We quantified the life table parameters and predation capacity of a generalist predatory mite, Typhlodromus bagdasarjani Wainstein and Arutunjan on five monotypic diets, including Tetranychus urticae Koch (TSSM) eggs in the presence (SW) and absence (SN) of webs, Trialeurodes vaporariorum Westwood (GHWF) eggs (G), honeydew (H), and maize pollen (M) as well as three mixed diets, including SN + M, SN + G, and G + M. Our results showed that the individuals fed on the mixed diets had a considerably shorter developmental time and pre-oviposition period (APOP), higher oviposition days, higher fecundity and population growth rate than those raised on the monotypic diets. Furthermore, we found that the mixed diet of TSSM and GHWF eggs was the most favorable diet, resulted in the highest fecundity and population growth rate, shortest developmental time and APOP. While TSSM eggs alone in the presence of webs and honeydew were the worst diets resulted in the longest developmental time, lower oviposition day, higher fecundity and population growth rate. Our data determined that TSSM has more nutritional benefits than GHWF for T. bagdasarjani. We observed the positive effects of pollen addition to prey on the predatory mite's immature and adult life-history characters; however, it reduced the predation rate. Overall, maize pollen could enhance ecosystem services provided against spider mites and whiteflies by positively impacting the increase of T. bagdasarjani population. This predator may be more effective when two prey species are available than when only one species is present.

Cold storage effects on the female predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on Tetranychus urticae Koch eggs for different time periods (5, 10, 20 and, 30 days) at 5 or 25 °C (control) on development and life table parameters were examined. Female adult duration and female total longevity were not influenced by the period of cold storage. The minimum mean female total longevity (28.1 ± 0.32 day) was observed in the 30-day treatment. The oviposition period decreased with increasing cold storage duration. All life table parameters of S. longicornis demonstrated a significant difference across treatments. Our results demonstrated that the female adult of S. longicornis could be maintained at 5 °C for 5-days with minimal reduction in the life-history process. This would be beneficial in the storage and mass production of S. longicornis in biocontrol programs involving T. urticae.

Better performance of generalist predators, as well as an increase in their density, may be an incentive factor in the ability of the predators to exploit more than one food item or mixed diets. In this study, the effects of four pollen grains (cedar, pear, apricot, and pistachio) when provided to Neoseiulus californicus in mixed diets with prey, Tetranychus urticae, were evaluated. The result indicated that the fastest female developmental time was observed on pistachio pollen + T. urticae, together with apricot pollen + T. urticae. Females reared on the mixed diet comprising pistachio pollen reflected the longest total life span duration, while the shortest total life span was observed in those on the diet that included pear pollen. Furthermore, the lowest fecundity, as well as the shortest reproduction period, was determined on the diets that included pear pollen, while the highest fecundity and the longest reproduction period were observed in pistachio pollen + T. urticae. In addition, the intrinsic (r) and finite rate of increase (λ), net (R0) and gross (GRR) reproductive rates were highest in pistachio pollen + T. urticae. These findings have important implications for developing a comprehensive biological control program of T. urticae, which will be discussed.

Amblyseius swirskii Athias-Henriot is a well-known predator that is used for controlling the population of two-spotted spider mites (TSSM), Tetranychus urticae Koch, and greenhouse whitefly (GHWF), Trialeurodes vaporariorum Westwood, in strawberry greenhouses. To find the effective factors that influence the efficiency of this predator, the predation rates of A. swirskii fed on (Ι) TSSM in the presence and absence of the pollen, webbing, and GHWF, as well as on (II) GHWF in the presence and absence of the pollen, and GHWF-produced honeydew were determined. Furthermore, developmental time, fecundity, and population growth rate of this predator under the same conditions were measured. Our results showed that A. swirskii was able to reduce TSSM population, while the spider mite webbing had an adverse effect on the performance of the predator. Therefore, the presence of the predator population at the time of the infestation is crucial to the success of biological control. It can be concluded that the alternative food sources such as pollen and GHWF-produced honeydew play an important role in maintaining the predator population in the absence of pests. Moreover, the results indicate that using the pollen and another pest along with the target pest can promote the predator density. A. swirskii consumed lower numbers of TSSM when concurrently offered with GHWF and/or maize pollen, and lower numbers of GHWF in the presence of pollen. On the other hand, in the presence of alternative food or alternative prey, the fecundity of the predator was much higher.

In the present study, the susceptibility of different developmental stages (eggs, larvae, protonymphs, deutonymphs and adults) of Tetranychus urticae Koch to the entomopathogenic fungi Beauveria bassiana (Balsamo-Crivelli) Vuillemin and Metarhizium anisopliae (Metchnikoff) Sorokin was evaluated in the laboratory. At each developmental stage, four concentrations (3 × 105, 1 × 106, 3 × 106 and 1 × 107 conidia/ml) of both fungi were sprayed. Egg viability and motile-stage mortality varied among the fungal isolates and conidial concentrations. The highest conidial concentration (1 × 107 conidia/ml) significantly reduced the viability of eggs and increased the mortality of motile stages. However, deutonymphs and adults were more susceptible to fungal infection than larvae and protonymphs. The lethal concentration values to 50% (LC50) and 90% mortality (LC90) varied with the fungal isolates and developmental stages. The results show the prospects of B. bassiana and M. anisopliae for the control of T. urticae.

Among the herbivorous arthropods that feed on strawberry, the most important are the two-spotted spider mite (TSSM), Tetranychus urticae Koch, and several species of aphids. Mites and aphids belong to different guilds that coexist in the field and feed on the undersides of strawberry leaflets. However, the occurrence of large numbers of individuals of both species on the same leaflet is rarely recorded. We hypothesize that negative interactions between TSSM and aphids explain the intraplant distribution of these herbivores. We first examined the spatial coincidence of both herbivores in the field. Under experimental conditions, we then analyzed: (i) the rate of increase of TSSM and the aphid Chaetosiphon fragaefolii (Cockerell), growing individually and together; (ii) the effect of honeydew on TSSM preference; and (iii) the effect of previous strawberry leaflet damage by TSSM on C. fragaefolii preference. The proportion of TSSM that coincided with at least one aphid decreased as the percentage of leaflets with TSSM increased. The spatial coincidence index between aphids and TSSM increased together with the percentage of TSSM-infested leaflets. TSSM showed both a lower rate of increase when they shared the same leaflet with C. fragaefolii and lower fecundity on strawberry discs with honeydew. The rate of increase of C. fragaefolii did not change on co-occupied leaves, but the aphid species moved to the other side of leaflets shared with TSSM. Negative interactions resulting in a tendency for species to avoid each other, such as demonstrated herein, can affect distribution and performance of herbivorous arthropods.

A Belgian field strain (MR-VP) of Tetranychus urticae (Koch) (Acari: Tetranychidae) exhibits different levels of resistance to four frequently used METI (mitochondrial electron transport inhibitor)-acaricides, i.e. tebufenpyrad, fenpyroximate, pyridaben and fenazaquin. Resistance factors for these compounds were 184, 1547, 5971 and 35, respectively. A 23.5-fold increase in 7-ethoxy-4-trifluoromethylcoumarin O-deethylation activity suggested that metabolic resistance through elevated levels of cytochrome P450 dependent monooxygenase-activity is a possible resistance mechanism.

However, synergism studies with different metabolic inhibitors revealed some contrasting resistance mechanisms between the METI-acaricides. Tebufenpyrad resistance could only be synergized after pre-treatment with the monooxygenase inhibitor piperonyl butoxide (PBO), whereas pyridaben resistance was strongly synergized both by PBO and the esterase inhibitor S,S,S-tributylphosphorotrithioate (DEF). Resistance levels to fenpyroximate could neither be suppressed by PBO nor by DEF. Although METI-acaricides are structurally related, these findings probably reflect a different role of esterases and mono-oxygenases in metabolic detoxification between these compounds. The overall lack of synergism by diethylmaleate (DEM) suggests that glutathione-S-transferases are not an important factor in resistance to METIs.

Reciprocal crosses between susceptible females and resistant males showed no maternal effect, and resistance to METI-acaricides was inherited generally as a dominant trait. Backcrosses with F1 females revealed striking differences in the mode of inheritance. Although resistance to fenpyroximate and pyridaben was under monogenic control, resistance to tebufenpyrad was under control of more than one gene.

A survey of the mite fauna associated with Amaranthus cruentus L. (amaranth), Solanum macrocarpon L. (Gboma) and S. aethiopicum L. (African eggplant), three major indigenous vegetables produced in Benin, was carried out from August to October 2004 both at IITA-Benin station and on a vegetable farm at Togba in Abomey-Calavi area. Thirty-three mite species belonging to 12 families were found on the three vegetables. These species included phytophagous mites, predatory mites of the family Phytoseiidae, and another group whose feeding habits were not clear. The following phytophagous mites were found: Tetranychus urticae Koch and T. ludeni Zacher, in the family Tetranychidae; Polyphagotarsonemus latus (Banks) and another unidentified mite species, in the family Tarsonemidae. The two Tetranychus species were present on all three vegetables whereas tarsonemids were found only on the two solanaceous plants. Polyphagotarsonemus latus was the most dominant pest during the course of the experiments. It is the major mite pest on solanaceous plants, especially on Gboma in vegetable farms, where broad-spectrum pesticides harmful to natural enemies are used. The phytoseiids group was the most diversified with 16 species out of the 33 identified and more predominant in IITA plots where no pesticides were applied, compared to Togba plots where pesticides were regularly applied on nearby plots. They seem to better control P. latus on Gboma than on African eggplant. Other mites identified on the three vegetables belong to the following families: Acaridae, Tydeidae, Erythraeidae, Cunaxidae, Anystidae, Ascidae, Bdellidae, Uropodidae and Oribatidae.

The resistance of 63 tomato (Lycopersicon esculentum Mill.) accessions to the twospotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae), was investigated in screen house experiments and compared to Money Maker, a T. urticae-susceptible variety widely grown in Kenya. The number of motile mite stages 12 days after inoculation with 5 adult female mites was significantly lower than in the control variety (Money Maker) in seven accessions (Marglobe, Roma-VF, 94 RT 330, Continental Michel, Early Pearson, ARP 366–4 and 94 RT 316). Egg numbers were significantly lower than in the control in 14 accessions (Marglobe, Cal-J-VF, Roma-VF, Beauty, 95 RT 315, 93 KT 20, EC.3504,94 RT 313, EC-1193, Continental Michel, Early Pearson, ARP 366–4,94 RT 316 and Malawi Local 3). This study reveals the existence of resistance to T. urticae in the tomato accessions.

The effects of four different neem formulations (Neemros®, Neemroc EC®, Neemroc Combi and Saroneem) and a combination of Neemros® with a synthetic acaricide (Mitac®) on the twospotted spider mite (Tetranychus urticae Koch) were compared with Mitac® on tomato (Lycopersicon esculentum Mill.) leaf discs in the laboratory, The following LC50 were determined: Neemroc EC® 12.9 ml/1, Saroneem 5.8 ml/1, Neemroc Combi 1.0 ml/1 and Mitac® + Neemros® 1 ml/1 + 17.6 g/1. No LC50 was determined for Neemros® since the highest mortality observed was 11.4 %. The combination of Mitac® and Neemros® resulted in the highest mortality after 24 hours (83.3 %), followed by Neemroc EC® (78.3 %), Saroneem (53.4 %), Mitac® (50.8 %), Neemroc Combi (38.9 %), the control (4.5 %) and Neemros® (0.0 %). All neem formulations also caused repellence and oviposition deterrence in T. urticae.

The unsaponifiable matter and fatty acid methyl esters of the petroleum ether extract of seven plants with known acaricidal activity were fractionated and identified by GC chromatography, and their biological activity against the two-spotted spider mite, Tetranychus urticae Koch. (Acariforms: Tetranychidae) assayed. In general, unsaponifiable matter showed higher acaricidal activity than the saponifiable matter. The unsaponifiable matter of Dodonaea viscosa leaves was the most toxic and that of Callistemon lanceolatus leaves the least toxic. The saponifiable matter (fatty acids) of Curcuma longa was the most potent.

Green marine algae (Codium sp.) was extracted sequentially with different organic solvents on cold. Lima bean leaf discs treated with the different extracts were offered to adult female T. urticae for 96 hr and the corrected percentage mortality of the females was calculated. The toxicity of the different extracts to the eggs was also recorded. Petroleum ether extract of this seaweed was highly toxic to females at 4 g/ml. At 1 g/ml ca. 48% of the individuals were killed. Chloroform and ethyl alcohol extracts were found to be poorly effective against the females even at high concentrations (4 g/ml) where less than 50% of the individuals died after 96 hr. Toxicity of crude extracts to the egg stage was less pronounced and chloroform extract was found to be more efficient than the other extracts tested.

The green cassava mite, Mononychellus tanajoa (Bondar) and the red spider mite, Tetranychus urticae Koch infest all varieties of cassava in Sierra Leone. Both tetranychid species are widely distributed in the country and are causing severe damage to the crop mainly in the major cassava producing areas in the north-western regions. M. tanajoa caused chlorosis and 91° loss in photosynthetic area of the attacked leaves and defoliation of the plant either by acting alone or in concert with T. urticae. Late planted crop was particularly vulnerable to the infestation. M. tanajoa and T. urticae appeared to avoid severe interspecific competition on the plant by habitat stratification.