Why Oviposit There? Fitness Consequences of a Gall Midge Choosing the Plant's Youngest Leaf

Abstract

For animals that lay eggs, a longstanding question is, why do females choose particular oviposition sites? For insects that lay eggs on plants there are three hypotheses: maximizing suitable habitat for juveniles, maximizing female lifespan, and maximizing egg survival. We investigated the function of the oviposition-site choice behavior of a gall midge, the Hessian fly, Mayetiola destructor (Say). In spite of living less than a day and having hundreds of eggs, the ovipositing female is choosy about the placement of eggs. Choosiness makes sense. The tiny gall-making neonate larva has limited movement and strict requirements for colonization. We examined whether offspring benefit from the Hessian fly female's preference for the plant's youngest leaf. To do this we restricted the female's access to the first, second, or third leaf of a seedling (wheat Triticum aestivum L.) plant. Being placed on older leaves did not impact egg survival or larval survival during migration to attack sites at the base of the plant, but did have negative impacts on egg-to-adult survival (reduced by 48%) and reproductive potential (reduced by 30-45%). These negative impacts appear to come from larvae having to search harder to find the limited number of reactive plant cells that can be reprogrammed to form the gall nutritive tissue. We propose that the ability of larvae to find these reactive cells in spite of being placed on an older leaf is important because it creates leeway for female behavior to evolve in the face of other selection pressures, e.g., attack by egg parasitoids.

Interspecific competition drives gall‐inducing insect species distribution on leaves of Matayba guianensis Aubl. (Sapindaceae)

“…Some studies have shown that spatial distribution of galls within an individual plant and even within the same leaves is associated with the nutritional quality variation of the plant tissues (Egan & Ott, 2007;Cornelissen et al, 2008;Matsukura et al, 2012). Thus, it is possible to expect that the position where galls are induced within the host plant are directly related to gall-inducing insects' performance (Aoyama et al, 2012;Ganehiarachchi et al, 2013). In our study, the spatial distribution of both B. mataybae and L. mataybae galls on leaflets of M. guianensis showed that these gall-inducing insect species differentially select specific oviposition sites on leaflets with different size (i.e., young and nutritious tissues) to develop their galls.…”

Home for Marine Species: Seagrass Leaves as Vital Spawning Grounds and Food Source

“…The translucent egg capsule of S. bryanae has also been found on the leaf basal section of H. hawaiiana (Unabia, 2011). A large number of species have a specific oviposition behavior as they select a narrow range of plant species as well as particular parts of a plant (Ganehiarachchi et al, 2013). This could be explained by the hypothesis of maximizing embryo survival.…”

Pivoting from Arabidopsis to wheat to understand how agricultural plants integrate responses to biotic stress

“…The Hessian fly's inability to evolve these mechanisms makes more sense when one realizes that, in order to have optimal egg-laying behaviour regarding H genes, the female would need to know which H gene the plant has, as well as the virulence of her own offspring relative to that particular H gene (Harris et al, 2001). The female typically places eggs on the adaxial surface of the blade of the seedling's youngest leaf, a behaviour that presumably helps neonate larvae find the 'reactive sites' that are amenable to formation of the nutritive tissue (Ganehiarachchi et al, 2013). The larva emerges from the egg 3 d later.…”