Foraging behavior of an aphidophagous female JBiopest 10(2):154-162 (2017) Diurnalhoverfly. foraging behavior of an aphidophagous hoverfly in an insectary plant patch Chandrima Emtia and Kazuro O hno* JBiopest 5(1): 1-6 ABSTRACT A series of foraging bouts of Episyrphus balteatus (DeGeer) females were observed and recorded throughout the day in phacelia (Phacelia tanacetifolia Bentham) patches. The dominant transitions of interplant movement, approaching and probing bouts were statistically more frequent in the morning than in the afternoon. In the morning, interplant movement of foragers was significantly longer and they were moving at higher places of phacelia patches. They approached and probed flowers considerably longer in morning compared to afternoon. A significant positive relationship between the number of open flowers in a patch and the patch residence time was observed in the morning. The proportion of females having swollen abdomen filled with phacelia pollen (68.2%) in the afternoon was significantly higher than that (31.82%) in the morning. In our study, E. balteatus females spent more time foraging in phacelia patches in morning compared to afternoon. Based on the results and by considering the dual resources requirements of a female hoverfly (flower foraging and searching for aphids to lay eggs), we will discuss the effective diurnal foraging of E. balteatus females in phacelia patches. Keywords: Conservation biological control (CBC), Episyrphus balteatus (DeGeer), Foraging behavior, Insectary plant, Phacelia tanacetifolia (Bentham). Citation: Chandrima Emtia and Kazuro Ohno. 2017. Diurnal foraging behavior of an aphidophagous hoverfly in an insectary plant patch. Journal of Biopesticides, 10 (2): 154-162. INTRODUCTION (Tenhumberg and Poehling, 1995). However, adult hoverflies require flower resources for Agricultural landscapes have been simplified their survival and reproduction (Hogg et al., at such a level that they no longer provide 2011; van Rijn et al., 2013; Van Rijn and natural enemies with appropriate resources in Wäckers, 2016). Several flowering plant time and space, resulting in the development species which are experimentally evaluated as of habitat management practices (Landis et al., insectary plants have great potential to 2000). One of the habitat management increase the adult hoverflies fitness. For practices is the provision of flower resources instance, phacelia (Phacelia tanacetifolia for enhancing conservation biological control Bentham) has been reported to enhance (CBC) of insect pests by predators and hoverfly, E. balteatus efficiency into parasitoids (e.g. White et al., 1995; Irvin et al., agricultural and horticultural systems as this 2006). For instance, aphidophagous hoverflies insectary plant increased its oviposition rate, larvae prey on aphids, while adults feed on lifetime fecundity and optimal reproductive flower resources such as pollen and nectar. potential (Laubertie et al., 2012). This Among the aphidophagous hoverflies, larvae insectary plant strips along winter wheat field of Episyrphus balteatus (DeGeer) (Diptera: margins were found to be effective in Syrphidae) has a great potential as a biocontrol enhancing E. balteatus population for agent of aphids (Chambers and Adams, 1986). controlling aphids (Hickman and Wratten, A single larva is able to feed on 660 to 1140 1996). Furthermore, Amorós-Jiménez et al. third-instar aphids during its development (2014) reported that the diet of adult hoverflies © 534 Emtia et al., influences performance of their larvae. 155 Moreover, aphidophagous females such as E. flowers. We planted this insectary plant in four balteatus need to select suitable colony such as plots of 3 x 2 m2 and one strip 1.0 x 10 m2 small and young colony consisting of nymphs from south to north edge of the field. Each of and or fundatrices as their oviposition sites for the plots and strip is termed as ‘patch’ in the the successful development of their offsprings present study. In the experimental field, (Kan, 1988). Therefore, the aphidophagous average temperature (°C) and relative female adults have to forage efficiently for humidity (%) were recorded to be 18.43 °C both flowers and aphids in a day. Hence and 70.5 % respectively by the thermo foraging decision such as allocating time recorder RTR-53 during the survey. budget for each of flower and aphid resources Foraging bouts in the phacelia patches is vital for the aphidophagous hoverflies. The We observed the foraging behavior of E. time budget allocation can be governed by balteatus females following the focal sampling different extrinsic (e.g. time of the day, with continuous recording method adopted predation, physical structure of the from Martin and Bateson (2007). We surveyed environment, microclimate) and intrinsic the phacelia patches from 7am to 5 pm on factors (e.g. physiology, sensory and central sunny days using voice recorder and stop nervous capacities) (Kramer, 2001). The few watch to observe the foraging behavior of each studies which have been carried out on individual as it entered the patch and hoverflies foraging for flower resources were continued until it left. The behavior was based on the interaction between some of divided into foraging bouts which may be extrinsic and intrinsic factors of foraging termed as a period of time spending in behavior (Gilbert, 1985; Cowgill et al., 1993a; performing each of the foraging activities. We Cowgill et al., 1993b; Sutherland et al., 1999; followed each individual during their Pontin et al., 2006; Yokoi and Fujisaki, 2009). residence in each of the patch. Whether any of However, to the best of our knowledge, the the observed E. balteatus female re-entered in diurnal foraging pattern of female any of the phacelia patch was not considered aphidophagous hoverflies in insectary flower in the present investigation as it is not possible patches linking their dual resource to distinguish between each individual. The requirements (flower foraging and searching foraging bouts observed in phacelia patches for aphids to lay eggs) has not been studied in were as follows: interplant movement detail. The aim of the present study is to (including hovering), approaching, probing, evaluate the diurnal foraging behavior pattern landing on the flower, landing on leaf, of female E. balteatus in phacelia (P. grooming and flying out. Brief description of tanacetifolia) plant patches. Based on the these bouts are presented here. Interplant results, diurnal foraging activities of E. movement (including hovering) is the flight of balteatus in phacelia (P. tanacetifolia) plant E. balteatus from one plant to another phacelia patches are illustrated and the diurnal foraging plant in the patches. This bout includes pattern of E. balteatus females is discussed hovering which is a slightly motioned flight. considering their dual resource requirement. The pattern of interplant movement height of foraging E. balteatus in phacelia patches was MATERIAL AND METHODS determined by measuring the heights of 10 Study site, hoverfly and insectary plant The study of foraging behavior of this hoverfly phacelia plants from the ground level in each was conducted in an experimental field of 10 x patch. The measured height was used as a N & reference to estimate pattern of interplant ׳ m2 at University of Miyazaki (36° 14 10 E) from April to May, 2014. During movement height of E. balteatus. Approaching׳ 40 ° 59 this period, the predominant hoverfly was is the flight (hover) around <4cm of phacelia E.balteatus. The foraging behavior study of plants. Sometimes, they were touching the this hoverfly species took place during the flower corolla. Probing is the feeding on blooming period of Phacelia (P. tanacetifolia) pollen and nectar from the flower after landing Foraging behavior of an aphidophagous female JBiopest 10(2):154-162 (2017) onhoverfly. the flower. We did not observe any nectar 156 feeding by the E. balteatus females in the E. balteatus becomes purple. Therefore, it was present study. These observation corroborate possible to use this purple colored abdomen as with the findings of White et al. (1995) in that an indicator of the abdomen condition of the theJBiopest deep corolla 5(1): 1of-6 phacelia limits the nectar foragers. The abdomen status of E. balteatus accessibility to hoverflies. So this insectary was investigated by visually checking their plant was used as pollen source for abdomen, while they were foraging on the enhancement of hoverflies in their study. In phacelia plants in the morning and in the our study, the probing by E. balteatus females afternoon. The abdomen of the observed is considered as the pollen feeding of phacelia hoverflies was termed as swollen if purple flowers. Landing on the flower is the landing colored pollen filled the abdomen and flat of E.balteatus on the flower without probing when almost no pollen was present. it. Landing on leaf is a stationary activity. Statistical analysis Grooming is cleaning mouthparts or antennae Tests for normality of each group were and fly out is leaving of the patch. conducted using the Kolmogorov-Smirnov We recorded the duration of each of the test. The statistically significant difference of foraging bout. The sequence of each foraging the proportion of instances of the dominant bout was used to construct standard-style transitions of main foraging bouts in the transition matrices. Such a sequence is then morning and the afternoon was evaluated by summarized in a two-way frequency matrix, Chi-square test. Where the normality with the preceding activities in the rows and assumption was not met, the non-parametric the following activities in the columns Mann-Whitney U-test was used to compare followed after Van Der Heijden et.al., 1990. the duration of interplant movement, For example, if we can assume that different approaching and probing between morning activities can be distinguished then a and afternoon. Interplant movement height of frequency fij denotes the number of times that the foragers were checked by Kruskal-Wallis category i is followed by category j. These test followed by Dunn’s test for multiple frequencies fij can be collected into a matrix F comparisons.