FITNESS PERFORMANCE OF IMMATURES UNDER SUPERPARASITISM AND SUPERPARASITISM STRATEGY IN AN INFANTICIDAL SEMI-SOLITARY PARASITOID (HYMENOPTERA: DRYINIDAE): EFFECTS OF SIZE OF OVIPOSITING FEMALES

Herlin, Weri (2019) FITNESS PERFORMANCE OF IMMATURES UNDER SUPERPARASITISM AND SUPERPARASITISM STRATEGY IN AN INFANTICIDAL SEMI-SOLITARY PARASITOID (HYMENOPTERA: DRYINIDAE): EFFECTS OF SIZE OF OVIPOSITING FEMALES. Doctoral thesis, Mie University.

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Official URL: https://doi.org/10.1007/s00114-019-1648-3

Abstract

Echthrodelphax fairchildii Perkin (Hymenoptera: Dryinidae) is an infanticidal koinobiont semi-solitary ectoparasitoid of planthoppers in the paddy fields. The female lays an egg under the forewing bud of the host for one parasitism bout, but two adults often emerge under superparasitism with short first-to-second oviposition intervals. The female often moves the abdominal tip to the non-oviposition side to probe for infanticide before laying an egg. Parasitized hosts continue to feed on host plants, but they do not molt. Here, I explored the fitness performance of immature parasitoids under superparasitism and superparasitism strategy using the fourth-instar host, lower in quality than the fifth-instar host. I examined superparasitism with oviposition intervals of 0, 1, and 24h. I also determined the fitness performance of immature parasitoids under single parasitism for comparison. 1)Survival rates and adult body sizes of both the male and female offspring increased with increasing body sizes of their mother under single parasitism, and consequently small females failed in producing female adults. 2)Survival rates of the first and second offspring was revealed under self and conspecific superparasitism. Two-adult emergence occurred at 0- and 1-h oviposition intervals. The first egg was assumed to be killed by the second female under same-side superparasitism (two eggs are laid on the same side) based on the previous study using fifth-instar hosts. This assumption was proved true by comparing the oviposition-to-larval-sac-appearance period of the offspring under same-side superparasitism with an oviposition period of 24 h with that of the offspring under single parasitism. The survival rate of the second offspring under same-side self-superparasitism was lower than under different-side self-superparasitism. It was true for conspecific superparasitism when second females were small, and the probing did not occur. The probing did not ensure higher survival of the second offspring except for under self-superparasitism with a 24-h oviposition interval. The effect of oviposition intervals was found only under different-side superparasitism without probing: the survival rate of the second offspring decreased with increasing oviposition intervals. Under different-side superparasitism without probing, the survival rates of the first and second offspring were higher under conspecific than self-superparasitism mainly when the first and/or second females were small. Meanwhile, self/conspecific difference was not found under different-side superparasitism with probing or same-side superparasitism 3)The effect of mother body size was found under superparasitism also: larger mothers ensured higher survival of their offspring. The size of ovipositing females did not influence the survival of non-relative offspring. An exception was different-side conspecific superparasitism without probing, under which the first female’s size had positive and negative effects on the survival rates of her offspring and the second offspring, respectively, while the second female’s size had no effect on the survival of her offspring or the first offspring. When the probing occurred, the negative effect of the first female’s size on the survival of the second offspring was not found, and the second female’s size had a positive effect on the survival of her offspring. These suggest that the offspring, not the ovipositing females, release host-physiology regulating agents, and that offspring from larger mothers release a larger amount and/or more effective type of such agents than offspring from small mothers. Large females always or almost always performed superparasitism while middle-sized and small females more likely did it with increasing oviposition intervals. Then, small females distinguished between self- and conspecifically parasitized hosts when the oviposition interval was 0, while middle-sized and large females did not. When parasitoids was large and middle-sized, the probing rate increased with increasing oviposition intervals with no difference between self- and conspecific superparasitism. Meanwhile, small females hardly perform probing irrespectively of the oviposition interval. Most of the eggs laid under superparasitism were male, but as ovipositing females were larger, the proportion of female eggs increased. Ovipositing females prefer different-side superparasitism to same-side superparasitism. These patterns of behavior were considered to be adaptive in light of the fitness gains from superparasitism, self/conspecific distinguishing ability, difference in egg load, longevity, and relative cost for the focal behavior between different-sized females, and the fact that the females were kept with very little chance to encounter high-quality hosts.

Item Type: Thesis (Doctoral)
Subjects: S Agriculture > S Agriculture (General) > S589.7 Agricultural ecology (General)
Divisions: 05-Faculty of Agriculture > 54001-Agricultural Science (S3)
Depositing User: Mrs Weri Herlin
Date Deposited: 13 Sep 2022 03:01
Last Modified: 13 Sep 2022 03:33
URI: http://repository.unsri.ac.id/id/eprint/78640

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