Sperm Use Entry into the Egg and Fertilization 61 Sperm

Compared to mammals where about 10 million sperm are ejaculated to fertilize one or a few eggs, insects show remarkable economy in this regard. For example, the queen bee spermatheca contains about 5 million sperm, yet she produces on average at least 200,000 fertilized eggs during her 4-year life span. In other words, an average of about 25 sperm per egg are released from the spermatheca. This suggests that a very precise control mechanism exists for sperm release though almost nothing is known about the process.

Females of some species are essentially monogamous; that is, they mate once, then become unreceptive or unattractive to males as a result of chemicals from the successful male's seminal fluid (Section 4.3.1). In such females, therefore, the question of sperm competition (which male's sperm will be used to fertilize the eggs) does not arise. Most female insects, however, mate several to many times (though they may become unreceptive for some time after each mating), receiving new sperm (and sometimes nutrients) on each occasion. In these species sperm competition will occur, especially if sperm from the various donors mix in the storage organs. It is clear, however, that sperm use in multiply mated insects is non-random; that is, strategies have evolved to ensure that some sperm take precedence over others. These strategies may be either male- or female-driven.

From the male's perspective the simplest strategy is to be the most recent mate, as his ejaculate will thus tend to be closest to the opening of the spermatheca; indeed, in most insects the "last in, first out" method of sperm precedence occurs. However, strengthening of this positional advantage may be achieved by various means, including sperm stratification

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

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