Shun'ichi Makino

Reproductive and subsocial behaviour in the ovoviviparous leaf beetle Gonioctena sibirica (Coleoptera: Chrysomelidae)

Abstract. 1 In the spring, females of the leaf beetle Gonioctena sibirica deposited larvae on the ventral surface of growing young leaves situated on the apical position of shoots of the willow Salix bakko. 2 The parent females remained with the larvae usually on the underside of the basal part of leaves, facing toward the base of shoots. When other arthropods approached, the females temporarily moved towards these intruders, showing aggressive behaviour such as swinging the body or stamping the legs. Many females remained with their larvae until the larvae grew into the final (fourth) instar. No female produced an additional brood in the field. 3 Broods from which parent females were experimentally removed suffered higher mortality than those in which females were left intact. Arthropods such as spiders and ants were observed preying on the larvae. In contrast, the survivorship of broods from which females were removed and intruders were excluded with a sticky substance applied to the base of twigs was not different from that of control broods. These results demonstrate that the main mortality factor of offspring is pedestrian arthropod predators and females physically repel the predators. 4 Potentially alternative reproductive strategies, such as producing a large number of offspring by iteroparity and/or larger brood(s) with less or no care, seem to be inhibited in G.sibirica by larval dependence on growing young leaves which are temporally limited and by ovoviviparity which may have limited brood size.

Comparison of intraspecific nest usurpation between two haplometrotic paper wasp species (Hymenoptera: Vespidae:Polistes)

Intraspecific nest usurpation by foundresses was studied in 2 haplometrotic (solitary founding) species of different subgenera,Polistes (P.) riparius andP. (Polistella) snelleni, in areas where they cohabited. The overall probability for a nest to be usurped by a foreign foundress during the season was about twice as large inP. snelleni as inP. riparius. In both, however, probability of usurpation was largest on late pre-emergence nests, or in late June and early July. InP. riparius, all the usurpers of known origins were those foundresses that had lost their pre-emergence nests to destruction probably by some vertebrates; inP. snelleni, some usurpers had the same history as above, while the others had lost many of all larvae to predation by unknown agents before worker emergence. Usurpers of both species destroyed eggs and younger larvae to much greater extents than older larvae or pupae, and they produced fewer numbers of reproductives in comparison with non-usurping foundresses. We concluded that usurpation behavior has been maintained despite its relatively low productivity because renesting would lead to even lower or no reproductive production.

Losses of workers and reproductives in colonies of the paper waspPolistes riparius (Hymenoptera: Vespidae) due to the parasitic waspLatibulus sp.

1. Losses in workers and reproductives due to the ichneumonid parasitoidLatibulus sp. were determined in a haplometrotic, temperate paper wasp,Polistes riparius, during a 5-year study. 2. Fifty-four to 79% of pre-emergence nests were parasitized on worker brood, resulting in a worker loss of 25–31% on average. Worker brood reared in outer cells were much more often parasitized than those in central ones, possibly because outer cells are more accessible to the parasitoid. Infestation of worker brood was not random but aggregated among nests. 3. Seventy-eight to 100% of nests were parasitized on reproductive brood, and lost 10–34% of reproductives. 4. The number of emerged workers positively correlated with that of reproductives produced and that of cells made during the season. This suggests that worker loss reduces reproductive output of colonies. Hence, the parasitoid can reduce colonial reproductive output not only by killing reproductive brood but by reducing worker force. Losses in workers and reproductives due to the ichneumonid parasitoidLatibulus sp. were determined in a haplometrotic, temperate paper wasp,Polistes riparius, during a 5-year study. Fifty-four to 79% of pre-emergence nests were parasitized on worker brood, resulting in a worker loss of 25–31% on average. Worker brood reared in outer cells were much more often parasitized than those in central ones, possibly because outer cells are more accessible to the parasitoid. Infestation of worker brood was not random but aggregated among nests. Seventy-eight to 100% of nests were parasitized on reproductive brood, and lost 10–34% of reproductives. The number of emerged workers positively correlated with that of reproductives produced and that of cells made during the season. This suggests that worker loss reduces reproductive output of colonies. Hence, the parasitoid can reduce colonial reproductive output not only by killing reproductive brood but by reducing worker force.

Elicitation of Both Anti HIV-1 Env Humoral and Cellular Immunities by Replicating Vaccinia Prime Sendai Virus Boost Regimen and Boosting by CD40Lm

For protection from HIV-1 infection, a vaccine should elicit both humoral and cell-mediated immune responses. A novel vaccine regimen and adjuvant that induce high levels of HIV-1 Env-specific T cell and antibody (Ab) responses was developed in this study. The prime-boost regimen that used combinations of replication-competent vaccinia LC16m8Δ (m8Δ) and Sendai virus (SeV) vectors expressing HIV-1 Env efficiently produced both Env-specific CD8+ T cells and anti-Env antibodies, including neutralizing antibodies (nAbs). These results sharply contrast with vaccine regimens that prime with an Env expressing plasmid and boost with the m8Δ or SeV vector that mainly elicited cellular immunities. Moreover, co-priming with combinations of m8Δs expressing Env or a membrane-bound human CD40 ligand mutant (CD40Lm) enhanced Env-specific CD8+ T cell production, but not anti-Env antibody production. In contrast, priming with an m8Δ that coexpresses CD40Lm and Env elicited more anti-Env Abs with higher avidity, but did not promote T cell responses. These results suggest that the m8Δ prime/SeV boost regimen in conjunction with CD40Lm expression could be used as an immunization platform for driving both potent cellular and humoral immunities against pathogens such as HIV-1.

Sexual differences in larval feeding behavior in a paper wasp,Polistes jadwigae (Hymenoptera, Vespidae)

In some eusocial wasps of Polistes and Mischocyttarus, males have been reported to provide larvae with prey pellets that they receive from other wasps (West Eberhard 1969; Yamane 1969; Jeanne 1972; Hunt & Noonan 1979; Makino 1983; Cameron 1985). If they distribute prey to larvae as workers do, we should not think that males are irrelevant to the production of new adults. However, it is doubtful whether this behavior is really a form of larval care. One reason is that they masticate prey pellets longer than workers do before giving them to tarvae (Jeanne 1972; Hunt and Noonan 1979; Cameron 1985). This suggests that males extract a large amount of liquid from prey pellets, thus selfishly taking nourishment, and only provide larvae with remnants. Difference in mastication time between females and males, however, has not been tested statistically. I report sexual differences in prey mastication time and in prey handling in Polistes jadwigae.