Jeffrey Y. Honda

Interactions between host attributes and wasp size : a laboratory evaluation of Trichogramma platneri as an augmentative biological control agent for two avocado pests

We compared egg parasitization of two sporadic pests of avocado, Persea americana Miller, by Trichogramma platneri Nagarkatti reared on Sitotroga cerealella (Oliver) (=smaller parasitoids) with those reared on Trichoplusia ni (Hübner) (= larger parasitoids) in the laboratory. Large T. platneri females invested less time than smaller parasitoids in obtaining offspring from eggs of either Amorbia cuneana Walsingham or Sabulodes aegrotata (Gueneé). Furthermore, large T. platneri invested substantially more time (ca. 3‐fold) in obtaining offspring from S. aegrotata than A. cuneana eggs. These investment times positively correlated with percentage egg‐load retained by a female after it had ceased exploiting a host species. This occurred even though the offspring produced by a parasitoid from either host species manifested the same size and fecundity (= quality). Host species utilization in the laboratory mirrored that observed in the avocado groves of southern California following augmentative release of commercially produced T. platneri (Oatman & Platner, 1985). Explanations for these differences in host utilization are discussed along with their implications for augmentative biological control.

Olfactory response of Anagrus, nigriventrls (HYM.: Mymaridae): Effects of host plant chemical cues mediated by rearing and oviposition experience

The egg parasitoid Anagrus nigriventris Girault is an important natural enemy of the beet leafhopper, Circulifer tenellus (Baker) which has a broad host range that includes cultivated sugar beets and the weed, Russian thistle. When parasitoids were reared on leafhopper eggs deposited in sugar beets, females were attracted to sugar beet volatiles and preferred them over a blank control and over Russian thistle volatiles in Y- tube olfactometer tests. No preference was detected for either plant by female wasps that were reared on Russian thistle. Wasps reared on Russian thistle and allowed an oviposition experience on sugar beet showed a strong attraction to sugar beet volatiles; however, wasps reared on sugar beets and allowed oviposition experience on Russian thistle demonstrated no preference between the two plants. The implications of parasitoid response towards plant volatiles and their importance in biological control are discussed.RésuméLe parasitoÏde oophageAnagrus nigriventris est un ennemi naturel important de la cicadelleCirculifer tenellus qui a une large gamme de plantes hÔtes comprenant aussi bien la betterave sucrière que des plantes sauvages commeSalsola tragus L. Lorsque les parasitoÏdes sont élevés sur des oeufs de cicadelles pondus dans des betteraves sucrières, les femelles sont attirées par les composés volatiles de la betterave et les préfèrent au témoin neutre ou aux composés deSalsola lors des tests en olfactomètre (tube en Y). On ne note aucune préférence pour l’une ou l’autre plante dans le cas de femelles élévées surS. tragus. Ces dernières qui ont une expérience de ponte sur betterave montrent par la suite une forte attraction pour les composés volatiles deS. tragus; cependant les parasitoÏdes élevés sur betterave et qui font l’expérience de ponte surS. tragus ne montrent aucune préférence entre les deux plantes. Les implications des réponses de ces parasitoÏdes vis-à-vis des composés volatiles issus de plantes et leur importance dans la lutte biologique sont discutées.

Laboratory bioassay and greenhouse evaluation of Trichogramma cordubensis strains from Portugal

A simple, inexpensive chamber was developed and tested as an evaluative tool to monitor Trichogramma cordubensis dispersal in the laboratory. The chamber consisted of a continuous, winding channel which was cut into an aluminum block. Wasps were released at one end of the channel and allowed to walk in the channel for 21 h and to parasitize Mamestra brassicae eggs placed 3.4 m from the point of wasp introduction. Comparisons between two T. cordubensis populations demonstrated that one population (TCM) dispersed more in the chamber and located host eggs more successfully than the other population (TCD). Subsequent greenhouse releases confirmed that the TCM population dispersed more readily and had significantly higher parasitism rates on sentinel Ephestia kuehniella eggs on tomato plants. The potential utilization of this chamber as a tool to evaluate quality of Trichogramma populations, mainly dispersal activity, is discussed.

Sodium polyacrylamide polyacrylate, a gelling agent in diets for cabbage looper, omnivorous looper and western avocado leafroller

Ingredient substitutions for agar or carrageenan in artificial diets for lepidopterous larvae were evaluated. A sodium polyacrylamide polyacrylate gelling agent, Water‐Lock G‐400, was compared with agar for solidifying diets of the cabbage looper, Trichoplusia ni (Hübner), omnivorous looper, Sabulodes aegrotata (Gueneé), and the western avocado leafroller, Amorbia cuneana Walsingham. Water‐Lock G‐400 is considerably less expensive than agar or carrageenan, it does not require heating to gel, and it is made from a dependable supply of agricultural starch.