Uji Pemangsaan dan Tanggap Fungsional Predator Chysoperla carnea Stephens (Neuroptera: Crysopidae) Terhadap Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae)

Predation and Functional Response Test of Predator Chysoperla carnea Stephens (Neuroptera: Crysopidae) Against Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae). This study aims to evaluate the predatory capacity of C. carnea by measuring the rate of searching capacity and handling-time of one prey and its functional response to the population density of P. manihoti. The research was conducted at the Integrated Pest Management Laboratory (IPMLab), Faculty of Agriculture, Udayana University. The study was conducted from February to May 2019. Testing of functional responses used a randomized block design with 5 treatments (3, 6, 9, 12, 15 nymphs-3) each of which was repeated 10 times. The results showed that the prey searching-capacity when the population was low (3 nymphs-3) took longer (10.37 minutes), while when the population was high it took a short time (6.23 minutes). The length of time for handling one prey in the low population was 6.08 minutes, while in the high population it was 5.48 minutes. Predator C. carnea has a tpe-2 functional response to an increase in the population of P. manihoti nymphs with the equation Y = 4.32x / 1 + 1.973x (R2 = 0.980). The rate of predation increases sharply when the population of low increases, and decreases when the increase of prey population increases. C. carnea has the potential to be developed as a control agent for P. manihoti.

Mechanisms and fluid dynamics of foraging in heterotrophic nanoflagellates

ABSTRACTHeterotrophic nanoflagellates are the main consumers of bacteria and picophytoplankton in the ocean. In their micro-scale world, viscosity impedes predator-prey contact, and the mechanisms that allow flagellates to daily clear a volume of water for prey corresponding to 106 times their own volume is unclear. It is also unclear what limits observed maximum ingestion rates of about 104 bacterial prey per day. We used high-speed video-microscopy to describe feeding flows, flagellum kinematics, and prey searching, capture, and handling in four species with different foraging strategies. In three species, prey-handling times limit ingestion rates and account well for their reported maximum values. Similarly, observed feeding flows match reported clearance rates. Simple point-force models allowed us to estimate the forces required to generate the feeding flows, between 4-13 pN, and consistent with the force produced by the hairy (hispid) flagellum, as estimated using resistive force theory. Hispid flagella can produce a force that is much higher than the force produced by a naked flagellum with similar kinematics, and the hairy flagellum is therefore key to foraging in most nanoflagellates. Our findings provide a mechanistic underpinning of observed functional responses of prey ingestion rates in nanoflagellates.

Quantification of the abundance and diversity of predatory spiders in rice ecosystem of Rajendranagar, Telangana, India

The effective prey searching ability and polyphagy of spiders makes them important predators of crop pests. 19 species of spiders have been recorded in rice ecosystem (Rajeswaran et al., 2005). There is now a growing need to conserve all species and not only the large vertebrates (Samways, 1990) and contribute to the natural biological process. However, literature pertaining to their abundance and diversity in rice crop in Rajendranagar area is scant. Hence, the p resent study was conducted to understand their abundance and diversity. Spider samples were collected from rice fields of Rajendranagar in kharif and rabi seasons of 2011-12 and 2012-13. A total of 2,094 individuals collected in kharif represented eight families with a density of 12.48/sq.m. Members of Tetragnathidae were recorded most abundantly in kharif (46.32% of the Arachnid population) followed by Lycosids (26.22%). In rabi 1,095 spiders of seven families were collected with a density of 6.38/sq.m. Tetragnathidae andLycosidae were the most abundantly found species in rabi also comprising 27.85% and 26.12% of Arachnid population respectively. Study of guild composition was also carried out. A t-test between indices of richness, diversity, effective no.of species and species evenness of kharif and rabi seasons revealed that there were no significant differences with respect to these parameters (p>0.05) indicating that spider diversity of rice in Rajendranagar was more or less same between kharif and rabi seasons. This is the first study on the spider diversity of rice ecosystem of Rajendranagar, Hyderabad, India.

Prey sex pheromone as kairomone for a new group of predators (Coleoptera: Dasytidae,Aplocnemusspp.) of pine bast scales

During the last decades, an increasing number of predators were found to use specific prey pheromones as chemical cues. Beyond its ecological relevance, this knowledge has practical applications on insect conservation and pest control. In this study, we present first evidence that two species of the family Dasytidae (Coleoptera)Aplocnemus brevisRosenhauer andA. raymondiSainte-Claire Deville use the sex pheromone of the pine bast scaleMatsucoccus feytaudiDucasse (Hemiptera: Matsucoccidae) as kairomone to locate this prey. The feeding habits and biology ofAplocnemusspecies are practically unknown. In the laboratory, the adults ofAplocnemussp. acceptedM. feytaudiegg masses as food source as well as other diets. Females represented more than 90% ofAplocnemussp. attracted to the pheromone lures. We believe that females use this olfactory cue to locate suitable places for oviposition and that larvae are the predators ofMatsucoccus. This study further demonstrates that the response to the kairomone elicited short prey searching times, about 23% of the individuals appeared less than 12 min after lure exposure, being consistent with the hypothesis of prey specialization. Habitat and geographical distribution predict an ancestral association ofA. breviswithM. feytaudiand ofA. raymondiwithM. pini. Nevertheless, a recent prey shift ofA. raymondito the invasiveM. feytaudiin Corsica is in progress.