Foraging on and Consumption of Two Species of Papaya Pest Mites

BIOLOGICAL CONTROLÑPARASITOIDS AND PREDATORS Foraging on and Consumption of Two Species of Papaya Pest Mites, Tetranychus kanzawai and Panonychus citri (Acari: Tetranychidae), by Mallada basalis (Neuroptera: Chrysopidae)

LING LAN CHENG,1,2 JAMES R. NECHOLS,1 DAVID C. MARGOLIES,1 JAMES F. CAMPBELL,1,3 4 5 5 PING SHIH YANG, CHIEN CHUNG CHEN, AND CHIU TUNG LU

Environ. Entomol. 38(3): 715Ð722 (2009) ABSTRACT Tetranychus kanzawai Kishida and Panonychus citri (McGregor) are two major acarine pests of the principal papaya variety in Taiwan, and they often co-occur in the same papaya screenhouses. This study measured prey acceptability, foraging schedule, short-term consumption rate, and handling time of larvae of a domesticated line of the green lacewing, Mallada basalis (Walker), in no-choice tests with different life stages of these two mite pests. After a period of prey deprivation, all three larval instars of M. basalis exhibited a high rate of acceptance of all life stages of both T. kanzawai and P. citri. In 2-h trials, second- and third-instar predators foraged actively most of the time, whereas Þrst instars spent Ϸ40% of the time at rest. Consumption increased and prey handling time decreased as predator life stage advanced and prey stage decreased. Third-instar lacewings consumed an average of 311.4 T. kanzawai eggs (handling time: 6.7 s/egg) and 68.2 adults (handling time: 58.8 s/adult), whereas Þrst instars consumed 19.6 eggs (handling time: 23.6 s/egg) and 4.0 adults (handling time: 633.4 s/adult). M. basalis generally consumed more P. citri than T. kanzawai. Except for prey eggs, handling times of T. kanzawai were generally longer than those of P. citri by all M. basalis instars. Handling times were shorter, and consumption were greater, at the higher P. citri density than at the lower one, whereas there were generally no signiÞcant differences in prey acceptability and foraging time between those two densities. This study suggests that M. basalis larvae may have high potential for augmentative biological control of mites on papayas.

KEY WORDS phytophagous mites, predatorÐprey interaction, feeding behavior, predatory potential, biological control

Papaya, Carica papaya L., is an important fruit crop in Two tetranychid mites (Acari: Tetranychidae), the Taiwan with annual production estimated at Ϸ126,500 Kanzawa spider mite, Tetranychus kanzawai Kishida, tons (Anonymous 2006). The principal papaya variety and the citrus red mite, Panonychus citri (McGregor), in Taiwan is ÔTainung No. 2Ј. However, this cultivar is are major pests of papayas in screenhouses (Ho et al. susceptible to the papaya ringspot potyvirus (Lin et al. 1997). Both occur throughout the year in Taiwan, with 1989), which is one of the most destructive diseases populations peaking in dry months of October through affecting papaya (Purcifull et al. 1984). Cultivation of May (Cheng 1966, Huang et al. 1997). T. kanzawai papayas in screenhouses has been developed to help feeds on cell chloroplasts on the under surface of the protect this crop from aphids, which serve as vectors leaf, causing the upper surface of the leaf to develop for papaya ringspot virus. Demonstrated levels of pro- a characteristic whitish or yellowish stippling, which tection have reached 97% (Shi et al. 1990). Therefore, joins and becomes brownish as mite feeding continues most papayas in Taiwan are now grown in screen- (Yamada and Tsutsumi 1990, Zhang 2003). Heavy houses. However, the unventilated, warm conditions damage causes wilting and defoliation. Panonychus in screenhouses favor outbreaks of acarine pests (Hao citri feeds on both sides of leaves and produces a et al. 1996). stippled appearance initially, which develops into pale patches later. With continuous feeding and damage, 1 Department of Entomology, Kansas State University, Manhattan, the leaves become gray, silver, or yellow (Zhang KS 66506. 2003). 2 Corresponding author: Division of Applied Zoology, Taiwan Ag- ricultural Research Institute, 189 Chung Cheng Rd., Wufeng, Control of mite pests on papayas depends mainly on Taichung 413, Taiwan (e-mail: [email protected]). chemical applications. However, the intensive appli- 3 USDAÐARS GMPRC, 1515 College Ave., Manhattan KS 66502. cation of miticides, and the short life cycle and high 4 Department of Entomology, National Taiwan University, No. 1, reproductive rates of mites, have led to the develop- Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan. 5 Division of Applied Zoology, Taiwan Agricultural Research In- ment of resistance to many registered miticides in stitute, 189 Chung Cheng Rd., Wufeng, Taichung 413, Taiwan. both the Kanzawa and citrus red mite (Cranham and

0046-225X/09/0715Ð0722$04.00/0 ᭧ 2009 Entomological Society of America 716 ENVIRONMENTAL ENTOMOLOGY Vol. 38, no. 3

Helle 1985, Yamamoto et al. 1996, Goka 1998). The Larvae were reared on a microencapsulated artiÞcial number of miticides that can be used is further limited diet consisting of honey, sugar, BrewerÕs yeast, yeast because many miticides produce unacceptable phy- autolysate, casein hydrolysate, egg yolk, honey bee totoxicity to papayas (Lo 2002). Therefore, it is nec- larvae, and distilled water (Lee 1994, 1995). The mi- essary to search for alternative approaches for con- crocapsules had a diameter of 465 ␮m and a thickness trolling papaya mite pests. of 10 ␮m. Following the methods developed by Lee The green lacewing, Mallada basalis (Walker) (2003), larvae were reared in plastic pans (40 by 30 by (Neuroptera: Chrysopidae), is common in agricultural 10.5 cm [L by W by H]). Corrugated paper rolls (10 Þelds in Taiwan. The adults feed on nectar and hon- cm diameter and 1.5 cm thick) were Þrst placed in eydew, but larvae are generalist predators (Wu 1995). each pan, and then they received 2 Tbs sawdust, 25 ml Previous studies have suggested the potential of this microencapsulated diet, and Ϸ1,000 green lacewing lacewing species as a biological control agent of sev- eggs. Subsequently, diet was added three more times eral species of arthropod pests, including Phyllocnistis at 3-d intervals in the following amounts: 75, 100, and citrella Stainton, Aphis spp., Nipaecoccus ﬁlamentosus 25 ml. These amounts corresponded to relative feed- (Cockerell), Diaphorina citri Kuwayama, and P. citri ing rates of larvae during growth and development. To on citrus; A. gossypii Glover on sweet pepper; T. urticae prevent lacewing larvae from escaping and to avoid Koch and T. kanzawai on strawberry; and P. citri on invasion by predators such as ants and spiders, a piece Indian jujube (Lo 1997, Lu and Wang 2006). M. basalis of 200 mesh white screen was taped over the top of can be successfully mass produced using a microen- each rearing pan. capsulated artiÞcial diet in a cost-effective manner Most larvae pupated on or inside the corrugated (Lee 1994, 1995, 2003). Cold storage techniques have paper rolls after which they were moved to a black also been established for maintaining various stages acrylic box (45 by 45 by 45 cm) for collection of for shipping and scheduled releases (Wu 1992). In emerging adults. The lid of the box was Þtted with a addition, tolerance of M. basalis to some insecticides, 15 by 20 cm (diameter by height) clear acrylic cylin- fungicides, and acaricides has been shown (Tzeng and der. On emergence, lacewing adults were attracted to Kao 1996, Lo 2002). For all of these reasons, M. basalis light and would ßy up into the cylinder. The adults may be a compatible, viable candidate species for use were placed in another acrylic cylinder with a piece in integrated pest management (IPM) programs on of white paper attached to the inside wall for ovipo- papaya. sition. The white paper was changed once every day. Although M. basalis has been evaluated in the Þeld Adult lacewings were maintained on a diet of BrewerÕs (Lo 1997), little is known about its prey selection and yeast and honey (1:1). To feed adults, diet was applied feeding behavior. Knowledge of predator feeding be- to a section of plastic slide, which was hung inside the havior is crucial for evaluating M. basalis as a biological cylinder. Water was provided by wetting a cotton ball. control agent of papaya mites. This study investigated aspects of the feeding behavior and predatory poten- General Experimental Procedures. Tests with pred- tial (i.e., foraging schedule, prey acceptance, handling ators and prey were done on individual pieces of times, and consumption rates) of M. basalis on T. papaya leaf, which were ßoated in water with the kanzawai and P. citri in the laboratory. lower leaf surface facing up in a 9-cm-diameter plastic petri dish. Leaf areas ranged from 225 to 3,160 mm2, depending on mite life stage. These areas maintained Materials and Methods the test densities and provided enough prey for the predator. SpeciÞed numbers of T. kanzawai or P. citri Arthropod and Plant Cultures and one M. basalis larva were placed on the leaf with Papayas. Papaya seedlings (Carica papaya L., a Þne-hair paint brush. The experimental setting kept ÔTainung No. 2Ј) were purchased from a commercial the lacewing and the mites on the leaf throughout the nursery 3Ð4 wk after germination. The seedlings were observational period. The feeding activities of the transferred individually to 9-cm-diameter pots and lacewing larvae were continuously observed under a maintained in a room at 26 Ϯ 2ЊC, 70 Ϯ 10% RH, and microscope for 2 h, and all experimental observations a photoperiod of 14:10 (L:D) until they were Ϸ25 cm were carried out between 1000 and 1800 hours. Light tall and suitable for rearing mites. The seedlings were was provided by a ßuorescent illuminator (KL 1500 watered twice a week and were not fertilized. electronic; SCHOTT, Auburn, NY) (Ϸ95 lux), and Mites. Tetranychus kanzawai and P. citri were col- room temperature was 26 Ϯ 2ЊC. Tests were done with lected from papaya plantations in the Nantou area of all combinations of the three lacewing instars and the Taiwan in 2003 and maintained in separate rooms on four mite instars (egg, larva, nymph, adult female) for papaya seedlings at 26 Ϯ 2ЊC, 70 Ϯ 10% RH, and a a total of 12 treatment combinations for each mite photoperiod of 14:10 (L:D). species. Lacewing larvae were tested in the Þrst day of Green Lacewings. The green lacewings used in this each stadium. Before testing, they were held in indi- study were from a colony of M. basalis that had been vidual vials without food for 2, 4, or 8 h for Þrst, second maintained in the laboratory continually since 1999, and third instars, respectively. Preliminary tests indi- when Þeld collections were made. For rearing and cated that these periods of food deprivation triggered experiments, lacewings were kept in a room at 26 Ϯ lacewing foraging immediately after release, but with- 2ЊC, 70 Ϯ 10% RH, and a photoperiod of 14:10 (L:D). out causing a weakened foraging ability. June 2009 CHENG ET AL.: PREDATION OF M. basalis ON PAPAYA PEST MITES 717

(5 ؍ Table 1. Foraging behaviors (mean ؎ SE) of M. basalis larvae preying on T. kanzawai on papaya (n

M. basalis Prey Total foraging Total no. of prey Mite stage Handling timed (s) instar acceptabilitya timeb (min) consumedc First instar Egg 0.73 Ϯ 0.13a 24.50 Ϯ 4.01a 19.6 Ϯ 2.0a 23.59 Ϯ 2.43a Larva 0.66 Ϯ 0.08a 48.60 Ϯ 12.99ab 19.6 Ϯ 5.3a 60.95 Ϯ 5.41a Nymph 0.83 Ϯ 0.08a 88.29 Ϯ 11.24c 21.6 Ϯ 4.9a 120.19 Ϯ 24.09a Adult 0.59 Ϯ 0.09a 75.85 Ϯ 7.47bc 4.0 Ϯ 0.8b 633.43 Ϯ 221.77b Second instar Egg 0.93 Ϯ 0.02a 88.09 Ϯ 12.73a 135.8 Ϯ 26.3a 9.41 Ϯ 2.74a Larva 0.84 Ϯ 0.06a 110.73 Ϯ 5.52ab 73.6 Ϯ 5.6b 38.39 Ϯ 1.25b Nymph 0.85 Ϯ 0.07a 95.24 Ϯ 10.20ab 53.4 Ϯ 12.2bc 59.57 Ϯ 7.14b Adult 0.69 Ϯ 0.06a 115.77 Ϯ 4.23b 26.0 Ϯ 3.7c 170.54 Ϯ 30.73c Third instar Egg 0.94 Ϯ 0.03a 110.04 Ϯ 8.84a 311.4 Ϯ 26.7a 6.67 Ϯ 0.74a Larva 0.79 Ϯ 0.04a 116.22 Ϯ 3.06a 138.2 Ϯ 11.3b 18.76 Ϯ 1.65b Nymph 0.89 Ϯ 0.04a 119.32 Ϯ 0.68a 139.6 Ϯ 14.2b 27.92 Ϯ 2.94c Adult 0.92 Ϯ 0.03a 118.38 Ϯ 0.99a 68.2 Ϯ 4.9c 58.78 Ϯ 2.91d

The mite densities used in various tests were as Data Analyses. Data for various comparisons were follows: 33 eggs, 27 larvae, 19 nymphs, or 13 adult subjected to a variance check to determine whether females per 100-mm2 leaf area. These densities were they met the assumption that the SDs of all categories selected so that distances the lacewings needed to subjected to the same comparisons were equal. In travel to encounter a prey were similar among the cases where the data were shown to have unequal tests. The total number of mites provided in each test variance (e.g., handling times comparisons), square was 1.5-fold the amount that a lacewing usually could root transformations were performed before analysis. take during a 2-h period. There were Þve replications Subsequently, normally distributed (or normalized) for each predatorÐprey combination. data were analyzed using analysis of variance Data collected included a sequential record of prey (ANOVA), and non-normally distributed data were handling times (measured as the time from a prey analyzed with the Kruskal-Wallis test. Means were encounter to consumption; handling times were av- separated for signiÞcance using the Fisher protected eraged for each individual predator), periods of active least signiÞcant difference (LSD) procedure. For foraging (searching plus handling prey) and rest, and pairwise comparisons, a t-test assuming equal variance the number of prey consumed (including both fully was used to analyze normally distributed data, a Mann- and partially consumed). Prey acceptability was com- Whitney test was used to analyze non-normally distrib- puted as the proportion of encountered prey that were uted data for the comparisons between different mite attacked and consumed. species, and a t-test assuming unequal variance was used The spatial distributions of T. kanzawai and P. citri for comparisons between the two mite densities. The on papaya differ in the Þeld based on observations signiÞcance level was set at P Ͻ 0.05. All analyses were (L.C.). T. kanzawai has a clumped distribution, conducted using STATGRAPHICS Centurion XV soft- whereas P. citri are more evenly spaced over the ware, 2005 (Statpoint, Herndon, VA). leaves. Relative abundance also differs between the two species, with P. citri occurring at lower densities Results in nature than T. kanzawai. The mite densities we used in comparisons between species were similar but rep- Prey Acceptability. All larval stages of M. basalis resent a moderately high-Þeld density for T. kanzawai exhibited moderate to high rates of prey acceptability and an extremely high density for P. citri. To examine for various life stages of T. kanzawai (59Ð94%) and P. responses of lacewing larvae to more representative citri (62Ð100%). For any given M. basalis larval instar, densities of the latter mite, tests with P. citri at what there were no signiÞcant differences in prey accept- we termed “low” density (i.e., 1.7 eggs, 1.4 larvae, 0.9 ability among various life stages of each mite species nymphs, and 0.6 adult females per 100-mm2 leaf area, (Tables 1Ð3). However, prey acceptability of adult T. and papaya leaves of 14,200Ð17,400 mm2) were also kanzawai was signiÞcantly higher for third-instar M. carried out; these were Ϸ1/20 of the high densities and basalis (0.92 Ϯ 0.03) than for Þrst (0.59 Ϯ 0.09) or represent moderate densities of P. citri occurring in second instars (0.69 Ϯ 0.06; F ϭ 6.53; df ϭ 14; P ϭ 0.01). the Þeld. Observations for the various predatorÐprey Otherwise, prey acceptability did not differ among M. combinations (3 predator instars ϫ 4 mite instars ϫ 2 basalis instars for other T. kanzawai life stages or for mite species ϫ 2 mite densities [for P. citri] ϫ 5 any of the P. citri life stages. replications) were blocked over time, and the order of Acceptance generally did not differ between T. kan- observations was randomized for each block. zawai and P. citri for the various M. basalis instars 718 ENVIRONMENTAL ENTOMOLOGY Vol. 38, no. 3

(5 ؍ Table 2. Foraging behaviors (mean ؎ SE) of M. basalis larvae preying on P. citri at high density on papaya (n

M. basalis Prey Total foraging Total no. of prey Mite stage Handling timed (s) instar acceptabilitya timeb (min) consumedc First instar Egg 0.97 Ϯ 0.01a 100.53 Ϯ 6.20a 83.4 Ϯ 5.5a 32.33 Ϯ 0.93a Larva 0.91 Ϯ 0.04a 79.71 Ϯ 9.50a 36.6 Ϯ 5.1b 53.09 Ϯ 5.90a Nymph 0.91 Ϯ 0.04a 70.36 Ϯ 13.65a 18.2 Ϯ 3.5c 123.42 Ϯ 23.50b Adult 0.62 Ϯ 0.14a 87.40 Ϯ 4.57a 12.2 Ϯ 2.2c 240.77 Ϯ 37.75c Second instar Egg 0.94 Ϯ 0.02a 116.32 Ϯ 3.68a 150.8 Ϯ 15.6a 18.78 Ϯ 1.31a Larva 0.96 Ϯ 0.02a 112.49 Ϯ 7.51a 114.8 Ϯ 16.6b 25.06 Ϯ 2.05b Nymph 0.96 Ϯ 0.01a 105.64 Ϯ 7.24a 63.2 Ϯ 5.6c 52.64 Ϯ 3.41c Adult 0.76 Ϯ 0.08b 118.32 Ϯ 0.76a 43.2 Ϯ 3.1c 83.86 Ϯ 2.72d Third instar Egg 0.98 Ϯ 0.01a 116.91 Ϯ 2.11a 303.0 Ϯ 27.8a 9.35 Ϯ 0.75a Larva 0.96 Ϯ 0.02a 118.35 Ϯ 0.94a 173.0 Ϯ 22.2b 16.00 Ϯ 1.59a Nymph 0.97 Ϯ 0.01a 114.29 Ϯ 4.14a 117.8 Ϯ 6.2bc 30.11 Ϯ 1.22b Adult 0.94 Ϯ 0.03a 116.57 Ϯ 1.34a 114.0 Ϯ 14.8c 33.62 Ϯ 7.38b

Total observation duration ϭ 2 h. Means within the same column of the same M. basalis instar followed by the same letter are not signiÞcantly different at P Ͻ 0.05 (FisherÕs protected LSD test; STATGRAPHICS Centurion XV, 2005). Data of handling time before analysis were subject to square root transformation; the untransformed means are presented. a Proportion of encountered prey that are attacked and consumed (including both fully and partially consumed). b The time spent searching and handling the prey. c Number of prey that are fully or partially consumed. d The time from a prey encounter to consumption. except that Þrst-instar (t ϭ 2.83; df ϭ 4; P ϭ 0.02) and (Tables 1Ð3) except that Þrst instars foraged longer for third-instar (W ϭϪ11.5; df ϭ 4; P ϭ 0.02) predators later-instar T. kanzawai than for earlier stages (F ϭ accepted a greater proportion of P. citri larvae (Þrst: 8.73; df ϭ 19; P ϭ 0.001; Table 1). 0.91 Ϯ 0.04; third: 0.96 Ϯ 0.02) than T. kanzawai larvae A comparison of lacewing foraging times between (Þrst: 0.66 Ϯ 0.08; third: 0.79 Ϯ 0.04). When P. citri the two mite species showed that there were generally were present at the lower density (1.7 eggs, 1.4 larvae, no differences, except that Þrst- (t ϭ 9.83; df ϭ 4; P Ͻ 0.9 nymphs, or 0.6 adult females per 100-mm2 leaf 0.001) and second- (W ϭϪ10.5; df ϭ 4; P ϭ 0.03) area), which represents a moderate density in the instar predators actively foraged for a signiÞcantly Þeld, M. basalis exhibited prey acceptability rates that longer time on P. citri eggs than on T. kanzawai eggs. were mostly similar to those exhibited when P. citri The difference in foraging time for eggs of the two were present at the higher density (33 eggs, 27 larvae, mite species was greater for Þrst-instar M. basalis (P. 19 nymphs, or 13 adult females per 100-mm2 leaf area). citri: 100.53 Ϯ 6.20 min; T. kanzawai: 24.50 Ϯ 4.01 min) Foraging Time. In 2-h trials, second- and third- than for second instars (P. citri: 116.32 Ϯ 3.68 min; T. instar lacewings spent most of their time actively for- kanzawai: 88.09 Ϯ 12.73 min). There were generally no aging (mean ϭ 112.3 min), whereas Þrst instars spent P. citri density-related differences in foraging time signiÞcantly (P Ͻ 0.05) less time actively foraging among M. basalis instars. However, Þrst- and second- (mean ϭ 71.2 min) and relatively more time at rest instar M. basalis took signiÞcantly longer to forage on (Tables 1Ð3). The time spent by M. basalis foraging P. citri adults at high density (Þrst: 87.40 Ϯ 4.57 min; generally did not differ among various mite life stages second: 118.32 Ϯ 0.76 min) than at low density (Þrst:

(5 ؍ Table 3. Foraging behaviors (mean ؎ SE) of M. basalis larvae preying on P. citri at low density on papaya (n

M. basalis Prey Total foraging Total no. of prey Mite stage Handling timed (s) instar acceptabilitya timeb (min) consumedc First instar Egg 0.96 Ϯ 0.04a 77.53 Ϯ 12.20a 9.8 Ϯ 1.5a 49.78 Ϯ 3.59a Larva 1.00 Ϯ 0.00a 60.53 Ϯ 10.26a 7.2 Ϯ 1.7a 73.91 Ϯ 9.85b Nymph 0.94 Ϯ 0.04a 79.78 Ϯ 20.55a 8.4 Ϯ 1.6a 107.75 Ϯ 11.99b Adult 0.87 Ϯ 0.08a 61.36 Ϯ 9.68a 5.4 Ϯ 1.3a 196.30 Ϯ 23.49c Second instar Egg 0.93 Ϯ 0.02a 117.30 Ϯ 1.04a 42.0 Ϯ 5.6a 26.17 Ϯ 2.00a Larva 0.96 Ϯ 0.02a 116.57 Ϯ 1.40a 31.8 Ϯ 2.8ab 29.46 Ϯ 2.66a Nymph 0.95 Ϯ 0.01a 112.93 Ϯ 4.50a 28.8 Ϯ 5.1bc 62.20 Ϯ 8.54b Adult 0.90 Ϯ 0.06a 113.98 Ϯ 1.30a 17.6 Ϯ 1.5c 90.80 Ϯ 7.18c Third instar Egg 0.74 Ϯ 0.09a 104.07 Ϯ 5.72a 21.6 Ϯ 5.9a 27.37 Ϯ 3.57a Larva 0.87 Ϯ 0.05a 109.87 Ϯ 3.65a 26.4 Ϯ 4.8a 26.36 Ϯ 2.95a Nymph 0.96 Ϯ 0.01a 114.27 Ϯ 2.79a 36.0 Ϯ 3.1a 40.87 Ϯ 3.68b Adult 0.97 Ϯ 0.01a 112.52 Ϯ 1.93a 23.8 Ϯ 3.6a 58.50 Ϯ 3.87c

61.36 Ϯ 9.68 min; second: 113.98 Ϯ 1.30 min; t ϭ 2.43 density, the only signiÞcant differences in prey con- and 2.89; P ϭ 0.04 and 0.02; df ϭ 4, for Þrst and second sumption among mite life stages were found in second instars, respectively). instar predators (Table 3). Among M. basalis larval Handling Time. In all three M. basalis instars, han- stages, Þrst instars consumed signiÞcantly fewer of dling times of both T. kanzawai and P. citri increased each prey life stage at low density than did second or with advancing age/stage of prey (Tables 1Ð3). For third instars (H ϭ 9.12, F ϭ 14.82, 16.05, 15.32; df ϭ 14; example, third-instar M. basalis consumed a T. kanza- P ϭ 0.01, 0.001, 0.0004, 0.0005, respectively, for mite wai egg in Ϸ7 s and an adult in Ϸ60 s compared with egg, larva, nymph, and adult), whereas there were no an average of 9 and 30 s, respectively, for P. citri. On signiÞcant differences in prey consumption between both mite species, the handling times for M. basalis second and third instars. generally decreased with advancing lacewing stage. Handling times were shortest for M. basalis third in- Discussion stars and longest for Þrst instars (Tables 1Ð3). Mallada basalis took a shorter time to handle P. citri Many species of green lacewings are generalist than to handle T. kanzawai except for prey eggs (cf. predators, preying on small soft-bodied arthropods. Tables 1 and 2), where the mean handling time was However, not all species in this range are accepted as signiÞcantly longer for P. citri than for T. kanzawai prey or at least not equally so (Principi and Canard (Þrst instar: t ϭϪ4.11; df ϭ 4; P ϭ 0.0147; second instar: 1984). With respect to M. basalis, our results indicated t ϭϪ4.93; df ϭ 4; P ϭ 0.0079; third instar: t ϭ 3.96; df ϭ that both T. kanzawai and P. citri were moderately to 4; P ϭ 0.0167). With respect to P. citri density, handling highly acceptable to all three larval instars of the times in most cases were consistently shorter for M. predator. This range of acceptability covered all life basalis at the higher P. citri density than at the lower stages of both papaya mite species, which is a positive one (cf. Tables 2 and 3). The greatest statistical dif- indicator for augmentative biological control because ferences were observed for third-instar predators. effective biological control agents should be able to Short-Term Consumption Rate. In 2-h no-choice control the early life stages of a pest (Royama 1981, tests, consumption of T. kanzawai by M. basalis in- Bellows et al. 1992). Additionally, M. basalis had a creased signiÞcantly with predator life stage (P Ͻ similar degree of prey acceptability to both mite spe- 0.0001). Third instars consumed Ϸ68 T. kanzawai cies at densities typically found in the Þeld. Because T. adults and Ϸ311 eggs, second instars consumed kanzawai and P. citri can occur simultaneously on Ϸ26 adults and Ϸ136 eggs, and Þrst instars con- papaya, including co-infestation of the same leaves, sumed Ϸ4 adults and Ϸ20 eggs (Table 1). There was our results suggest that predation rates may be similar a trend for decreased consumption by M. basalis as regardless of the species or life stage of mite prey prey life stage increased. Results were signiÞcantly encountered. different between mite immature and adult stages A comparison among M. basalis larval instars (P Ͻ 0.05; Table 1). showed that third instars accepted T. kanzawai adults A similar trend for increased prey consumption with to a greater extent than did Þrst or second instars. In advancing predator larval instar was observed when some predators, having a sufÞciently large body size M. basalis fed on P. citri at high density (Table 2). In relative to the size of the prey is important for suc- 2-h no-choice trials, third-instar lacewing consumed cessful predation and, hence, may affect relative ac- Ϸ114 P. citri adults and Ϸ303 eggs, whereas Þrst instars ceptability (Molles and Pietruszka 1987, Sabelis 1992, consumed Ϸ12 adults and Ϸ83 eggs, respectively. As Dean and Schuster 1995). In part, size differences with T. kanzawai, consumption of P. citri by M. basalis between prey and predator may contribute to prey decreased with advancing prey life stage (Table 2). defense (Pastorok 1981). Our observations suggest However, there was a different trend between the two that the lower acceptability of T. kanzawai adults by mite species: M. basalis consumed statistically similar Þrst- and second-instar M. basalis may be attributed to amounts of T. kanzawai eggs, larvae, and nymphs, and the greater mobility of adult mites, which makes it signiÞcantly fewer adults (Table 1), whereas statistical easier to evade capture. differences in prey consumption were found for all Most insects spend only a small part of their time immature stages of P. citri but not between nymphs feeding compared with resting and other activities and adults (Table 2). In general, all larval instars of M. (Matthews and Matthews 1978, Cohen 1985, Wieden- basalis consumed more P. citri than T. kanzawai. How- mann and OÕNeil 1991). Our study indicated that, ever, differences in consumption between mite spe- during a 2-h period after an absence of prey, second- cies were consistently statistically signiÞcant only for and third-instar M. basalis foraged for most of the time adult prey (Þrst instar: t ϭ 3.55, df ϭ 4, P ϭ 0.008; on all life stages of T. kanzawai and P. citri, whereas second instar: t ϭ 3.55, df ϭ 4, P ϭ 0.007; third instar: Þrst instars spent only half of the time actively forag- t ϭ 2.93, df ϭ 4, P ϭ 0.02, respectively). ing. One possible explanation for reduced foraging in Consumption was also inßuenced by prey density. Þrst instars is that they require less food to become All instars of M. basalis consumed fewer prey when P. satiated than later instars. citri was offered at low density than at high density Foraging time generally did not differ between the (P Ͻ 0.05; cf. Tables 2 and 3). Furthermore, whereas two mite species or between high and low population numbers of P. citri consumed differed among life densities of P. citri. The long period of foraging on both stages at the higher prey density (Table 2), at the low pest mites increases the potential effectiveness of M. 720 ENVIRONMENTAL ENTOMOLOGY Vol. 38, no. 3 basalis as a biological control agent. However, Þrst- from the available data should be considered as ten- instar lacewings spent a signiÞcantly greater propor- tative until future studies that record covariates, such tion of time foraging for T. kanzawai nymphs and as size of consumed prey, are carried out. adults compared with eggs or larvae. The longer ac- Our study also showed that lacewing handling times tivity periods on mite nymphs and adults may be were shorter when P. citri were offered at the higher linked to longer handling times needed or lower for- density than at the lower one. Handling time is a aging efÞciency for these later life stages. In fact, general component of a predatorÕs behavior and has an handling times were longer on mite nymphs and adults important effect on the functional response through than on eggs and larvae despite the fact that the latter its inßuence on prey attack rate (Holling 1959). Pred- were fully consumed by Þrst-instar M. basalis, whereas ators may increase search and handling efÞciency nymphs and adults were often partially eaten. Inter- through learning as prey density increases (Holling estingly, there were no signiÞcant differences in pred- 1959). In addition, handling times may be longer at ator foraging time among life stages of P. citri, although lower densities because they may spend more time adult prey often were only partially consumed. In with individual prey to extract as much of the available addition, Þrst- and second-instar M. basalis foraged nutrients as possible. The shorter handling time of M. signiÞcantly longer on P. citri eggs compared with T. basalis in response to increased P. citri density could kanzawai eggs even though the eggs of both mite increase the level of biological control of mite popu- species are similar in size (Ϸ0.13Ð0.15 mm in diame- lations in the Þeld. However, previous theoretical and ter). Although untested, these results may reßect dif- empirical studies indicate that the type III functional ferences in physical (e.g., chorion thickness or surface response, in which attack rates increase proportionally structure) or chemical (e.g., defensive compounds) with prey density, represents the only response with properties or nutritional quality among various life population regulating possibilities (Holling 1965, Huf- stages of different mite species, which, indirectly, may faker et al. 1971, Gotelli 1995). Research on green have affected foraging time (see Hassell and South- lacewing species has shown that they exhibit a type II wood 1978, Lance et al. 1986, Slansky and Wheeler functional response (Nordlund and Morrison 1990, 1989). Stewart et al. 2002). Nevertheless, the type of func- We observed high prey consumption rates by larval tional response that M. basalis exhibits on citrus and instars of M. basalis. In fact, relative to phytoseiid Kanzawa mites needs to be examined. mites, which currently are the most widely used pred- Collectively, this study showed that a domesticated ators for biological control of teteranychid mites, our line of M. basalis possesses high prey acceptability of studies showed that even Þrst-instar M. basalis have a two papaya pest mites of all life stages and has rela- higher consumption rate. For example, Þrst-instar tively short handling times and high prey consumption lacewings consumed an average of 20 tetranychid eggs rates. Because M. basalis can be mass produced on in only 2 h compared with Ͻ15 eggs for various phyto- artiÞcial diet in a cost-effective manner (Chang 2000, seiid predators during their entire nymphal period Lee 2003) and has also been shown to be less expen- (Zhang 2003). In addition, the tendency for M. basalis sive than pesticides for controlling Tetranychus mites to increase predation with increasing prey density on strawberries (Chang and Huang 1995), M. basalis may enable it to control the mites at high population may be promising even as a biopesticide used for densities. We also found that total consumption was inundative release to control papaya pest mites in higher on P. citri than on T. kanzawai, and the differ- screenhouses. However, development of a protocol ence was especially signiÞcant for adult mites. These for releasing M. basalis under Þeld conditions will differences may be caused by differences in biomass depend on additional data, including assessing prey or in nutritional content, and it could affect control preference and other foraging behavior and predatorÐ efÞcacy of M. basalis on these two pest mites. prey ratios that are effective in papaya screenhouses. Handling time is an important factor inßuencing the amount of prey consumed (Rogers 1972). In general, M. basalis has short handling times. For example, third Acknowledgments instars consume a Kanzawa mite adult within 1 min, We thank P. I. Nelson for assistance in statistical analyses; which is much shorter than those recorded (Ϸ4Ð200 S. L. Liu and G. Y. Liu for maintaining the insects, mites, and min) for predatory mites feeding on phytophagous plants in the laboratory; and R. F. Hou, J. Lord, W. J. Wu, and mites (Zhang et al. 2000, Cote 2001). Our results also two anonymous reviewers for critically reviewing the manu- showed that handling times of both mite species in- script. Voucher specimens (2008-1-1) were deposited in the creased with prey life stage and decreased with pred- Insect and Mite Museum, Division of Applied Zoology, Tai- wan Agricultural Research Institute. This is Contribution ator life stage. This corresponds with other studies in 09-005-J of the Kansas Agricultural Experiment Station, Kan- which handling times were relative to predatorÐprey sas State University, Manhattan, KS. This study was sup- size (Cook and Cockrell 1978, Mills 1982, Cohen and ported by research grants from Council of Agriculture, Ex- Tang 1997). However, comparisons of within and ecutive Yuan, Taiwan. among predator variances indicated that it is difÞcult to justify treating these responses as random samples from normal distributions. This problem cannot be References Cited Þxed by transforming the data or using nonparametric Anonymous. 2006. Agricultural statistics yearbook. Council analyses. Therefore, assessing statistical signiÞcance of Agriculture, Taipei, Taiwan. June 2009 CHENG ET AL.: PREDATION OF M. basalis ON PAPAYA PEST MITES 721

Bellows, T. S., R. G. Van Driesche, Jr., and J. S. Elkington. Lance, D. R., J. S. Elkington, and C. P. Schwalbe. 1986. 1992. Life-table construction and analysis in the eval- Feeding rhythms of gypsy moth larvae: effect of food uation of natural enemies. Annu. Rev. Entomol. 37: quality during outbreaks. Ecology 67: 1650Ð1654. 587Ð614. Lee, W. T. 1994. Technical development of microencapsu- Chang, C. P. 2000. Investigation on the life history of Mal- lated artiÞcial diets for Mallada basalis Walker. Chin. J. lada basalis (Walker) (Neuroptera: Chrysopidae) and Entomol. 14: 47Ð52. the effects of temperatures on its development. Chinese Lee, W. T. 1995. Technical improvement for group-rearing J. Entomol 20: 73Ð87. larvae Mallada basalis (Walker) (Neuroptera: Chrysopi- Chang, C. P., and S. C. Huang. 1995. Evaluation of the ef- dae). Chin. J. Entomol. 15: 11Ð17. fectiveness of releasing green lacewing, Mallada basalis Lee, W. T. 2003. Successive group-rearing of Mallada basa- (Walker) for the control of tetranychid mites on straw- lis with microcapsulated artiÞcial diet and cost analysis. berry. Plant Prot. Bull. 37: 41Ð58. Plant Prot. Bull. 45: 45Ð52. Cheng, C. H. 1966. Observations on the ecology of citrus Lin, C. C., H. J. Su, and D. N. Wang. 1989. The control of red mite (Panonychus citri (McGregor)) in Taiwan. papaya ringspot virus in Taiwan, R.O.C. ASPAC Tech. Plant Prot. Bull 8: 80Ð89. Bull. 114: 1Ð13. Cohen, A. C. 1985. Metabolic rates of two hemipteran mem- Lo, K. C. 1997. Use of predators and prospect of controlling bers of a predator-prey complex. Comp. Biochem. agricultural pests in Taiwan. Chin. J. Entomol. Spec. Publ. Physiol. 81A: 833Ð836. 10: 57Ð65. Cohen, A. C., and R. Tang. 1997. Relative prey weight in- Lo, K. C. 2002. Biological control of insect and mite pests on ßuences handling time and biomass extraction in Sinea crops in TaiwanÑa review and prospection. Formosan confusa and Zelus renardii (Heteroptera: Reduviidae). Entomol. Spec. Publ. 3: 1Ð25. Environ. Entomol. 26: 559Ð565. Lu, C. T., and C. L. Wang. 2006. Control effect of Mallada Cook, R. M., and B. J. Cockrell. 1978. Predator ingestion rate basalis on insect pests of nethouse sweet peppers. J. and its bearing on feeding time and the theory of optimal Taiwan Agric. Res. 55: 111Ð120. diets. J. Anim. Ecol. 47: 529Ð547. Matthews, R. W., and J. R. Matthews. 1978. Insect behavior. Cote, K. W. 2001. Using selected acaricides to manipulate Wiley, New York. Tetranychus urticae Koch populations in order to enhance Mills, N. J. 1982. Satiation and the functional response: a test biological control provided by phytoseiid mites. MS the- of a new model. Ecol. Entomol. 7: 305Ð315. sis, Virginia Tech, Blacksburg, VA. Molles, M. C., and R. D. Pietruszka. 1987. Prey selection by a stoneßy: the inßuence of hunger and prey size. Oeco- Cranham, J. E., and W. Helle. 1985. Pesticide resistance in logia (Berl.) 72: 473Ð478. the Tetranychidae, pp. 405Ð421. In H. Helle and M. W. Nordlund, D. A., and R. K. Morrison. 1990. Handling time, Sabelis (eds.), World crop pests 1B. Spider mites: their prey preference and functional response for Chrysoperla biology, natural enemies and control. Elsevier, Amster- ruﬁlabris in the laboratory. Entomol. Exp. Appl. 57: 237Ð dam, The Netherlands. 242. Dean, D. E., and D. J. Schuster. 1995. Bemisia argentifolii Pastorok, R. A. 1981. Prey vulnerability and size selection by (Homoptera: Aleyrodidae) and Macrosiphum euphorbiae Chaoborus larvae. Ecology 62: 1311Ð1324. (Homoptera: Aphididae) as prey for two species of Chry- Principi, M. M., and M. Canard. 1984. Feeding habits, pp. sopidae. Environ. Entomol. 24: 1562Ð1568. 76Ð92. In M. Canard, Y. Se´me´ria, and T. R. New (eds.), Goka, K. 1998. Mode of inheritance of resistance to three Biology of Chrysopidae. Dr W. Junk Publishers, The new acaricides in the Kanzawa spider mite Tetranychus Hague, The Netherlands. kanzawai Kishida (Acari:Tetranychidae). Exp. Appl. Ac- Purcifull, D. E., J. R. Edwardson, E. Hebert, and D. Gon- arol. 22: 699Ð708. salves. 1984. Papaya ringspot virus. CMI/AAB descrip- Gotelli, N. J. 1995. A primer of ecology. Sinauer, Sunder- tions of plant viruses, No. 292. land, MA. Rogers, D. J. 1972. Random search and insect population Hao, H. H., H. L. Wang, W. T. Lee, and K. C. Lo. 1996. models. J. Anim. Ecol. 41: 369Ð383. Studies on biological control of spider mites on papaya. J. Royama, T. 1981. Evaluation of mortality factors in insect Agric. Res. China 45: 411Ð421. life table analysis. Ecol. Monogr. 51: 495Ð505. Hassell, M. P., and T.R.E. Southwood. 1978. Foraging strat- Sabelis, M. W. 1992. Predatory arthropods, pp. 225Ð264. In egies in insects. Annu. Rev. Ecol. Syst. 9: 75Ð98. M. J. Crawley (ed.), Natural enemies: the population Ho, C. C., K. C. Lo, and W. H. Chen. 1997. Spider mite biology of predators, parasites and diseases. Blackwell, (Acari: Tetranychidae) on various crops in Taiwan. J. Oxford, United Kingdom. Agric. Res. China 46: 333Ð346. Shi, M. S., J. X. Chen, and R. L. Deng. 1990. Structural Holling, C. S. 1959. The components of predation as re- cultivation of papaya. Taiwan Agric. 26: 101Ð106. vealed by a study of small mammal predation of the Slansky, F., Jr., and G. S. Wheeler. 1989. Compensatory in- European pine sawßy. Can. Entomol. 91: 293Ð320. creases in food consumption and utilization efÞciencies Holling, C. S. 1965. The functional response of predators to by velvetbean caterpillars mitigate impact of diluted diets prey density and its role in mimicry and population reg- on growth. Entomol. Exp. Appl. 51: 175Ð187. ulation. Mem. Entomol. Soc. Can. 45: 1Ð60. StatPoint. 2005. Statgraphics Centurion XV. StatPoint, Huang, C. C., J. G. Tasy, and M. F. Cheng. 1997. Preliminary Herndon, VA. survey on the diseases and insect pests of Camellia sinensis Stewart, C. D., S. K. Braman, and A. F. Pendley. 2002. Func- L. Kuntze in Chiayi highland district. Agricultural Exten- tional response of the Azalea plant bug (Heteroptera: Miri- sion Committee, Taiwan National Chiayi Institute of dae) and a green lacewing Chrysoperla ruﬁlabris (Neurop- Technology, Chiayi, Taiwan. tera: Chrysopidae), two predators of the Azalea lace bug Huffaker, C. B., P. S. Messenger, and P. DeBach. 1971. The (Heteroptera: Tingidae). Environ. Entomol. 31: 1184Ð1190. natural enemy component in natural control and the Tzeng, C. C., and S. S. Kao. 1996. Evaluation on the safety of theory of biological control, pp. 16Ð67. In C. B. Huffaker pesticides to green lacewing, Mallada basalis larvae. Plant (ed.), Biological control. Plenum, New York. Prot. Bull. 38: 203Ð213. 722 ENVIRONMENTAL ENTOMOLOGY Vol. 38, no. 3

Wiedenmann, R. N., and R. J. O’Neil. 1991. Searching be- Yamamoto, A., H. Yoneda, R. Hatano, and M. Asada. 1996. havior and time budgets of the predator Podisus macu- Studies on hexythiazox resistance in phytophagous mites. liventris. Entomol. Exp. Appl. 60: 83Ð93. Stability of hexythiazox resistance in the citrus red mite, Wu, T. K. 1992. Feasibility of controlling citrus red spider Panonychus citri (McGregor) under laboratory and Þeld mite, Panonychus citri (Acarina: Tetranychidae) by green conditions. J. Pestic. Sci. 21: 37Ð42. lacewing, Mallada basalis (Neuroptera: Chrysopidae). Zhang, Y. X., Z. Q. Zhang, J. Z. Lin, and J. Ji. 2000. Potential Chin. J. Entomol. 12: 81Ð89. of Amblyseius cucumeris (Acari: Phytoseiidae) as a bio- Wu, T. K. 1995. Integrated control of Phyllocnistis citrella, control agent against Schizotetranychus nanjingensis Panonychus citri, and Phyllocoptruta oleivora with peri- (Acari: Tetranychidae) in Fujian, China. Syst. Appl. Ac- odic releases of Mallada basalis and pesticide applica- arol. Spec. Publ. 4: 109Ð124. tions. Chin. J. Entomol. 15: 113Ð123. Zhang, Z. Q. 2003. Mites of greenhouses: identiÞcation, bi- Yamada, K., and T. Tsutsumi. 1990. Injurious biology and ology and control. CABI Publishing, Wallingford, United control of Kanzawa spider mite, Tetranychus kanzawai Kingdom. Kisida, in Japanese persimmon. Proc. Assoc. Pl. Prot. Ky- ushu 36: 186Ð189. Received 18 August 2008; accepted 17 February 2009.