Lepidoptera: Lycaenidae) on Planococcus Citri (Risso) (Homoptera: Pseudococcidae)
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J Pest Sci DOI 10.1007/s10340-010-0303-8 ORIGINAL PAPER Development, life history characteristics and behaviour of mealybug predator, Spalgis epius (Westwood) (Lepidoptera: Lycaenidae) on Planococcus citri (Risso) (Homoptera: Pseudococcidae) Anegunda S. Dinesh • Melally G. Venkatesha • Sompalyam Ramakrishna Received: 1 November 2009 / Accepted: 1 April 2010 Ó Springer-Verlag 2010 Abstract The development of immature stages, life his- Introduction tory and behaviour of mealybug predator, Spalgis epius (Westwood) (Lepidoptera: Lycaenidae) reared on mealy- More than 99% of Lepidoptera survive solely on living bugs, Planococcus citri (Risso) (Homoptera: Pseudococ- plants (Pierce 1995). Among the aphytophagous Lepidop- cidae) was studied in the laboratory. Larvae of S. epius are tera, about 120 species in the subfamily Miletinae (Lepi- a potential predator of different species of mealybugs in doptera: Lycaenidae) feed on ant brood or Hemiptera India. The predator completed its life cycle in 23.8 days (Pierce 1995). Most of the aphytophagous butterflies are with four larval instars. Mean incubation period of egg was extremely rare, and several are endangered (Pierce 1995; 3.9 days. Mean duration of development of larval stages, Wynhoff et al. 1998). The genera Spalgis Moore, Tharaka prepupa and pupa was 9.4, 0.9 and 9.5 days, respectively. Doherty and Feniseca Grote of Miletinae feed on ant-ten- The first and last instar larvae measured 1.9 and 11.4 mm ded Hemiptera (including Homoptera). These hemipteran- in length, respectively. Length and width were not signif- feeders live among their prey without provoking an escape icantly correlated in larvae. Head capsule width was not response or an attack response from the ant mutualists of significantly correlated with larval length in any instar. The Hemiptera (Scudder 1899). Different species of mealybugs female-to-male sex ratio was 1.45:1. Adults were ready for (Homoptera: Pseudococcidae) are serious pests of wide mating one day after eclosion. The pairs remained in range of economically important crops such as coffee, copula on an average of 61.3 min. The gravid female citrus, guava, mango, mulberry, vegetables, ornamental contained 74.6 eggs in the ovaries. Unfed butterflies (both plants, etc., worldwide (Browning 1992). The apefly, males and females) lived 3–4 days, significantly shorter Spalgis epius (Lepidoptera: Lycaenidae: Miletinae) has than those with access to water (6–7 days). The results of been recorded as a predator of various species of mealy- this study will be useful to utilize the predator as a bio- bugs viz., Dactylopius sp. (Aitken 1894), Planococcus control agent. virgatus (Ckll.) (Misra 1920), P. lilacinus (Ckll.) (Ayyar 1929), P. citri (Risso) (Chacko et al. 1977), Ferrisia Keywords Development Á Life history Á Lepidoptera Á virgata (Ckll.) (Chacko and Bhat 1976) and Maconelli- Lycaenidae Á Mealybugs Á Predator Á Spalgis epius coccus hirsutus (Green) (Mani et al. 1987) in India. Fur- thermore, the larva of S. epius has been reported as a potential predator of P. citri in coffee plantations, and M. hirsutus in mulberry gardens in India (Gowda et al. 1996; Mani 1995; Rahiman and Vijayalakshmi 1998). P. citri and M. hirsutus are major pests of coffee and mulberry, respectively, in India (Le Pelley 1968; Thanga- Communicated by D.C. Weber. mani and Vivekanandan 1983). S. epius occurs in India, Burma and Sri Lanka (De Niceville 1890), Philippines and A. S. Dinesh Á M. G. Venkatesha (&) Á S. Ramakrishna Bangalore University, Bengaluru, India Java (Le Pelley 1943), Bangladesh (Ali 1978), and Thai- e-mail: [email protected] land (Lohman and Samarita 2009). S. epius inhabits 123 J Pest Sci agricultural and wooded areas and is not commonly seen in pupa, and adult were measured with a calibrated eyepiece the field due to its small size and drab colour (Venkatesha micrometer in a stereo zoom microscope. External mor- et al. 2004). De Niceville (1890) and Bingham (1907) have phologies of the egg, each larval instar, prepupa, pupa and described the morphology of S. epius adults. Venkatesha adult were also studied. et al. (2004) and Venkatesha (2005) have made preliminary observations on the behaviour of S. epius and its interaction Biology with ants in the field. Although S. epius is an important predator of mealybugs Observations on the eclosion timing, sex ratio, mating and in India, virtually no research has been conducted on its egg-laying behaviour of adults and the larval feeding habit development and biology. Moreover, no detailed life his- were recorded. The durations of the preoviposition and tory and biology of any hemipteran-feeding lycaenid but- oviposition periods were documented. Freshly eclosed terfly has been studied so far. The objective of this study female and male adults of uniform size and age were iso- was to determine the development of immature stages, life lated and kept in nylon cages (30 cm 9 30 cm 9 30 cm) history and behaviour of S. epius that was reared on P. citri singly, and the influence of nutrition on longevity was in the laboratory. studied by feeding the adults independently on three diets: 10% honey (diluted in water), ripe banana, and tap water. Adults without food or water were maintained as controls. Materials and methods The mortality of the adults fed on different diets including control was recorded at 24-h intervals. In order to deter- Field source and lab rearing of predator mine the potential fecundity, 2-day-old adult females were dissected, and the numbers of immature and mature eggs In order to rear S. epius in the laboratory, mealybug P. citri present in the ovaries were noted. was cultured on pumpkins (Cucurbita maxima Duchesne) following the method of Serrano and Lapointe (2002). The Data analysis mealybug-infested pumpkin was maintained in a nylon rearing cage (30 cm 9 30 cm 9 30 cm). A few S. epius The student t-test was employed to analyse the differences larvae were collected from the mealybug infested croton in body length and wingspan between the female and male plants (Codiaeum spp.) at the Bangalore University cam- butterflies. The differences in longevity of the fed females pus, Bengaluru, India (latitude 12°580N, longitude 77°350E, and males on different diets as well as control were ana- elevation 921 m). The field-collected larvae were reared on lysed utilizing one way ANOVA-Tukey HSD test (SPSS the mealybug-infested pumpkins in the laboratory. Adults Inc 2001). The growth of the larval length and width, and of S. epius emerged in the laboratory were allowed to mate the larval length and head capsule width were correlated. in an outdoor nylon mating cage (6 m width 9 6m length 9 10 m height) and provided with mealybug- infested pumpkins for egg deposition in the same cage. The Results eggs laid in the mass of mealybugs on the pumpkin were carefully separated and kept individually in Petri dishes Morphology (5 cm diameter). Newly emerged larvae from these eggs were maintained in the same Petri dishes and provided with Egg: Colour greenish-blue when laid, changing to whitish egg masses and nymphs of mealybugs as food until they before hatching. Egg disk-shaped, sculptured, and both the reached prepupal stage. The predator was reared under the top and bottom flattened with micropylar depression in the variable mean maximum temperature 29.0 ± 1.8°C, mean top (Fig. 1a). Egg 0.48 ± 0.05 mm in diameter. minimum temperature 26.5 ± 1.4°C, and mean relative Larva: It moulted three times, and there were four larval humidity 44.4 ± 6.7% RH. instars. The length and width, and the head capsule width of four larval instars are given in Table 1. Life cycle and morphology First instar larva: Body pale white with dark brown head, fringed with fine white setae (Fig. 1b). The moulting of the larvae was confirmed by examining Second instar larva: Head dark brown. Body grey with the Petri dishes daily for exuviae and head capsules. The white mid-dorsal line and slightly covered with white wax egg, larval, prepupal and pupal developmental period, and coating, broken at each segment, and slug like. Setae more number of instars in a life cycle were recorded. The egg, prominent and interwoven with eggs of mealybugs each larval instar, head capsule of each instar, prepupa, (Fig. 1c). 123 J Pest Sci Fig. 1 Spalgis epius a Egg; b I instar larva; c II instar larva; d III instar larva; e IV instar larva; f prepupa; g pupa; h female, dorsal side; i male, dorsal side; j female, ventral side; k male, ventral side; l larvae feeding on mealybugs and m adults in copula Table 1 Measurements (mm) of the larva, prepupa, pupa and head capsule of Spalgis epius Stages n Length Width Head capsule width Mean ± SD Range Mean ± SD Range Mean ± SD Range Larva I instar 20 1.9 ± 0.1 1.8–2.2 0.6 ± 0.08 0.5–0.8 0.23 ± 0.04 0.2–0.3 II instar 20 3.4 ± 0.1 3.2–3.8 1.7 ± 0.1 1.5–1.9 0.43 ± 0.04 0.4–0.5 III instar 20 6.6 ± 0.5 5.8–7.2 3.8 ± 0.2 3.4–4.2 0.82 ± 0.04 0.8–0.9 IV instar 20 11.4 ± 0.5 10.5–12.1 6.6 ± 0.4 5.6–7.1 1.03 ± 0.04 1.0–1.1 Prepupa 20 7.9 ± 0.6 7.0–9.0 4.1 ± 0.2 4.0–4.5 – – Pupa 20 6.9 ± 0.3 6.5–7.5 3.9 ± 0.2 3.9–4.2 – – Third instar larva: Similar to second instar but with Pupa: Light brown on the dorso-lateral side and whitish brown mid-dorsal line and covered with thick wax coating grey on the ventral side.