THE PATTERN OF FIELD INFECTION OF POTATO BY THE BEET RINGSPOT STRAIN OF TOMATO BLACK-RING, A SOIL-BORNE VIRUS

The potential importance of the beet ringspot strain of tomato black-ring, a soil-borne virus, was assessed by growing stocks of Kerr's Pink potato for 1 year on infested land and subsequently on uninfested land. The incidence of infection in two stocks was 39 and 8% in the first year on uninfested land, and 29 and 5% after 2 years.
The virus was usually restricted to the roots of plants in the first year of infection, but a few plants showed black rings and spots in their leaves. In the second year, 20–55% of the plants grown from tubers set by symptomless, but infected, mother plants were infected: many of these showed leaf necrosis, others had stunted shoots, and cupped and distorted leaves; some were symptomless although systemically infected. In the third and fourth years, most of the progeny from plants which had symptoms or which were symptomless but systemically infected, contained the virus: nearly all such infected plants were stunted and distorted or were symptomless. Infection decreased the weight of tubers produced by plants with severe necrotic spotting but not the yield of plants with less necrosis. The number and weight of tubers per plant were decreased by 15 and 20% respectively, in symptomless systemically infected plants, and by 20 and 30% in stunted plants.     

Effect of feeding by larvae of Inopus rubriceps (Diptera: Stratiomyidae) on development and growth of sugarcane.

Pot experiments were used to investigate the effect of root-feeding larvae of the soldier fly Inopus rubriceps (Macquart) on shoot production from sugarcane planting pieces (setts) and on growth and ratooning of sugarcane plants. Shoot elongation was inhibited while setts were exposed to larvae, and it resumed when larvae were removed. Infested setts produced a greater weight of roots than uninfested setts. Similar symptoms were induced by mechanical root pruning, suggesting that the effect of soldier fly larvae on setts may be a redirection of growth from the shoot to roots due to root damage. Larvae had a greater effect on shoot production at lower temperature, particularly in cultivar 'Q151', which had a higher temperature threshold than 'CP44-101'. Temperature and cultivar may influence the harmful effect of soldier fly larvae on sett germination by changing the differential rates of plant growth and larval feeding. When growing plants were exposed to larvae, the infested plants were slightly smaller at harvest and subsequently produced many fewer ratoon shoots from underground buds than uninfested plants. Shoot elongation from buds was also inhibited in setts cut from the above-ground stalks of infested plants. Analysis of nutrient levels in plants did not indicate the mechanism for ratooning inhibition, because levels of time 10 elements analyzed were at least as high or higher in infested plants. Infestation was associated with an increased level of sucrose and a reduced level of fructose in stalks. The inhibitory effect of larval feeding on ratooning was not reversed when larvae were removed from pots 10 wk before harvest. However, new stubble produced from infested plants then ratooned normally after a second harvest, provided the new roots were not attacked. The symptoms of larval feeding in growing plants are unexplained, but may be caused by the prolonged withdrawal of sap from roots or the injection of some inhibitory substance by larvae.     

Physiological studies of a hybrid between populations of Dactylis glomerata from contrasting climatic regions. II. Intra population variation

Mushroom compost was treated with nematicides and infested with Aphelenchoides composticola at the time of filling into growing containers. Yields of mushrooms from infested untreated control composts were reduced to 40–60% of yields from uninfested control compost. Yields from infested compost treated with fenamiphos emulsifiable concentrate (e.c.) at 10 or 20 mg a.i./kg, thiabendazole wettable powder at 40 or 60 mg a.i./kg or oxamyl granules at 20 mg a.i./kg were as high as from uninfested controls. Compost treated with granules of AC 64,475 up to 20 mg a.i./kg or ethoprophos or thionazin up to 80 mg a.i./kg gave yields significantly lower than uninfested controls. Numbers of nematodes rose to about 10⁶/20 g of compost in untreated compost and then fell, and a similar peak occurred in treatments in which yields were substantially reduced by nematode damage. Treatments which yielded as well as the uninfested controls held maximum nematode numbers down to about 10V20 g of compost but populations stayed at this level or tended to rise while numbers in untreated compost fell. Incorporation of fenamiphos in casing or its application to the surface of beds 3 wk after cropping began gave lower yields than the uninfested control but mushrooms were being produced late in the cropping cycle. Fenamiphos e.c. at 20 mg ai./kg incorporated in compost is considered a practical preventive measure for control of A. composticola.     

Effects of Russian wheat aphid infestation on barley plant response to drought stress

The influence of Russian wheat aphid ( Diuraphis noxia Mordvilko) infestation on the response of barley ( Hordeum vulgare L. ev Hazen) plants to drought stress was investigated. Fourteen-day-old plants were infested with eight apterous adult aphids, which were removed 7 days later with systemic insecticide. Leaves previously infested with aphids had lower relative water content, reduced stomatal conductance, more negative water potential, lower levels of chlorophyll and higher levels of amino-N, proline and glycinebetaine than corresponding leaves from uninfested plants. When water was withheld for a period of 7 days after aphids were removed, the relative water content of previously infested plants dropped steadily from 0.89 to 0.60, while the relative water content of uninfested plants remained at about 0.94 for the first 4 days of the drought stress period followed by a steady drop to about 0.77 by the end of the drought stress period. Leaf water potentials dropped steadily during the drought stress period in both previously infested (-1.14 to -1.91 MPa) and unin-fested (-0.54 to -1.52 MPa) plants. Analysis of glycinebetaine and proline levels at the end of the drought stress period indicated that leaves of previously infested plants accumulated lower levels of these solutes than leaves from uninfested plants. Upon alleviation of drought stress, plants previously infested with aphids showed little increase in dry weight while younger leaves and tillers from uninfested plants showed large increases. It is concluded that Russian wheat aphids cause drought-stress symptoms in leaves of infested plants even in the presence of ample root moisture. The observations of low levels of glycinebetaine and proline present in leaves after water was withheld from roots and lack of leaf growth upon alleviation of drought stress in previously-infested plants, suggest that aphid infestation limits the capacity of barley plants to adjust successfully to drought stress.     

Tomato Growth in Soil Amended with Sugar Mill By-Products Compost

Sugar mill by-products compost may be a good soil amendment to promote tomato (Lycopersicon esculentum L.) growth. In addition, the compost may further promote plant growth by inoculation with N₂-fixing bacteria. Compost from sugar-mill waste was prepared with and without the N₂-fixing bacteria, Azotobacter vinelandii, Beijerinckia derxii and Azospirillum sp. and incubated for 50 days. Each compost type was added to 10 kg of soil in pots at rates of 0, 15, and 45 g with and without fertilizer N at rates of 0, 0.75, and 1.54 g. A blanket application of P and K was applied to all pots. Shoot and root dry weights and N content of the whole plant was measured at 55 days. Dry weight of tomato shoots was increased by 40% by addition of fertilizer N and root weight was increased by 66%. Without fertilizer N the high rate of inoculated compost increased shoot growth 180% and uninoculated compost increased shoot growth 112%. For most treatments with and without fertilizer N, inoculated compost enhanced shoot growth and nitrogen content more than uninoculated compost. Root weights were nearly doubled by addition of either compost in comparison to the 0 N treatment. At the low rate of compost addition without fertilizer N, root weight was the same for uninoculated and inoculated compost but at the high rate of compost addition root weight was 32% higher for inoculated compost. The N₂-fixing bacteria colonized roots when inoculated compost was used. Sugar mill by-products compost proved to be an effective soil amendment for promoting the growth of tomato plants.     

Role of volatile infochemicals in foraging behavior of the leafminer parasitoidDacnusa sibirica (Diptera: Agromyzidae)

Previous investigations suggested that the leafminer parasitoid Dacnusa sibirica Telenga does not use a volatile hostrelated infochemical in foraging for hosts. Parasitoids landed with equal frequencies on an uninfested tomato plant and on a tomato plant infested with larvae of the leafminer Liriomyza bryoniae (Kalt.) (Hendrikse et al., 1980). In contrast, we found that volatile infochemicals emitted by uninfested and leafminer-infested tomato plants differently affected the parasitoid 's foraging behavior in a windtunnel. This was obvious from the proportion of wasps flying upwind but not from the proportion of wasps landing on the leaves. Latency time on an uninfested tomato leaflet and proportion of latency time devoted to preflight antennal behavior were influenced by the presence of upwind infested or uninfested tomato leaves. However, these parameters were not affected by odors in the absence of visual plant stimuli. Our data provide a new view on foraging behavior of Dacnusa sibirica.     

Pre- and post-landing response of the parasitoid Encarsia formosa to whitefly hosts on Gerbera jamesonii

One of the factors that may complicate biological control of the greenhouse whitefly on Gerbera jamesonii by Encarsia formosa is the rosette shape of this ornamental, which differs from the vertical shape of most vegetable plants (cucumber, egg plant, tomato, etc.). Therefore, host-habitat location and the behaviour prior to landing on uninfested and infested leaves was studied. Attraction of E. formosa from a short distance by infested leaves could not be detected: the parasitoid females landed at random on uninfested and infested leaves. After the first landing, a redistribution of the wasps occurred on the leaves. After 24 h three times as many wasps were found on the infested leaves than on uninfested ones. In a dispersal experiment with four plants, E. formosa appeared to have no preference for landing on leaves of the medium age class, which is the age class on which most of the whiteflies in a suitable stage for parasitism occur. Twenty percent of the parasitoids were found on the plants 20 min after releasing them. These results were independent of the plant cultivar and the host density on the plants. In the course of 8 h, the number of E. formosa females recovered from plants increased linearly, and this increase was greater on plants where hosts were present and also greater on the plant cultivar with the lowest trichome density. After 24 h, the percentage of females was highest (56%) on plants with the highest host density. E. formosa females were arrested on leaves where hosts were present. Contrary to our expectation, the results from the two G. jamesonii cultivars that differed strongly in leaf hairiness were not significantly different in most experiments. Only at the high host density was parasitism found to be lower on the cultivar with the higher hair density. Parasitoids may walk on top of the `hair coverlet' of cultivars with high trichome density and, therefore, be hampered less than expected.     

Nectar and honeydew feeding of Phlebotomus papatasi in a focus of Leishmania major in Neot Hakikar oasis.

Feeding of Phlebotomus papatasi Scopoli on nectar and honeydew was investigated in Neot Hakikar, an oasis in the southern Jordan Valley. Sand flies were caught with miniature light traps in cleared areas with large Tamarix nilotica Bunge bushes, in colonies of the sandrat Psammomys obesus Cretzschmar. Fly series were trapped and compared according to the condition of T. nilotica bushes: with flowers, soiled with honeydew excreted by cicadas, or without flowers. Near flowering bushes the catch was five times greater (7.9: 1.6 flies/trap) and the proportion of sugar-positive flies was also much greater (49.9:17.3%) than near bushes without flowers. The catch was three times greater (6.6:2.2 flies/trap) near cicada- infested than near uninfested bushes. Color markers within the gut, obtained from infested or uninfested bushes that had been sprayed with food dye, indicated feeding of 33.2% and 4.5% of these series, respectively. Sand flies were strongly attracted to flowers of T. nilotica. In similar trap series, those baited with flowering branches caught 231 flies, whereas with baits of honeydew- soiled branches, control regular branches or wet filter paper, the catch ranged between 11 to 15 flies. This study is the first evidence of nectar feeding by sand flies in the field and it indicates that nectar may be an important and an attractive source of sugar.     

Phytophthora cryptogea root rot of tomato in rockwool nutrient culture:

The effect of root temperature on growth and yield of rockwool-grown tomato plants infected with Phytophthora cryptogea was investigated. Measurements of shoot and root growth were taken at high (25^oC) and low (15^oC) root temperatures during the generative phase of growth. The growth of roots of healthy and P. cryptogea-infected tomato plants in rockwool blocks was higher in plants grown with roots at 25^oC than at 15^oC after 60 days and a similar effect was found in slabs after 98 days. Under sub-optimal conditions for growth the disease became severe when root temperatures were low. Growth of roots was greatest when roots were maintained at a high temperature in combination with an ambient air temperature of c. 15^oC and the response was greater in cv. Counter than cvs Calypso and Marathon. Water-soluble carbohydrates of roots were higher in those produced in blocks than slabs and were reduced by infection compared to healthy plants with roots at 15^oC and 25^oC. Reduced transpiration rates were found 17 days after inoculation in symptomless plants grown at a root temperature of 25^oC. Infection, regardless of the temperature of the roots or cultivar, led to reduced stem growth. The plants grown at 25^oC were taller than those with a root temperature of 15^oC. After 9 wk of harvest, the cumulative fruit yields in infected cvs Counter and Calypso grown at 25^oC were comparable to that in healthy plants grown at either temperature and cumulative fruit numbers followed a similar pattern. High root temperatures led to delayed fruit ripening between weeks 3–10 and a larger number of unripe fruit. The weight of unripe fruit from infected plants grown at 25^oC at the terminal harvest was higher than from healthy plants with roots maintained at 15^oC.     

Evaluation of Dry Ice as a Potential Cryonematicide for Meloidogyne incognita in Soil

Solid CO₂ (dry ice) was added to pots containing soil that was infested either with eggs of the root-knot nematode, Meloidogyne incognita, or with tomato (Lycopersicon esculentum ''Rutgers'') root fragments that were infected with various stages of the nematode. Two hours after dry ice was added, thermocouples in the soil recorded temperatures ranging from -15 °C to -59 °C. One day after treatment with the dry ice, the temperature of the soil was allowed to equilibrate with that of the greenhouse, and susceptible tomato seedlings were planted in pots containing infested soil treated or untreated (controls) with dry ice. After 5 weeks, roots were removed from the pots and nematode eggs were extracted and counted. Plants grown in soil infested with eggs and receiving dry ice treatment had less than 1% of the eggs found in the controls; plants from soil infested with root fragments and receiving dry ice treatment had less than 4% of the eggs found in controls. Dry ice used to lower soil temperature may have potential as a cryonematicide.     

Inhibition of seed germination and development of tomato plants in soil infested with Pseudomonas tomato

Infestation of sterilised or natural soil with Pseudomonas tomato at inoculum concentrations of 10² to 10⁹ propagules/ml inhibited germination of seeds and caused damping-off of tomato cv. VF-198, susceptible to bacterial speck. Infestation with saprophytic P. fluorescens at an inoculum concentration of 10⁹ propagules/ml did not cause any damage. Germination of seeds of tomato cv. Rehovot-13, resistant to P. tomato, was not affected in P. tomato-infested natural soil, but was inhibited when tested in P. tomato-infested, sterilised soil. Tomato plants which were symptomless from sowing to the flowering stage when growing in infested soil had 20–30% less foliage than plants growing in uninfested soil.     

Tecia solanivora infestation increases tuber starch accumulation in Pastusa Suprema potatoes

In response to infestation with larvae of the Guatemalan tuber moth(Tecia solanivora), some Solanum tuberosum(potato) varieties exhibit an overcompensation response, whereby the total dry mass of uninfested tubers is increased. Here, we describe early responses,within the first few days, of T. solanivora feeding, in the Colombian potato variety Pastusa Suprema. Nontargeted metabolite profiling showed significant secondary metabolism changes in T. solanivora-infested tubers,but not in uninfested systemic tubers. In contrast,changes in primary metabolism were greater in uninfested systemic tubers than in the infested tubers, with a notable 80% decline in systemic tuber sucrose levels within 1 d of T. solanivora infestation. This suggested either decreased sucrose transport from the leaves orincreased sink strength, i.e., more rapid sucrose to starch conversion in the tubers. Increased sucrose synthesis was indicated by higher rubisco activase and lower starch synthase gene expression in the leaves of infested plants.Elevated sink strength was demonstrated by 45% more total starch deposition in systemic tubers of T. solanivorainfested plants compared to uninfested control plants.Thus, rather than investing in increased defense of uninfested tubers, Pastusa Suprema promotes deposition of photoassimilates in the form of starch as a response to T. solanivora infestation.     

The effect of the cassava green mite Mononychellus tanajoa on the growth and yield of cassava Manihot esculenta in a seasonally dry area in Kenya

The effect of the cassava green mite Mononychellus tanajoa on the growth and yield of cassava Manihot esculenta was studied over a 10-month period in two field trials near Lake Victoria in Kenya. One plot was maintained free of mites by means of acaricide, while the other was artificially infested.The highest population density of M. tanajoa occurred during the dry season. A maximum leaf area index (LAI) of about 2 was reached at the onset of the dry season. The total leaf area of mite infested plants was reduced compared with uninfested plants during the dry spell. During the following rainy season infested plants recovered and attained the same leaf area as uninfested plants. A multiple regression model predicting the leaf area showed that 58% of the seasonal variation could be explained by plant age, soil water, and leaf injury.The net growth rate of infested plants was lower than that of uninfested plants. Maximum values of 21 (infested plants) and 49 (uninfested plants) g m^-2 week^-1 were attained at the onset of the second rainy season. No difference was found between uninfested and infested plants with respect to net assimilation rates per unit leaf area during the dry season. The net assimilation rates reached a maximum almost at the same time as the growth rates, but the infested plants peaked slightly earlier and at a lower level than the uninfested plants. M. tanajoa did not affect the relative allocation of dry matter into stems and storage roots, but the absolute allocation of dry matter declined with increasing mite injury. Thus, after 10 months the dry matter of infested plants was reduced by 29% and 21% for storage roots and stems, respectively, compared with the uninfested plants.     

The effect of host quality and crowding on the settling and take-off of cereal aphids

Settling and take-off behaviour of Sitobion avenae was studied in the laboratory using infested and uninfested wheat at a range of developmental stages. Of the later developmental stages of wheat alate S. avenae preferred to settle on and gave birth to relatively more offspring on flowering and watery-ripe plants. The time to take-off of alatae which matured on wheat was influenced by both the developmental stage of their host plant and the degree of crowding they experienced. All alatae flew but those isolated on flowering plants stayed longer than those crowded or isolated on any of the other developmental stages tested. Similarly the number of offspring produced before take-off was inversely related to the degree of crowding and positively to the time spent on a plant before take-off.     

Effects of Pyrenochaeta lycopersici infection on nutrient uptake by tomato plants

The growth of young tomato plants in nutrient solution or in soil and infected with Pyrenochaeta lycopersici Schneider & Gerlach, the cause of tomato brown root rot, was decreased relative to that of uninfected plants. The roots of plants grown in nutrient solution and infected with a mycelial mat of the pathogen contained lower concentrations of potassium and higher concentrations of calcium than roots of uninfected plants. These changes occurred largely in the visibly affected tissue, as opposed to the root system as a whole. The concentrations of magnesium, total nitrogen and phosphorus in the roots of infected plants were not significantly different from those of control plants. Magnesium, nitrogen and phosphorus concentrations in the tops of infected plants were also not significantly different from those of healthy plants, but no consistent changes were found in the concentrations of calcium and potassium. Young tomato plants grown in soil infested with P. lycopersici contained lower concentrations of phosphorus and potassium in the tops than plants grown in sterilized soil. It was not possible to separate intact damaged root systems of infected plants from soil. The changes in composition found in infected plants are discussed in relation to possible methods of manipulating the nutrition of the plant to offset the effects of the disease on crop yield.     

Use of composts to manage corky root disease in organic tomato production

Corky root disease of tomato caused by Pyrenochaeta lycopersici is an economically important disease in organic tomato production. This study aimed to evaluate the effects of various composts consisting of green manure, garden waste and horse manure against corky root disease through bioassay under greenhouse conditions, where soil naturally infested with P. lycopersici was used as a root substrate. The various composts were mixed at a rate of 20% (v/v) with the infested soil. Disease severity (measured as infected roots) in the unamended soil was compared with that in the soil–compost mixtures. One of the composts made from garden waste significantly reduced the disease, whereas horse manure compost significantly stimulated it. Lower concentrations of NH₄‐N and total carbon and a higher concentration of Ca in the substrate were correlated with lower level of corky root disease. Addition of green manure or garden waste compost to the infested soil increased total microbial activity or population density of copiotrophic bacteria and actinomycetes, respectively. However, increased microbial activity or microbial population in soil–compost mixtures was not associated with a reduction in corky root disease severity in the present study.     

Leaf beetle larvae,Plagiodera versicolora (Coleoptera: Chrysomelidae), show decreased performance on uninfested host plants exposed to airborne factors from plants infested by conspecific larvae

Undamaged plants are known to suffer less damage from herbivores when previously exposed to airborne factors from neighboring plants that are either infested or artificially damaged. However, to date, the effects of such a defensive phenomenon on performance of herbivorous insects have not been clearly shown. Here, we studied such effects in an interaction between a willow plant, Salix eriocarpa Franchet et Savatier (Salicales: Salicaceae), and a specialist leaf beetle, Plagiodera versicolora (Laicharting) (Coleoptera: Chrysomelidae). In a wind tunnel, uninfested willow plants were placed downwind of willow plants infested by leaf beetle larvae for 4 days. As a control, we placed uninfested plants downwind of uninfested plants in the tunnel. After exposure, downwind plants were served to leaf beetle larvae. Pupal weight, larval survival rates, and the leaf area consumed by larvae all decreased significantly, and larval developmental duration increased significantly, when larvae fed on willow plants downwind of infested plants were compared with those downwind of uninfested plants. These results showed that airborne factors from infested willow plants negatively affected the performance of leaf beetle larvae. Further studies are needed to identify the active factor(s) from the infested willow plants affecting the performance of leaf beetle larvae.     

Density, dispersal, and feeding impact of western flower thrips (Thysanoptera: Thripidae) on flowering chrysanthemum at different spatial scales

Abstract.  1. This study evaluated the effect of dispersal on the density and feeding impact of a phytophagous insect in relation to the spatial distribution of its host plants.
2. The interaction between density, dispersal, and feeding impact of western flower thrips on flowering chrysanthemum was quantified at three spatial scales, with infested and uninfested plants either isolated in 0.25 m² individual cages, or enclosed together in 2.25 m² communal cages or 75 m² greenhouses.
3. In individual cages, the rate of dispersal from chrysanthemum plants to blue sticky traps increased with the density of thrips for females but not males. Uninfested plants consistently had fewer thrips when they were individually caged rather than enclosed with plants infested with adults, indicating that dispersal mediates inter-plant distribution of thrips.
4. The feeding impact of thrips on inflorescences was evaluated using the absorbance of ethanol extracts at wavelengths characteristic of yellow carotenoid pigments associated with chrysanthemum inflorescences (415, 445, and 472 nm). Increasing absorbance of extracts with increasing density of thrips per inflorescence suggests that feeding by thrips results in ruptured cells leaching carotenoid pigments.
5. In communal cages, the distribution of thrips was uniform for infested and uninfested plants, whereas the density and feeding impact of thrips in greenhouses were higher for infested than uninfested plants. These results suggest that short-range dispersal by adults homogenises the density and feeding impact of thrips among host plants only on a small spatial scale.     

Effect of Mulch Surface Color on Root-knot of Tomato Grown in Simulated Planting Beds

The effect of different-colored polyethylene mulches on quantity and spectra of reflected light, plant morphology, and root-knot disease was studied in tomato (Lycopersicon esculentum) grown in simulated planting beds. Tomato plants were inoculated with Meloidogyne incognita at initial populations (Pi) of 0, 1,000, 10,000, or 50,000 eggs/plant, and grown in a greenhouse for 50 days over white, red, or black mulch. Soil temperature was kept constant among the mulch treatments by placing an insulation barrier between the colored mulch and the soil surface. Soil temperature varied less than 0.5 °C between soil chambers at solar noon. Tomatoes grown over white mulch received more reflected photosynthetic light and had greater shoot weights (27%), root weights (32%), and leaf area (20%) than plants grown over black mulch. Plants grown over red mulch received a higher far-red-to-red ratio in the reflected light. Mulch color altered the plant''s response to root-knot nematode infection by changing the distribution of mass in axillary shoots. At high Pi, axillary leaf area and leaf weight were greater in tomato grown over white mulch than when grown over red mulch. The root-gall index was lower for plants grown over white mulch than similar plants grown over red mulch.     

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.