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The mutualistic association between ants and hemipterans is often facultative and can be affected by the availability of other food sources. In the present study we tested whether the tending behavior of the big-headed ant, Pheidole megacephala (Fabricius), had a negative impact on the pink pineapple mealybug, Dysmicoccus brevipes (Cockerell), when alternative food sources: (1) sugar solution, (2) purified water + mealworms and (3) sugar solution + mealworms versus with purified water (control) were provided to the ant colonies. We found that the frequency of ant tending on D. brevipes decreased when ants were provided with alternative food sources. However, we did not see any aggressive behaviors and predation of ants on D. brevipes. Also, the survival of D. brevipes was not different among food condition treatments. These results suggest that the decreased tending frequency of ants can lead to the decline in ant protection service to mealybugs. [ABSTRACT FROM AUTHOR]

The males of many insect species transfer a spermatophore, i.e., a proteinaceous capsule containing sperm, to females during copulation, and this may also function as a nuptial gift. If production of the spermatophore is costly and variations in the quality of females are large, males may strategically allocate their investment based on the quality of the mate to maximize their own reproductive success. We examined the size and protein content of spermatophores transferred to females of different ages and body sizes, and also to water-deprived and water-replete females in the moth Ostrinia scapulalis (Walker). Males transferred a spermatophore of a smaller size or with less protein to older females, smaller females, and water-deprived females. These results indicated that O. scapulalis males manipulated their reproductive investment based on the conditions of the mate. We also demonstrated that older males varied their resource allocation to a greater extent in response to female conditions than younger males. Thus, resource allocation by the males of this species is modulated by both female conditions and the age of the males. [ABSTRACT FROM AUTHOR]