasis> (Acari: Phytoseiidae)

We used a Y-tube olfactometer to assess the sub-lethal effects of the acaricide fenbutatin oxide on the olfactory response of the predatory mite Iphiseiodes zuluagai towards odours from: (1) air or undamaged coffee plants; (2) undamaged or red spider mite Oligonychus ilicis-infested coffee plants; (3) undamaged or false spider mite Brevipalpus phoenicis-infested coffee plants. Predatory mite adult females were exposed to residues of fenbutatin oxide or distilled water on leaf discs during a period of 72 h prior experiments. When exposed to distilled water (control treatments), predatory mites significantly preferred undamaged plants over air, O. ilicis-infested plants over undamaged plants, and they did not prefer B. phoenicis-infested plants over undamaged plants. However, predatory mites that had been exposed to residues of fenbutatin oxide were neither attracted towards undamaged plants nor to O. ilicis-infested plants. Thus, fenbutatin oxide affected negatively the olfactory response of I. zuluagai. We conclude that sub-lethal-effect studies should be considered in pesticide selectivity programs since the ability of predatory mites to locate their prey may be negatively affected by non-lethal concentrations of pesticides.     

From the laboratory to the field: contrasting effects of multi-trophic interactions and agroforestry management on coffee pest densities

Only few factors influencing pest populations can be studied in the laboratory, but many population‐driving factors interact in the field. Therefore, complementary laboratory and field approaches are required for reliable predictions of real‐world patterns and processes. Laboratory and field experiments with the red spider mite, Oligonychus ilicis McGregor (Acari: Tetranychidae), and the coffee leaf miner, Leucoptera coffeella Guérin‐Méneville (Lepidoptera: Lyonetiidae), on coffee plants, Coffea arabica L. (Rubiaceae), were combined to study the relative importance of biotic interactions, including resource preferences and natural‐enemy impact, and habitat factors, such as agroforestry type and management intensity, on coffee pest densities. In the laboratory, leaf discs cut from undamaged coffee plants were significantly preferred by red spider mites over those from plants infested with conspecific mites, leaf rust pathogens [Hemileia vastatrix Berkeley & Broome (Uredinales)], or coffee leaf miners, resulting in higher reproductive success. Similarly, undamaged plants were preferred by coffee leaf miners over red spider mite‐infested plants. However, in the field, red spider mite densities were positively correlated with coffee leaf miner and leaf rust densities, thereby contrasting with laboratory predictions. Hence, our study suggests that the importance of resource preferences and fitness expected based on laboratory experiments was suppressed by environmental conditions in the field, though other unassessed biotic interactions could also have played a role. Furthermore, intensified agroforestry was characterized by higher red spider mite densities, whereas densities of its major natural enemy, the predatory mite Amblyseius herbicolus Chant (Acari: Phytoseiidae), were not related to agroforestry management. Densities of coffee leaf miner and its main natural enemy, a eulophid parasitoid (Hymenoptera), were not affected by management practices. In conclusion, patterns found in the laboratory did not hold for the field, emphasizing the difficulties of extrapolating small‐scale experiments to larger spatial scales and the need to combine both approaches.     

Ectoparasitic mites and their Drosophila hosts

Only two parasite interactions are known for Drosophila to date: Allantonematid nematodes associated with mycophagous Drosophilids and the ectoparasitic mite Macrocheles subbadius with the Sonoran Desert endemic Drosophila nigrospiracula. Unlike the nematode-Drosophila association, breadth of mite parasitism on Drosophila species is unknown. As M. subbadius is a generalist, parasitism of additional Drosophilids is expected. We determined the extent and distribution of mite parasitism in nature Drosophilids collected in Mexico and southern California. Thirteen additional species of Drosophilids were infested. Interestingly, 10 belong to the repleta species group of the subgenus Drosophila, despite the fact that the majority of flies collected were of the subgenus Sophophora. In all cases but 2, the associated mites were M. subbadius. Drosophila hexastigma was found to have not only M. subbadius, but another Mesostigmatid mite, Paragarmania bakeri, as well. One D. hydei was also found to have a mite from genus Lasioseius attached. In both choice and no-choice experiments, mites were more attracted to repleta group species than to Sophophoran. The extent of mite parasitism clearly is much broader than previously reported and suggests a host bias mediated either by mite preference and/or some mechanism of resistance in particular Drosophilid lineages.     

Phoretic Poecilochirus mites specialize on their burying beetle hosts

Recurring species interactions can cause species to adapt to each other. Specialization will increase the fitness of symbionts in the coevolved association but may reduce the flexibility of symbiont choice as it will often decrease fitness in interactions with other than the main symbiont species. We analyzed the fitness interactions between a complex of two cryptic mite species and their sympatric burying beetle hosts in a European population. Poecilochirus mites (Mesostigmata, Parasitidae) are phoretic on burying beetles and reproduce alongside beetles, while these care for their offspring at vertebrate carcasses. While Poecilochirus carabi is typically found on Nicrophorus vespilloides beetles, P. necrophori is associated with N. vespillo. It has long been known that the mites discriminate between the two beetle species, but the fitness consequences of this choice remained unknown. We experimentally associated both mite species with both beetle species and found that mite fitness suffered when mites reproduced alongside a nonpreferred host. In turn, there is evidence that one of the beetle species is better able to cope with the mite species they are typically associated with. The overall fitness effect of mites on beetles was negative in our laboratory experiments. The Poecilochirus mites studied here are thus specialized competitors or parasites of burying beetles.     

Interactions between white mealybugs and red spider mites sequentially colonizing coffee plants

Plants under herbivore attack often respond defensively by mounting chemical and physical defences. However, some herbivores can manipulate plant defences to their own benefit by suppressing the expression of induced defences. These herbivore‐induced changes specific to the attacking herbivore can either facilitate or impede the colonization and establishment of a second herbivore. Although recent studies have focused on the effect of multiple herbivory on plant induced response and the third trophic level, few have examined the ecological relevance of multiple herbivores sharing the host. Here, we investigated whether herbivory by the white mealybug Planococcus minor (Maskell) (Hemiptera: Pseudococcidae) or the red spider mite Olygonychus ilicis (McGregor) (Acari: Tetranychidae), two herbivores that peak in coffee plantations during the dry season, may facilitate the colonization and establishment of the other species in coffee plants. Dual‐choice arena tests showed that white mealybugs preferred mite‐infested over uninfested coffee plants as hosts. Fifteen days after the release of 50 first‐instar P. minor nymphs, greater numbers of nymphs and adults were found on mite‐infested than uninfested plants, indicating superior performance on mite‐infested plants. On the other hand, female red spider mites did not show clear preference between uninfested and mealybug‐infested plants and deposited similar numbers of eggs on both treatments. In a no‐choice test, red spider mites performed poorly on mealybug‐infested plants with a smaller number of eggs, nymphs, females and males found in mealybug‐infested plants relative to uninfested plants. Thus, our results indicate that coffee plants are more likely to be infested by the red spider mite before white mealybug, rather than the inverse sequence (i.e. mealybug infestation followed by red spider mites). Our findings are discussed in the context of plant manipulation reported for pseudococcid mealybugs and spider mites.     

Plants,mites and mutualism: leaf domatia and the abundance and reproduction of mites on Viburnum tinus (Caprifoliaceae)

Associations between mites and leaf domatia have been widely reported, but little is known about their consequences for either plants or mites. By excising domatia from leaves of the laureltinus, Viburnum tinus L. (Caprifoliaceae), in the garden and laboratory, we showed that domatia alter the abundance, distribution, and reproduction of potential plant mutualists. Over 4 months, leaves with domatia on six garden shrubs had 2–36 times more predatory and microbivorous mites, and more mite eggs than leaves without domatia. However, this effect varied among plants and was weaker on one shrub with few mites on its leaves. Domatia also influenced the distribution of mites on leaves. A significantly higher fraction of mites, representing all life stages, was found in vein axils of leaves with domatia than in vein axils on leaves without domatia. Single-leaf experiments in the laboratory showed that domatia enhanced reproduction by the predatory mite, Metaseiulus occidentalis, especially at low relative humidity (30–38%). When domatia were removed, oviposition was reduced significantly only at low relative humidity, suggesting that domatia provide mites with refuge from environmental extremes on the leaf surface. Moreover, the use of domatia by predatory mites may reduce the impact of some plant enemies. In two experiments where prey consumption was measured, M. occidentalis ate significantly higher percentages of the eggs of the two-spotted spider mite (Tetranychus urticae). Our results are consistent with the viewpoint that mite-domatia associations are mutualistic. By directly aiding and abetting the third trophic level, plants with leaf domatia may increase the efficiency of some predaceous and microbivorous mites in consuming plant enemies.     

Biological control of broad mites (<Emphasis Type="Italic">Polyphagotarsonemus latus</Emphasis>) with the generalist predator <Emphasis Type="Italic">Amblyseius swirskii</Emphasis>

The broad mite is a serious pest of a variety of crops worldwide. Several phytoseiid mites have been described to control these mites. However, broad mites are still one of the major pest problems on greenhouse pepper in South-eastern Spain. The generalist predatory mite A. swirskii is widely used against other pests of pepper plants such as thrips and whiteflies, the latter being a vector of broad mites. We assessed the potential of A. swirskii to control broad mites. The oviposition rate of A. swirskii on a diet of broad mites was lower than on a diet of pollen, but higher than oviposition in the absence of food. Population-dynamical experiments with A. swirskii on single sweet pepper plants in a greenhouse compartment showed successful control of broad mites.     

Interactions in a tritrophic acarine predator-prey metapopulation system III: effects of Tetranychus urticae (Acari: Tetranychidae) on host plant condition

Spider mites are serious pests on many economically important plant species, because they may reduce plant productivity and, at high mite densities, overexploit and even kill the host plants. We have conducted a series of greenhouse experiments to quantify the effects of two-spotted spider mites (Tetranychus urticae) on host plants (Phaseolusvulgaris). The average amount of chlorophyll per cm² leaf area was used as a measure of plant condition. It was shown that chlorophyll concentration decreases with plant age and intensity of spider mite feeding. Damage caused by spider mites was assessed visually, using the Leaf Damage Index (LDI) defined by, and a mathematical relationship between the visual measurements and the amount of chlorophyll/cm² was fitted to data. The relationship may serve as a short-cut to estimate overall plant injury, expressed as the relative loss of chlorophyll/cm² leaf area caused by spider mites (D). D takes values between 0 (no injury) and 1 (all leaves dead). A highly significant positive relationship between the instantaneous spider mite density and D was found, even though D is expected to reflect the cumulated density of mites (mite-days). A model of plant growth incorporating information about plant age and D predicts that plant area has a maximum when plant age is about 60 days, and that plant area decreases exponentially with an increase in D. This revised version was published online in July 2006 with corrections to the Cover Date.     

Altered host plant preference of Tetranychus urticae and prey preference of its predator Phytoseiulus persimilis (Acari: Tetranychidae, Phytoseiidae) on transgenic Cry3Bb-eggplants

The behavior of the two-spotted spider mite, Tetranychus urticae Koch and the predatory mite Phytoseiulus persimilis A.-H. was investigated in laboratory experiments with transgenic Bt-eggplants, Solanum melongena L., producing the Cry3Bb toxin and corresponding isogenic, non-transformed eggplants. In bitrophic experiments, dual-choice disc tests were conducted to reveal the effects of transgenic eggplants on host plant preference of T. urticae. Adult spider mite females were individually placed on leaf discs (2 cm diameter) and were observed during five days. Females occurred significantly more frequently on transgenic halves on which also significantly more T. urticae eggs were found. The effects of a Cry3Bb-eggplant fed prey on the feeding preference of P. persimilis were investigated in tritrophic experiments. Sixteen spider mite females, eight of which had been taken from transgenic and eight from isogenic eggplants, were offered to well-fed females of P. persimilis and numbers of respective spider mites consumed were registered 12 h later when the predators were offered new spider mites again. This procedure was repeated six times. The results revealed that predatory mites consumed significantly less Bt-fed spider mites than prey that had been raised on control eggplants. These results indicate that eggplants expressing the Cry3Bb toxin for resistance against the Colorado potato beetle are more preferred by spider mites but are less preferred by their predator P. persimilis. Possible consequences of these findings for biological control of spider mites on eggplants are discussed.     

Short-term response of arbuscular mycorrhizal association to spider mite herbivory

We examined effects of aboveground herbivory by spider mites (Tetranychus urticae) on colonization and activity of arbuscular mycorrhizal fungi (AMF; Gigaspora margarita) using potted plants (Lotus japonicus). We evaluated changes in arbuscular mycorrhizal (AM) association two ways: (1) conventional trypan blue staining of mycorrhizal hyphae to examine AMF biomass in roots (mycorrhizal colonization) and (2) vital staining for a mycorrhizal enzyme (succinate dehydrogenase, SDH) to examine mycorrhizal activity (SDH activity). Mycorrhizal colonization and SDH activity started to increase 4 days after aboveground herbivory, and returned to the initial levels in the absence of mite herbivory in 7 and 12 days, respectively. These results suggest that the change in AM association in response to mite herbivory is a short-term response.     

Invasive species grows faster,competes better,and shows greater evolution toward increased seed size and growth than exotic non-invasive congeners

Comparisons of introduced exotics that invade and those that do not can yield important insights into the ecology of invasions. Centaurea solstitialis, C. calcitrapa, and C. sulphurea are closely related, share a similar life history and were each introduced to western North America from Southern Europe ~100–200 years ago. However, of these three species, only C. solstitialis has become invasive. We collected seeds from different populations for each of the three species both in the native range of Spain and the non-native range of California, measured individual seed mass, and grew plants from these seeds in a greenhouse experiment in Montana. The invasive C. solstitialis had the smallest seeds and seedlings of the three congeners. However, in contrast to its non-invasive congeners, C. solstitialis had the highest relative growth rates when grown in competition. C. solstitialis was also the only species to show significant differences in traits between populations from different ranges, with plants from the non-native range of California demonstrating greater competitive resistance, larger seed size, and larger seedling mass than plants from the native range in Spain. This suggests that C. solstitialis may be evolving toward larger seed and seedling sizes in this non-native range. Relative growth rate showed no inter-regional variation for any species, but was higher for C. solstitialis than its congeners when in competition, and thus may interact with the evolution of larger seeds and plant mass in ways that contribute to the extraordinary invasive success of this species.     

Does a vascular fungus of tomato induce a defence response or a change in host plant quality that also affects the oviposition of spider mites?

It has been suggested that previous infection by a vascular fungus causes induced resistance against two-spotted spider mites. To test the generality of this phenomenon, a series of experiments was carried out using two lines of tomato, differing only in resistance againstFusarium. In addition, tests were done in order to see whether the defense response against the fungus also affects the phytophagous mite directly. Inoculation of tomato plants with a vascular fungus (Fusarium oxysporum f.sp.lycopersici race 1) prior to infestation with spider mites caused a decrease in the rate of oviposition of two-spotted spider mites (Tetranychus urticae) on aFusarium-susceptible line, but only when plants were moderately to severely wilted. Spider mite oviposition did not change significantly of a previously inoculatedFusarium-resistant line.AsFusarium causes vascular occlusion and wilting of the plants, drought stress was experimentally induced to determine its influence on the reduction of oviposition. Drought caused a significant reduction in spider mite oviposition. We conclude that the effect of previousFusarium-inoculation on spider mite oviposition is primarily due to the fungus affecting the quality of the host plant (including the effect it may have on the composition of defensive compounds), rather than due to the stimulation of the defense system of the plant. SinceFusarium seals off the xylem vessels, thereby causing wilting of susceptible plants, the reduction in mite oviposition may well be due to drought stress in the leaves, rather than due to the production of phytoalexins.     

Development of biological methods for the control of Tetranychus urticae on tomatoes using Phytoseiulus persimilis

The biological control of red spider mite using the predatory mite Phytoseiulus persimilis was investigated in 1971, 1972 and 1974. Experiments in small glasshouse compartments showed that the predator should be introduced when the leaf damage index is < 0–3. Uniform and/or patch introductions of P. persimilis at different rates were made into naturally occurring red spider mite infestations on commercial nurseries. In eleven of the seventeen experiments good control was achieved. Introduction of the predator soon after damage appeared on the crop was essential. Poor control was obtained when the predator failed to establish itself, where very large numbers of diapausing mites emerged and built up rapidly or where the predator, introduced into patches, failed to colonize infested plants elsewhere in the crop. When spider mites and predators were introduced on to one-fifth or one-tenth of the plants in a propagating house, a satisfactory interaction was maintained for 4–6 wk after planting out. The predators then died unless red spider mites emerged from diapause or were introduced. Petroleum oil sprays were sometimes used successfully in the presence of the predator to reduce high red spider mite infestations and re-establish the biological equilibrium.     

Pest species diversity enhances control of spider mites and whiteflies by a generalist phytoseiid predator

To test the hypothesis that pest species diversity enhances biological pest control with generalist predators, we studied the dynamics of three major pest species on greenhouse cucumber: Western flower thrips, Frankliniella occidentalis (Pergande), greenhouse whitefly, Trialeurodes vaporariorum (Westwood), and two-spotted spider mites, Tetranychus urticae Koch in combination with the predator species Amblyseius swirskii Athias-Henriot. When spider mites infested plants prior to predator release, predatory mites were not capable of controlling spider mite populations in the absence of other pest species. A laboratory experiment showed that predators were hindered by the webbing of spider mites. In a greenhouse experiment, spider mite leaf damage was lower in the presence of thrips and predators than in the presence of whiteflies and predators, but damage was lowest in the presence of thrips, whiteflies and predators. Whitefly control was also improved in the presence of thrips. The lower levels of spider mite leaf damage probably resulted from (1) a strong numerical response of the predator (up to 50 times higher densities) when a second and third pest species were present in addition to spider mites, and (2) from A. swirskii attacking mobile spider mite stages outside or near the edges of the spider mite webbing. Interactions of spider mites with thrips and whiteflies might also result in suppression of spider mites. However, when predators were released prior to spider mite infestations in the absence of other pest species, but with pollen as food for the predators, we found increased suppression of spider mites with increased numbers of predators released, confirming the role of predators in spider mite control. Thus, our study provides evidence that diversity of pest species can enhance biological control through increased predator densities.     

Field assessment of host plant specificity and potential effectiveness of a prospective biological control agent, Aceria salsolae, of Russian thistle, Salsola tragus

The eriophyid mite, Aceria salsolae de Lillo and Sobhian, is being evaluated as a prospective classical biological control agent of invasive alien tumbleweeds, including Salsola tragus, S. collina, S. paulsenii and S. australis, in North America. Previous laboratory experiments to determine the host specificity of the mite indicated that it could sometimes persist and multiply on some nontarget plants, including Bassia hyssopifolia and B. scoparia. These are both European plants whose geographic range overlaps that of the mite, but the mite has never been observed on them in the field. A field experiment was conducted in Italy to determine if the mite would infest and damage these plants under natural outdoor conditions. The results indicate that this mite does not attain significant populations on these nontarget plants nor does it significantly damage them. Salsola tragus was heavily infested by A. salsolae, and plant size was negatively correlated to the level of infestation. Although S. kali plants were also infested, their size did not appear to be affected by the mites. The other nontarget plants were not as suitable for the mite in the field as in previous laboratory experiments. We conclude that there would be no significant risk to nontarget plants as a result of using A. salsolae as a biological agent to control Salsola species in North America.     

Control of the broad mite (Polyphagotarsonemus latus (Banks)) on organic greenhouse sweet peppers (Capsicum annuum L.) with the predatory mite, Neoseiulus cucumeris (Oudemans)

The predatory mite Neoseiulus cucumeris (Oudemans) (Acarina: Phytoseiidae) successfully controlled the broad mite Polyphagotarsonemus latus (Banks) (Acarina: Tarsonemidae) on two varieties of greenhouse-grown sweet peppers (Capsicum annuum L.). A survey of pre-plant seedlings showed that nurseries were a source of infestation for the broad mite. The predatory mites were released twice (on day 1 and 5, or 15 days later) on each plant, every second plant or every fourth plant. Broad mite populations were evaluated by sampling young leaves from the top of the plant. The effect of the broad mite on plant height, dry mass and yield was evaluated. Additionally, since N. cucumeris is known to control thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), blue sticky traps and flower sampling were used to evaluate changes in thrips populations. All three release rates of N. cucumeris significantly (P<0.05) controlled broad mite populations, but when the predatory mites were released only on every fourth plant, the overall height and yield of the plants were adversely affected by broad mites. Releasing N. cucumeris on each or every second plant was as efficacious in controlling broad mites as sulfur treatments in terms of plant height, dry mass and yield. Plants treated with sulfur, however, had significantly higher thrips populations and fruit damage.