Latest Research on Parasitoid: Dec – 2019

Parasitoid Foraging and Learning

The diminutive size of most parasitoids undoubtedly has limited their choice as subjects for behavioral study, despite their great diversity in lifestyles and reproductive strategies. this chapter addresses their foraging behavior as influenced by learning. Most of their adult life female parasitoids look for host insects which, in turn, are under selection to avoid being found and devoured. This scenario sets the stage for the evolution of diverse hide-and-seek games played by parasitoids and their victims, most frequently herbivores. That parasitoids are successful in their go after hosts is evidenced by the vast number of parasitoid species and their importance in insect management. [1]

Offspring Sex Ratios in Parasitoid Wasps

Laboratory and field studies on about 100 species in sixteen families indicate that several factors can influence offspring sex ratios (males: females) in parasitoid wasps. for several species, the offspring sex ratio increases with one or more of the following: (1) maternal age at ovipositing or number of days since insemination; (2) the age of the father or the amount of times he has copulated; (3) extreme temperature; (4) decreasing host size, age, or quality; (5) female wasp density; and (6) the amount of progeny per host. Other factors which are shown to affect offspring sex ratios in some species include (1) number of hours since insemination; (2) genetic factors; (3) maternal size; (4) maternal die; (5) polyembryony; (6) photoperiod and relative humidity; (7) hos sex; and (8) host density. These factors may affect offspring sex ratios through females manipulating fertilization of their eggs or through other mechanisms, like differential mortality or changes in sperm availability. [2]

Immunological Basis for Compatibility in Parasitoid-Host Relationships

The insect system is a key defense against attack by parasitoids. Incompatible hosts often eliminate parasitoids by encapsulation, a process during which hemocytes form a multilayered envelope round the invading organism. Capsule formation involves cooperation between one or more classes of hemocytes and is probably going mediated by cytokines and adhesion molecules. Reciprocally, parasitoids have evolved a spread of strategies for overcoming host immune responses. Some parasitoids passively avoid elimination by developing in locations inaccessible to host hemocytes or by possessing surface features that fail to elicit an immune reaction. Other species actively disrupt the host system by injecting specific factors into the host at oviposition. especially, polydnaviruses related to several taxa of parasitoids disrupt capsule formation by killing hemocytes or altering their ability to stick to foreign surfaces. [3]

Host density and parasitoid presence interact and shape the outcome of a tritrophic interaction on seeds of wild lima bean

The interaction between the seed weevil Zabrotes subfasciatus and its parasitoid Stenocorse bruchivora, was investigated on seeds of two populations of untamed lima bean, sieva bean. By manipulating the amount of beetle larvae per seed and therefore the presence of parasitoids, we determined how factors associated with beetle larvae density, the seed during which they feed and therefore the parasitoid, may interact and affect host and parasitoid survival. Results showed that a rise in larval beetle density had a negative impact on beetle performance. This effect cascaded up to parasitoids, high larval density strongly reduced parasitoid emergence. Also, parasitoid presence resulted in faster beetle development and lower female weight. [4]

Functional Response of Two Egg Parasitoids of Trichogramma (Hymenoptera: Trichogrammatidae) Genre on Duponchelia fovealis Zeller (Lepidoptera: Crambidae) Eggs

Aims: to guage the potential of the parasitoids of the genus Trichogramma on European pepper moth, a functional response bioassay was performed with two Trichogramma lineages and different egg densities of the host.

Study Design: Adopting a totally randomized experimental design, 10 replications were finished each species.

Place and Duration of Study: The bioassay was conducted at the Entomology Laboratory of the Universidade Federal do Espírito Santo (CCAE-UFES) in Alegre, ES, Brazil, within the year 2017. [5]

Reference

[1] Vet, L.E., Lewis, W.J. and Carde, R.T., 1995. Parasitoid foraging and learning. In Chemical ecology of insects 2 (pp. 65-101). Springer, Boston, MA. (Web Link)

[2] King, B.H., 1987. Offspring sex ratios in parasitoid wasps. The quarterly review of biology, 62(4), (Web Link)

[3] Strand, M.R. and Pech, L.L., 1995. Immunological basis for compatibility in parasitoid-host relationships. Annual review of entomology, 40(1), (Web Link)

[4] Host density and parasitoid presence interact and shape the outcome of a tritrophic interaction on seeds of wild lima bean
Maximilien A. C. Cuny, Juan Traine, Carlos Bustos-Segura & Betty Benrey
Scientific Reports volume 9, (Web Link)

[5] Pereira Paes, J., Souza Lima, V., de Carvalho, J. and pratissoli, D. (2018) “Functional Response of Two Egg Parasitoids of Trichogramma (Hymenoptera: Trichogrammatidae) Genre on Duponchelia fovealis Zeller (Lepidoptera: Crambidae) Eggs”, Journal of Experimental Agriculture International, 20(6), (Web Link)

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