1027 Vol.53, n. 5: pp.1027-1035, September-October 2010 BRAZILIAN ARCHIVES OF ISSN 1516-8913 Printed in Brazil BIOLOGY AND TECHNOLOGY AN INTERNATIONAL JOURNAL Food Extraction by the Males of Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae) from Cotton Leafworm Larvae Alexandre Igor de Azevedo Pereira 1, Francisco de Sousa Ramalho 1*, Karjoene Cassimiro Vilar Rodrigues 1, José Bruno Malaquias 1, Jefferson Virgínio da Silva Souza 1 and José Cola 2 Zanuncio 1Embrapa Algodão; Unidade de Controle Biológico; C.P. 174; 58107-720; Campina Grande - PB – Brasil. 2Universidade Federal de Viçosa; Departamento de Biologia Animal; Viçosa - MG - Brasil ABSTRACT In this work, the effect of different densities (1, 3, 5, 7 and 9) of 3rd instar Alabama argillacea (Huebner) larvae on food consumption by Podisus nigrispinus (Dallas) males was evaluated . The densities established were converted to weight of prey offered: 13.4 mg (one larva), 33.3 mg (three larvae), 54.3 mg (five larvae), 81.8 mg (seven larvae), and 110.34 mg (nine larvae). The quantity of food consumed by P. nigrispinus increased with the prey density. The density of preys did not affect the time spent by the predator to ingest the food. The quantity of food extracted per minute was always higher in smaller densities and lower in higher densities. Males mean body weight did not differ statistically between the treatments tested, and weight gain was smaller in the first two densities tested. Relative consumption rates increased with the quantity of larvae offered. P. nigrispinus males might change its predatory behavior as a function of the quantity of prey available. Key words: Cotton leafworm, predator, stinkbug, food consumption, nutrition INTRODUCTION Asopinae) are still neglected in agricultural practices, because the only species of this group in Cotton leafworm, Alabama argillacea (Huebner) commercial use for biological pest control in (Lepidoptera: Noctuidae) is the main cotton leaf North America and Europe is Podisus pest in Brazil (Bleicher, 1993; Ramalho, 1994; maculiventris (Say) (De Clercq, 2000). However, Silva et al., 1997), which is usually controlled by these predators have a promising future in the the pesticide (Malaquias et al., 2009), being their control of agricultural and forest pests of larvae the main biological target (Ramalho, 1994). economical importance. Among these species are One of the promising alternatives to reduce the use P. maculiventris and Perillus bioculatus of chemicals in the agricultural ecosystems is the (Fabricius) in North America and Europe, and integration between the natural enemies (predators Podisus nigrispinus (Dallas) in South America and parasitoids) and selective pesticides (Pereira et (Medeiros et al., 2004). Podisus nigrispinus is one al., 2005). of the most common species of Asopinae studied Predaceous stinkbugs (Hemiptera: Pentatomidae, in the Neotropical region (De Clercq, 2000), and * Author for correspondence: [email protected] Braz. Arch. Biol. Technol. v.53 n. 5: pp. 1027-1035, Sept/Oct 2010 1028 Pereira, A. I. A. et al. has been reported in several countries of South and The specimens of predator P. nigrispinus and its Central America (Thomas, 1992; Medeiros et al., prey A. argillacea were kept in environmental 2004; Lemos et al., 2005) as an important chambers at constant temperature of 26 + 1ºC, RH biological control agent in different crops. of 60 + 10%, and a photoperiod of 12:12 (L:D) h. Although P. nigrispinus is one of the most studied Fifth instar nymphs of P. nigrispinus with forty- species, there is still little information on its eight-hour-old were removed from the rearing feeding behavior when submitted to different cage and transferred to transparent plastic cups quantities of prey. Food consumption and its (500 mL), with 10 nymphs per cup in utilization are basic needs for the growth, environmental chambers. A 2.5 mL plastic tube development, and reproduction of all organisms. with distilled water was inserted through each cup The energy obtained is either compromised or lid to keep the moisture inside the cups. A total of already destined to the maintenance of certain 130 nymphs from the 5th instar of the predator metabolic processes, when the source of food were used. Each nymph received as diet two 3rd becomes scarce or nutritionally poor (Legaspi and instar cotton leafworm larvae offered daily per Legaspi, 1998). The feeding regime may change cup. The quantification of newly emerged adults the life cycle of predaceous pentatomids, as well- was made every 24 h. After the emergence, virgin fed individuals reproduce better and more adult males were individualized in 100 mL plastic frequently (Engelmann, 1970; Lenski, 1984; cups with 2.5 ml plastic tubes inserted through Lemos et al., 2001). The quantity of ingested food their lids for water supply and moisture. All the certainly depends on the predator’s ability in adult males used in the experiment remained 24 h detecting, capturing, and killing their preys. These without food after individualization, and then skills reflect the differences in response of several weighed on an analytical scale (± 0.1 mg) “Mettler species of predators and their preys (Holling, H31AR”. 1961). Thus each predator can have different types A randomized complete-block design was used in of behavior in relation to the density of preys. The the study, with five treatments: (1) one larva of A. number of individuals attacked by a predator in a argillacea (mean weight = 13.40 mg); (2) three certain density of preys depends on the success of larvae of A. argillacea (mean weight = 33.30 mg); the attacks, the time in which the prey is exposed (3) five larvae of A. argillacea (mean weight = to the predator, and the handling time of each prey 54.30 mg); (4) seven larvae of A. argillacea (mean (Holling, 1966). weight = 81.80 mg), and (5) nine larvae of A. Studies discussing the existing relation between argillacea (mean weight = 110.34 mg), distributed the number of preys captured by the predators in four replications; each experimental unit compared to the density of preys, known as comprised of five P. nigrispinus males functional response (Holling, 1966; Mills, 1982), individually in 100 mL plastic cups. The first are important for a better understanding of the assessments were carried out every 15 minutes relation between the predator and prey. The during the first 12 h, to estimate the ingestion time behavior of predators of the genus Podisus in quantified from the time the predator inserted part relation to their preys have been studied by of its mouth apparatus into the prey’s body, Tostowaryk (1972) and Hokyo and Kawauchi paralyzing the prey until the predator’s mouth (1975); however, little is known about the withdrawal from the prey’s body. The other predatory behavior of P. nigrispinus when assessments were carried out every 24 h, which submitted to different densities of prey. consisted of quantifying the number of totally In light of the importance of P. nigrispinus , it is larvae preyed (only the exoskeleton remained), surprising how little attention has been paid to partially preyed larvae (exoskeleton and part of predatory capacity of P. nigrispinus and its impact hemolymph was left), remaining larvae (living on cotton leafworm in Brazil. Therefore, this work larvae that escaped from preying), and the weight studied of effect of prey density, A. argillacea of larvae exposed to the predator on a daily basis. larvae on food extraction by P. nigrispinus male The larvae preyed were identified by features, predators in the laboratory. such as deformations and discoloration, according to O’Neil (1989). The quantity of larvae consumed by predator (Na) MATERIALS AND METHODS and the quantity of food extracted by the predator per prey (Fe) were estimated with the data Braz. Arch. Biol. Technol. v.53 n. 5: pp. 1027-1035, Sept/Oct 2010 Food Extraction by the Males of Podisus nigrispinus (Dallas) 1029 registered. From the quantity of food extracted by food offer increased. Predators are more likely to the predator per prey (Fe), what was left from each find their prey more frequently in higher densities prey after ingestion (Rf) was estimated through the of prey than in lower densities, which stimulates formula Rf = P – Fe (Holling, 1966), where P was greater efforts in attack, and thus neglects the the weight of each prey. The gain of weight per hunger effect in preying (Holling, 1966). predator was estimated through the difference A reduction in the quantity of food extracted by P. between the predator’s weight at the beginning and nigrispinus male from each attacked larva was at the end of nine days. Relative consumption rate detected as the quantity of prey offered increased (RCR) was also estimated through the formula (F= 16.38; P= 0.05), with this relationship TCR = Na/Pm.T (Waldbauer, 1968), where Pm described by a cubic function (F= 16.12; P= 0.05; was the mean predator weight gain in 24 h (T). R2= 0.99 (Fig. 2). The stabilization of the quantity The quantity of food extracted by minute (Fe min ) of food extracted from each prey (33.3 mg of prey were estimated from the quantity of food extracted available) (Table 1) could be possibly related to per prey (Fe) by the formula Fe min = Fe/Ti the quantity of food required by the predator to (mg.min -1) (Cohen, 1990), where Ti was the time remain or become satiated. According to Pereira et taken by the predator to extract the food. al. (2008), the quantity of food consumed and The data were submitted to variance analysis (SAS extracted by P. nigrispinus females from each Institute, 2006), and the means were compared by larva of A. argillacea decreased as the food Student-Newman-Keuls test ( P=0.05).