Submitted to: International Congress of Invertebrate Reproduction
Publication Type: Abstract Only
Publication Acceptance Date: 5/17/2001
Publication Date: N/A
Technical Abstract: Perillus bioculatus are predators of the Colorado potato beetle. Mass rearing of these predators has been hampered by the absence of inexpensive artificial diets. Analysis of yolk protein precursors, vitellogenins (Vgs), in the hemolymph might provide a means of evaluating artificial diets. Vitellogenic oocytes have two native vitellins, Vt1 and Vt2, with molecular weights of 577 and 350 kDa, respectively. These Vts are the result of the incorporation of Vgs into the oocyte to form yolk. Vt2 was purified with preparative electrophoresis and polyclonal antibodies to Vt2 were built in rabbits. An ELISA was developed with a sensitivity range of 3 to 100 ng. Vitellogenesis starts in ovaries with a score of 12 at 2.4 days after emergence. The first cycle of egg development is completed in ovaries with a score of 112 at 7.7 days. During this time the ovaries of a single female incorporate 1835 uG of Vg to form Vt indicating that the female is making Vg at the rate of 14.4 uG/h. Vg levels start to increase in females 2.5 days after emergence and reached a peak of 17.8 uG/uL by 5.5 days. After this time Vg levels fluctuated between 9.7 and 19.9 uG/uL. When these insects were maintained on a liver-based artificial diet, vitellogenin levels were significantly lower than the controls at all sample times to the time the experiment was discontinued at 11.5 days. Vitellogenin levels varied from 0.026 uG/uL to 6.703 uG/uL in insects given the artificial diet. An inadequate diet may result in the absence of essential materials needed for vitellogenin synthesis such as amino acids, lipids or carbohydrates. Using the ELISA to measure Vg levels would allow one to evaluate diet effectiveness in females held on test diets for only 3 days.